Magpie

Built for breakthroughs in geoscience, defense, and research.

Magpie is a compact, field-ready magnetometer system built around QuSpin’s QTFM Gen-2 sensor. It integrates a high-sensitivity magnetometer, GNSS, an IMU, onboard logging to an internal microSD card, and wireless connectivity into a single lightweight package.

Magpie can be operated using the Windows application over bluetooth for live plots, configuration, and data recording, or via a web browser over Wi-Fi through the MiniACB page for basic control and file access. For field use, the Magpie Android app provides a fast interface to send commands, view status, monitor real-time plots, and manage recordings from a mobile device.

Magpie also supports an optional vector add-on for triaxial (Bx, By, Bz) magnetic field measurements.

This manual covers setup, safe handling, connections, software operation, data stream format, hardware operation, technical reference and troubleshooting.

Contents may vary by configuration. Verify your shipment against the packing list. Many items can also be bought off the shelf; where possible, a vendor link is provided.

2.1  Standard Items (Typical)

• Magpie Unit — the white plastic outer shell (the standard, default configuration) plus the internal sled and strain-relief hardware that the QTFM Gen-2 sensor is pre-mounted to. The shell, sled, and mounting hardware ship as one assembled unit. The white plastic shell is recommended over carbon-fiber for most applications because it offers better thermal regulation, stronger Bluetooth and Wi-Fi performance, and is transparent to GPS, allowing use of the internal GPS antenna without any additional accessory.
• 11.1 V (3S), 1800 mAh Li-Po battery pack (if ordered) — Battery weight 96 g. Approximately 4-hour operation time from full charge. Note: Any 11.1 V LiPo is compatible; the Magpie input range is +9.0–13.9 VDC. (Amazon)
• Internal passive GPS flex antenna (SRFG017-100) — Pre-installed inside every Magpie. The standard plastic shell is GPS-transparent — an external antenna is only required for carbon-fiber shells or limited sky view. (DigiKey)
• microSD card (32 GB, + SD adapter) — pre-installed for onboard logging and removable for offload (see Setup). Practically any 32 GB card works; a high-endurance card is recommended for sustained recording.
• 2-pin power cable terminated with the Magpie’s Julet connector on one end and a battery-pack connector on the other, plus a pair of spare male/female 2-pin connectors for repairs or rebuilds. (AliExpress)
• 2-pin + 6-pin breakout board (Julet M6 waterproof connectors) — The 2-pin cable carries battery power; the 6-pin cable breaks out the sensor serial UART (Rx/Tx), ground, and Sync_Input/Sync_Output. See Pinout in hardware.
  
• Spare male/female 6-pin Julet M6 connector pair (for repair or rebuild of the breakout cable). (AliExpress)

The following ship once per order, not per Magpie:

• 11.1 V (3S) 1500 mA Li-Po battery charger (if battery pack is ordered) — Charges the included Li-Po pack from USB through its XH-4P balance connector. (Amazon)
• Digital LiPo battery capacity / cell-balance tester (CellMeter-style, if battery pack is ordered) — Plugs into the battery’s balance lead. Used to confirm individual cell voltages and remaining capacity before each deployment. (Amazon)
• Standard QuSpin Comms board — Used only to update the QTFM Gen-2 sensor firmware via the flex-cable connector on the side of the Magpie’s MiniACB board; it is not required for normal Magpie operation.
• USB Wi-Fi dongle (TP-Link TL-WN725N, N150 nano) — Plug the dongle into your PC to associate with the Magpie’s Wi-Fi access point for the MiniACB browser interface, while leaving your PC’s built-in Wi-Fi free to stay on your normal network. (Amazon)

2.2  Optional Items

• Vector add-on (triaxial Bx/By/Bz Magpie variant). The vector coils wrap around the standard single-axis sensor head. The vector-electronics board stacks directly on top of the Magpie electronics as an addition, not a replacement.
• Carbon-fiber shell upgrade — Replaces the standard white plastic shell. Because carbon fiber attenuates GPS and degrades Wi-Fi/Bluetooth range, every carbon-fiber shell upgrade ships bundled with an external active GPS antenna (AN-GPS-A001-MMCX); the internal flex antenna is bypassed via the on-board jumper described in the GPS Antenna Guide. Choose this option only if you specifically need carbon fiber for mechanical, environmental, or aesthetic reasons; the default plastic shell is the recommended choice for most applications. External antenna (AN-GPS-A001-MMCX): DigiKey.

3.1  Quick Start (Bluetooth)

This quick sequence covers first power-up and a basic recording. For a video demonstration, see the online guide →

1. Connect the 11.1 V battery pack (see Everyday Operation).
2. Wait for the Sensor LED to turn solid blue, indicating normal operation (see LED Codes).
3. Download and install the QTFM2 Windows application, then open it (see Software Installation).
4. Connect your computer to the Magpie over Bluetooth for control and live data (see Connecting to Bluetooth).
5. In the app, click “Connect” and select the Magpie by its serial number (about 10 seconds).
6. Verify live data in the user interface.
7. Click “Record” to set up a logging file, then “Start Recording” and let it run for a short test capture.

For Wi-Fi, see Connecting to Wi-Fi. A GPS lock can take several minutes; for the fastest lock, give the Magpie a clear view of the sky.

3.2  Initial Checks & Pre-Deployment Checklist

Every Magpie is tested before it ships, but a quick check before each deployment catches problems before they cost you data. To connect and start logging, see the online guide and quick-start video; the checks below confirm the unit is healthy and ready.

On Initial Power-Up

• LEDs indicate full operation. The Sensor LED turns solid blue for valid data; the Logger LED must not be red. See LED Codes.
• Autostart completes. In the QTFM2 software, watch for #Laser Lock Engaged → #Autostart Complete → #Cell Locked, in that order (see Status Message Reference).
  If autostart stalls or the laser won’t lock, run Sensor Reoptimization.
• No fault or warning messages. The terminal should be clear of error and stop-condition messages after boot. See Status Message Reference.

In the Field

• Profile and settings are loaded. Confirm the sensor profile and output rate you intend for this survey (scalar vs vector, data rate). See the Sensor Profile Configuration guide.
• GPS has locked. Give the Magpie a clear view of the sky; a 3D fix can take several minutes, GNSSFIX appears in the data stream. See GPS Antenna Guide.
• SD card is ready. Confirm #SD card initialized successfully at boot and that there is room for the planned recording ([get_sd_card_info]). See SD Card Management.
• If applicable: synchronization is verified (multi-unit). Verify the sync on each sensor before relying on cross-unit timing. See Time Synchronization.

3.3  Software Installation

Magpie supports three user interfaces: a Windows PC application, a browser-based interface hosted on the device (MiniACB over Wi-Fi), and an android app available on google play. The QTFM2 UI Windows application provides live magnetic plots, a serial terminal for configuration, and recording and post-processing tools, while the Magpie Android app provides a fast interface with similar functionality from a mobile device. The MiniACB interface is a lightweight web page for basic status, a serial terminal, simple controls, and access to files stored on the internal microSD card.

Install the Windows Application

1. Download the latest QTFM Gen-2 User Interface from QuSpin.
2. Launch the installer and complete installation.
3. When Windows prompts, allow the application through Windows Firewall.

3.4  Connecting to Bluetooth

Magpie supports Bluetooth serial (SPP) for use with the Windows application.

Pair Magpie with Windows

1. Open Windows Settings → Bluetooth & devices → Add device → Bluetooth.
2. Select the device that matches the Magpie serial number and complete pairing.

Changed the serial number? A serial-number change alters the unit’s Bluetooth identity, so Windows sees it as a new device. See Troubleshooting and FAQ for re-pairing steps.

Improve Streaming Performance (Recommended)

1. Open Device Manager → Ports (COM & LPT) → select the Magpie outgoing COM port → Properties → Port Settings → Advanced.
2. Set “Receive Buffer” to the lowest setting to reduce apparent lag in live plots.
3. In the Windows application, select the Magpie outgoing COM port and confirm you see live data.

3.5  Connecting to Wi-Fi

Magpie provides a Wi-Fi access point for the MiniACB browser interface.

1. Open your device Wi-Fi settings and select the Magpie access point (SSID is typically the Magpie serial number).
2. When prompted, enter the default password: 12345678.
3. After connecting, open a web browser and navigate to http://miniacb/.

Note Your computer may show “No internet” while connected to Magpie Wi-Fi; this is expected. If your network does not resolve http://miniacb/, use the fallback IP address provided with your shipment.

Magpie logs data to the internal microSD card. You can start/stop logging and retrieve files using either the Windows/Android application (Bluetooth) or the MiniACB browser page (Wi-Fi), depending on your workflow.

4.1  Good Logging Practice

• Wait for valid magnetic data before starting a critical recording.
• Stop logging using the software controls before disconnecting power.
• If the Logger LED indicates an SD-card or power issue, stop the run and correct the issue before continuing.
• After each session, confirm your files are present and copy them to your computer for backup.

Magpie supports four sync modes depending on your deployment. Section 5.1 helps you pick one; subsequent sections cover each in detail. For step-by-step setup instructions and command sequences, see the published Syncing Your Gen-2 QTFM Sensors guide.

5.1  Choosing a Sync Mode

5.2  Wired Master / Slave

Two or more Magpies share timing over a physical sync cable with no external timebase or GPS required — the array agrees on a common cycle even indoors. Run a wire from the master’s Sync_Output (Green) to each slave’s Sync_Input (Orange) on the 6-pin breakout cable, and tie all grounds together. For the wiring pinout see the 6-Pin Breakout Cable chapter; for the command sequence see the Magpie Command Guide and the Syncing Your Gen-2 QTFM Sensors guide.

5.3  Wireless GPS Sync (Magpie → Sensor)

Each Magpie contains a single QTFM Gen-2 sensor, but multiple Magpies are often deployed together to form gradiometers, multi-axis arrays, or distributed surveys. Starting with the V1_43+ sensor firmware and the matching V10+ Magpie firmware, every Magpie can wirelessly time-align its sensor to absolute UTC using its on-board GPS — no shared sync cable required. Sensors in a wireless-synced array automatically lock onto the same UTC time base shortly after each Magpie’s GPS module acquires a fix, and stay locked for the duration of the log. Post-processing alignment then comes down to matching the UTC timestamps embedded in every line.

How It Works

The Magpie’s GPS module captures both an absolute UTC time and a hardware 1 Hz Pulse-Per-Second (PPS) signal. Once per second, the Magpie packs the current UTC time into an 11-byte frame (sync bytes 0xAA 0x55, an 8-byte UTC millisecond counter, and a CRC-8) and forwards it to the QTFM sensor over UART, timed off the PPS edge so the frame arrives with sub-microsecond jitter. The sensor (in GPS Sync mode, FPGA addr 30 = 3) realigns its internal cycle counter to that UTC reference, so every magnetometer sample is timestamped against absolute UTC. When the same reference is shared across multiple Magpies, all of their sensors converge to the same time base and the samples line up to better than a millisecond on every PPS edge.

Quick Start

The Magpie’s GPS receiver is off by default to save power. To bring up turnkey wireless sync, send two commands to the Magpie once (they persist across reboots): [GPS on] then [gps_sync_auto on]. In auto mode the Magpie waits for the GPS fix, polls the sensor until it is cell-locked, sends the sensor its sync commands, and begins forwarding UTC — you never send any commands to the sensor. The sequence is:

1. Position each Magpie under open sky and power it on.
2. Send [GPS on], then [gps_sync_auto on], over the Magpie’s Wi-Fi terminal, Bluetooth terminal, or USB console. Monitor progress with [gps_sync status].
3. Wait for the Logger LED to reach white (both GNSS and magnetic data present) and the Sensor LED to turn solid white — wireless sync is now active.
4. Start logging. All UTC timestamps embedded in the data stream are now common across every Magpie in the array, so post-processing alignment is a direct join on the UTC time base.

For step-by-step setup, the underlying sensor commands (cmd 113 to enter GPS Sync mode, 206 to enable, 209 to arm a one-shot lock, 230 for periodic re-arm on long runs, 231/232/233 to realign or disarm, 234 for the PPS status debug, 235 to toggle the LED between solid white and the troubleshooting rainbow), the External-PPS alternative, and a verification walkthrough, see the Syncing Your Gen-2 QTFM Sensors guide.

5.4  PTP / IEEE 1588

When the deployment network carries an IEEE 1588 grandmaster, the Magpie can discipline its clock to PTP over Ethernet. This path requires the W5500 Ethernet breakout board (see Ethernet Operation). Enable live with [ptp on] or at boot with [ptp boot on], and discipline the offset estimator to the GPS PPS edge with [ptp pps on] for sub-microsecond stability. See the PTP Time Synchronization commands in the Magpie Command Guide.

5.5  External PPS

For GPS-denied environments or arrays that share an external GPS-locked 1 PPS source, connect the 0–3.3 V PPS line to every sensor’s Sync_Input (Orange) on the 6-pin breakout cable and tie all the grounds together. No UTC is required — every sensor slaves its 1 Hz cycle to the shared hardware pulse. This mode requires the sensor’s FPGA bitstream at v5.05 or later. See the Syncing Your Gen-2 QTFM Sensors guide for the wired External-PPS recipe.

5.6  Verifying Sync

Two quick visual checks confirm sync is live. (1) The Sensor LED is solid white whenever the sensor is GPS-wireless synced and the current measurement is good — this is the default. (2) For a per-second cross-sensor sanity check, send sensor command 235 to enable the troubleshooting rainbow: every Magpie in the array steps through Yellow → Green → Cyan → Blue → Purple in lockstep, one color per UTC second. The rainbow radiates a small 1 Hz magnetic signature, so revert to solid white (reboot the sensor, or toggle 235 again) before recording critical data. For a numerical confirmation, sensor command 234 enables a once-per-second debug line (#PPS dbg… edges= advancing, locked=1) that proves the sensor is actually receiving and edge-locking to the PPS reference.

Magpie outputs an ASCII serial stream and logs it to a text file, where each line is one message (magnetometer samples, optional IMU packets, and GNSS fixes). Because these messages arrive as mixed line types, many post-processing tools work best if the data are converted into a clean, tabular CSV with a consistent time base. This chapter describes the line format and QLog_Processor, the QuSpin utility that turns a raw log into analysis-ready CSVs.

6.1  Data Structure

The Magpie logs every message from the QTFM Gen-2 sensor to an ASCII text file and augments the sensor’s native stream with two things: a high-resolution microsecond timestamp prepended to every line, and interleaved GPS position/time lines. The underlying sensor data format is identical to what the QTFM Gen-2 outputs natively — for the full sensor-level specification, see the QTFM Gen-2 Serial Communication and Data Format guide.

The Magpie Data Stream

Every line the Magpie outputs is prepended with a microsecond timestamp. After that timestamp, the first character identifies one of three line types:

Microsecond Timestamp

The Magpie prepends a microsecond timestamp to every line in the stream. For magnetometer data, the timestamp is captured when the sensor’s analog measurement pulse arrives; for GPS data, it is captured from the GPS module’s PPS (pulse-per-second) signal. Because both timestamps are triggered by analog pulses and not by the arrival of digital serial data, they are free from UART transmission delay and digital jitter, and are well suited to placing records in order and correlating them with GPS time. They remain the Magpie logger’s own clock, however — see below.

Magnetometer Data Line Format

The complete format of a Magpie magnetometer line, including the prepended microsecond timestamp:

{us_ts}!{scalar}{sv}[axis]{vector}{vv}@{counter}>{ms_ts}s{s_sens}v{v_sens}[IMU]

All fields after the ! is produced by the QTFM Gen-2 sensor; the microsecond timestamp before the ! is added by the Magpie. Items in brackets are optional and depend on which print items are enabled.

• Scalar validation. An underscore _ after the scalar value means the data is valid and reliable. An asterisk * means the data is likely invalid — common causes include the sensor oriented in a dead zone, an excessive gradient field, a background field outside the operating range, or an incorrect scalar zero-crossing (sZC) setting.
• Vector validation. An equals sign = after the vector value means valid data; a question mark ? means invalid data — common causes include the sensor oriented in a dead zone, excessive gradient field, and incorrect vector zero-crossing (vZC) setting.
• Vector axis cycling. Only one vector axis (X, Y, or Z) is printed per line. The three axes cycle sequentially on consecutive lines, so the vector data rate is 3× slower than the scalar data rate.
• Data counter. A three-digit counter (0–999) that increments with each data point. A gap greater than 1 between consecutive values (except at the 999→0 rollover) indicates dropped data.

IMU Data

When an IMU control is enabled, one IMU packet is appended to the end of the magnetometer line. Each IMU type uses its own set of delimiters:

All three axes for a given IMU type are printed together on the same line. When multiple IMU types are enabled, they alternate on consecutive data lines.

GPS Data Lines

When the GPS module has a fix, the Magpie interleaves GNSS fix lines into the stream (typically once per second). A GPS line uses a comma as its first character after the timestamp:

{us_ts},GNSSFIX,{lat},{lon},{year},{month},{day},{hour},{min},{sec},{alt_m},{alt_dm}

When there is no satellite fix, the line is simply:

{us_ts},No GPS Fix

Time Synchronization Between GPS and Magnetometer

The microsecond timestamp is the key to relating GPS time to magnetometer time. Both line types share the same Magpie microsecond clock, and — critically — both timestamps are captured from analog pulse signals: the sensor’s measurement pulse (IO22) for magnetometer data, and the GPS module’s PPS pulse for GPS data. The timestamp records when each pulse fires (when the measurement is taken), not when the subsequent digital data is received, which eliminates UART transmission delay and digital jitter from the timing.

This means you can:

• Use the ,GNSSFIX line to get absolute UTC time and position.
• Use the shared microsecond timestamp to precisely correlate each magnetometer reading to the GPS time base.
• Interpolate GPS position at any magnetometer sample time, since both reference the same clock.

Worked Example: A Complete Data Stream

Below is real Magpie output showing magnetometer lines with alternating IMU packets (gyroscope and accelerometer) and one interleaved GPS fix line:

368587947!51110.868_X-18588.443=>367275s112v082i20.34j-37.74k24.27
368595950!51100.954_Y-53297.125=>367283s114v074a-739.75b55.18c-703.12
368603949!51110.174_Z95053.800=>367291s112v047i-16.28j-0.49k-30.18
368611949!51101.410_X-18944.036=>367299s112v068a-721.68b-57.13c-716.31
368619948!51109.166_Y-54146.972=>367307s113v045i-5.18j30.88k-10.49
368627948!51102.475_Z96081.626=>367315s113v044a-750.00b61.52c-716.80
368711323,GNSSFIX,399652672,-1051083328,2025,09,16,19,21,26,1615,6
368635948!51108.602_X-18907.217=>367323s112v058i1.25j-1.86k-12.96
368643949!51103.663_Y-54376.794=>367331s113v046a-732.91b5.86c-709.47

Breaking down the first magnetometer line:

368587947!51110.868_X-18588.443=>367275s112v082i20.34j-37.74k24.27

Breaking down the GPS line:

368711323,GNSSFIX,399652672,-1051083328,2025,09,16,19,21,26,1615,6

Because the magnetometer line (368587947) and the GPS line (368711323) share the same microsecond clock, this GPS reading was captured 123,376 µs (about 0.12 s) after the first magnetometer reading shown. That shared clock is what enables precise correlation between GPS position/time and magnetometer measurements.

6.2  QLog_Processor.exe (.txt → Analysis-ready CSVs)

QLog_Processor is the post-processing utility for Magpie logs; it replaces the previous flat-formatter to interpolation workflow. Drag a raw .txt log onto the executable and it writes its output into the same folder as the source log. A single pass produces four products, each named after the source file:

The three CSVs share one column schema:

|Timestamp(uS)|SensorTimestamp(ms)|MagData(nT)|Good S - Data|Data Counter|

|Scalar Sensitivity|bX(nT)|bY(nT)|bZ(nT)|Good V - Data|Vector Sensitivity|

|Latitude | Longitude | HAE(m) |UTC Date (YYYY-MM-DD)|UTC Time (H:M:S.mS)|

|AccelerometerX(mg)|AccelerometerY(mg)|AccelerometerZ(mg)| GyroX | GyroY |

| GyroZ | IMU_VMagX (uT) | IMU_VMagY (uT) | IMU_VMagZ (uT) | IMU_Temp(C) |

With the breakout board installed, the Magpie can stream sensor data over Ethernet via TCP on port 5000, accept commands inbound on the same connection, and publish in ASPN/LCM formats to a remote subscriber. Up to four simultaneous TCP clients are supported, plus an optional UDP data port on 9000 for data-only output. Ethernet is more reliable than Bluetooth or Wi-Fi for sustained high-rate streaming and is the recommended interface for survey-grade work and any deployment with PTP-synchronized post-processing.

7.1  Default Network Settings

Out of the box, the Magpie is configured as IP 192.168.10.2, subnet 255.255.255.0, gateway 192.168.10.1. The TCP data port is 5000 and the optional UDP data port is 9000. Set your PC to a static IP on the same subnet (for example 192.168.10.1) and connect a standard Cat5e or better Ethernet cable directly between the PC and the Magpie — the W5500 auto-detects polarity so no crossover cable is required.

Change the Magpie’s IP, subnet, or gateway with [eth ip …], [eth subnet …], and [eth gateway …] respectively (saved to NVS; reboot to apply).

7.2  First-time Setup

The Magpie’s GPIO IO20 is shared between the external serial port and the W5500 SPI bus, so the external serial path must be disabled before Ethernet can come up. Connect via USB serial or Bluetooth (you only need this once), then send [serial port internal], then [mode ethernet], then [reboot] to apply. After the reboot, the Magpie comes up in Ethernet mode and the boot banner shows the link state and assigned IP. Verify with ping 192.168.10.2 from your PC (replies should arrive in roughly 1 ms). The [eth status] command reports the running configuration and connected-client count.

7.3  Python Connection Tool

QuSpin ships a small command-line tool, mini_acb_ethernet.py, in the firmware repository’s tools/ folder. It connects to the Magpie over TCP, can log incoming data to a timestamped file, optionally parses binary packets, and runs PC-side ASPN conversion. Python 3.6 or later is required; no third-party packages are needed (standard library only). Typical usage:

python mini_acb_ethernet.py

connects to 192.168.10.2:5000 in quiet mode. Useful flags: --data (show every data line), --log (immediately start logging to a timestamped file), --binary (parse binary packets — use when [eth binary on] is set on the Magpie), and --aspn [--aspn-version 2023|3.0] (run ASPN conversion on the PC side, the recommended path in binary mode). Once connected, anything typed at the prompt is routed to the Magpie just like Bluetooth or USB Serial.

7.4  ASCII vs Binary Data Formats

By default the Ethernet stream is ASCII text, identical to what you would see on Bluetooth or USB Serial — see the Data Output chapter for details. Switch to binary with [eth binary on] when bandwidth is constrained or you want a fixed, parser-friendly packet shape. The binary packet layout is:

[0xAA][0x55][type:1][len_LE:2][ts_us_LE:8][payload:N][xor_chk:1]

7.5  ASPN Output

ASPN (Airborne Survey Protocol for Navigation) is a YAML-based standard format for magnetometer survey output. Enable on-device ASPN conversion with [aspn on] (ASCII mode only). For binary mode, run the conversion on the PC side via the Python tool’s --aspn flag — this avoids the bandwidth and on-device CPU cost of multi-line YAML inside the binary packets. GPS position publishes as an ASPN GeodeticPosition 3D record (ICD 1001.3), including altitude; a legacy 2D format is available via [gps_format 2d].

7.6  Ethernet Troubleshooting

If ping fails: verify the cable, confirm the PC’s IP is on the same subnet, and check that the serial port was set to internal before Ethernet boot. Boot banner showing ETH HW: NoHardware means the W5500 was not detected on the SPI bus — usually an IO20 conflict (re-send [serial port internal] and reboot) or a hardware issue with the breakout board. ETH LINK: DOWN means no cable or a faulty cable. Connections that drop briefly right after a command are expected; the Python tool reconnects automatically.

There are two updatable firmware images inside every Magpie which update independently. The Magpie / MiniACB logger firmware (Wi-Fi, Bluetooth, SD card, Ethernet, etc.) is updated from the Magpie itself; the QTFM Gen-2 sensor firmware is updated through a flex-cable connector on the side of the MiniACB board using a standard QuSpin Comms board. The two procedures use different files and different cables — check which firmware QuSpin has asked you to update before starting.

8.1  Updating the Magpie / MiniACB Logger Firmware

The logger firmware can be flashed two ways: Wi-Fi OTA (recommended for most users) or a USB UART flash using ESP32_Flasher.exe (a recovery path that works even when Wi-Fi is unavailable).

Method 1: Wi-Fi OTA (Recommended)

1. Power the Magpie on and connect your computer or phone to the Magpie Wi-Fi access point (default password 12345678).
2. Open a web browser to http://miniacb/ and scroll to the firmware upload section at the bottom of the page.
3. Click Choose File and select MINI_ACB_V<N>.ino.bin (no need to rename the file).
4. Click Upload. Wait for the upload to finish, then send [update] from the page’s logger-command panel to apply the update and reboot.

Method 2: USB UART Flash (Recovery)

If the Wi-Fi OTA path is unavailable (first time setup, recovery from failed OTA, or as release notes specify), use the ESP32_Flasher.exe Windows tool over the Magpie’s USB port.

1. Connect the USB cable, launch the flasher and connect to the new COM port.
2. Configure the flasher window:
   • .bin — select MINI_ACB_V<N>.ino.merged.bin
   • Flash Address — set to 0x0 - Merged all-in-one firmware (bootloader+part+app)
   • Baud Rate — leave at 921600 (default)
3. Click ”Flash ESP32“ and wait. Once --- Finished --- appears, disconnect.
4. Open the QTFM2 UI, http://miniacb/or any serial terminal and send the string [refresh_sn]. You will see an output like: #Serial Number: T2M0-00NB
Notes
• [refresh_sn] renames the Magpie’s Bluetooth and Wi-Fi identity. To reconnect, first remove the old Bluetooth pairing or the forget previous the Wi-Fi network, then follow the connection steps in Setup.
• MiniACB firmware V5_10+ only If the sensor LED shows connected (blinking blue) but the startup banner doesn't appear, then [refresh_sn] may have run automatically after the flash. Disconnect and reconnect to the Magpie.

8.2  Updating the QTFM Gen-2 Sensor Firmware

The QTFM Gen-2 sensor that lives inside the Magpie has its own firmware, separate from the MiniACB logger. It is not flashed over Wi-Fi or USB; instead, every MiniACB board exposes a small flex-cable connector on its side that connects directly to the sensor’s programming pins. Plug a standard QuSpin Comms board into that connector and update the sensor firmware exactly as you would on a bare Gen-2 sensor. You will need to remove the outer Magpie shell to reach the connector, but the sensor itself stays mounted in the internal sled throughout.

Procedure (Summary)

1. Power off the Magpie and remove the outer shell so the MiniACB board is accessible. The sensor itself stays mounted on the internal sled — do not separate it from the sled.
2. Connect the standard QuSpin Comms board to the flex-cable connector on the side of the MiniACB board (see Everyday Operation).
Note Older sled versions will require the MiniACB be unscrewed to access the connector.
3. Plug the Comms board into your PC over USB and follow the QTFM Gen-2 firmware update procedure. The Magpie’s logger does not need to be running during this process; the sensor is reflashed directly through the Comms board.
4. Disconnect the Comms board, slide the sled back into the shell, and power the Magpie on. The new sensor firmware version appears in the boot banner.

Routine hardware tasks you will perform in the field: powering the Magpie from its battery, opening the outer shell, and removing the SD card.

9.1  Battery Operation

To connect the included 11.1 V, 1800 mAh 3S Li-Po battery pack:

1. Confirm that the red battery adapter is fully seated and secured.
2. Align the white male Magpie connector (M) with the female battery connector (F).
3. Push the connectors together firmly until they click into place.

To disconnect the battery:

1. Locate the connector closest to the Magpie sled (M).
2. Squeeze the locking tab down against the connector body to release it.
3. Pull the battery-side connector (F) straight out; it should release with minimal force.

9.2  Removing the Magpie Shell

Removing the Magpie’s outer shell is necessary for several tasks, including removing the SD card, updating firmware, and accessing the internal boards. To remove the shell, insert a screwdriver through the provided hole and use it as a handle to pull the sled free of the shell.

9.3  Removing the SD Card

The Magpie logs all recorded data to the SD card; remove it to read your data directly on a computer or to swap in a fresh card. First remove the outer shell (see Figure), then locate the SD card slot on the MiniACB. To release the SD card holder, gently push it away from the edge of the Magpie; the holder will pop up.

9.4  Hardwiring with a Standard Comms Board (SCB)

A standard QuSpin Comms board (SCB) plugs into the flex-cable connector on the side of the MiniACB for a direct serial link to the sensor — useful for updating sensor firmware.

1. Remove the Magpie shell and locate the flex-cable connector on the side of the MiniACB board, pictured above.
2. Connect the SCB via flex cable to the MiniACB, then power the SCB with a data micro-USB cable.
3. Open the COM port in the QTFM2 UI or any serial monitor.

As an alternative to the battery and sync cables, you can also power and communicate with the Magpie through a Comms board over a single micro-USB cable — see Hardwiring Magpie inputs with a standard comms board.

If you need to assemble your Magpie, follow the steps below.

The Magpie is built around a central sled that carries its electronics and sensor. The labeled breakout below identifies the components referred to throughout this chapter.

Procedure

1. Lay out the components, tools, and hardware:

   Category	Items
   Magpie Components	Magpie sled Charge protector board with input cables ECU External GPS adapter cable (black) Internal GPS antenna with cable (white) MiniACB QTFM2 sensor head Magpie outer shell
   Vector Add-on Components (optional)	Vector coil add-on top board Vector coil flexible printed circuit (FPC)
   Tools and Hardware	Tweezers Screwdriver Double-sided tape 6 × M2-0.4×6 mm screws

2. Apply double-sided tape to the sled in the areas beneath the ECU and sensor head, but do not peel off the top layer yet.
3. Slide the input cables through the open end of the sled and fasten the charge protector board to it with two M2-0.4×6 mm screws. To install different cables, see Integrating Alternate Cables.
4. Connect the ECU to the charge protector board’s flex cable; it should sit on the taped area. Tuck the external GPS adapter cable (black) underneath the ECU. Refer to Figure for ECU orientation.
5. Connect the external GPS cable (black) to the UMCC port on the bottom of the MiniACB, then attach the MiniACB to the ECU.
6. Peel off the top layer of the ECU tape and press the ECU and MiniACB into place. Confirm that the mounting holes on the MiniACB align with the sled’s screw holes, then fasten the MiniACB with the remaining four screws.
7. Connect the sensor head’s flex cable to the ECU. Connect the internal GPS antenna (white) to the MiniACB’s top UMCC connector.
   Vector coil add-on If installed, attach the vector add-on board to the top of the MiniACB and connect the vector coil FPC to its flex port. See Vector Coil Installation below for more details.
8. Peel off the top layer of the sensor head tape and press the sensor head into place.
9. Slide the outer shell onto the sled.

Vector Coil Add-on Installation

The vector coil add-on adds three-axis (vector) magnetic-field readout on top of the Magpie’s scalar QTFM2 sensor. On vector-equipped units the coil FPC's wrap around the sensor head and the vector electronics board mounts on top of the MiniACB.

1. Power off the Magpie and remove the outer shell so the sensor and MiniACB are accessible. Remove the sensor from the sled.
2. Take the vector coil flexible PCB and remove the adhesive backing from the five sections indicated.

   

3. Align the vector coils from the top of the sensor, opposite the serial number. Wrap the coils around the sensor head and firmly press into place.

   

4. Snap the vector top board onto the MiniACB, then attach the vector coil flex cable to the flex connector on the vector top board. Make sure the board seats fully and sits flush against the MiniACB.

   

5. Tape the folded coil edges down with Kapton tape so they do not catch on anything during use.

   

6. Return the sensor to the sled and slide it back into the outer shell.

The 2-pin + 6-pin breakout board that ships with every Magpie carries battery power on its 2-pin cable and exposes the sensor’s serial UART and synchronization lines on its 6-pin cable. It is the primary way to integrate Magpie into custom platforms, hard-mounted deployments, multi-sensor arrays with a shared 1 PPS, and any setup that needs a wired serial connection to the sensor (for example Ethernet streaming via the W5500 module, USB-UART data capture, or driving an External PPS Sync array).

Both cables use Julet M6 waterproof connectors. The 2-pin cable mates directly with the standard Magpie power cable’s opposite end; the 6-pin cable has six individually-colored conductors at its open end.

Pin / Wire-color Map

* On older input cables the Sync_input conductor was blue rather than orange.

Notes on the Signal Lines

UART logic levels are 0–3.3 V (3.3 V CMOS) and the default Magpie baud rate is 921600 bps, 8N1. When wiring to a host or USB-UART adapter, connect the host’s TX to White and its RX to Red, then tie Black to the host’s ground. To stream Magpie data directly out of this UART port and send commands over the external UART, send [serial port external].

Sync_Input and Sync_Output are 3.3 V logic signals. For wired Master/Slave sync, run a wire from the master’s Sync_Output (Green) to the slave’s Sync_Input (Orange) and tie the two Blacks together. For External PPS Sync, fan the same external 1 PPS source (typically a 0–3.3 V GPS PPS line) to every sensor’s Sync_Input (Orange) and tie all the Blacks together. See Time Synchronization for the full setup of each method.

If you damage the connector or open end of the cable, the spare female 6-pin Julet M6 connector included with every Magpie shipment can be soldered or crimped on to rebuild the cable. The 2-pin spare connector serves the same purpose for the power cable.

Hardwiring Magpie Inputs with a Standard Comms Board (SCB)

As an alternative to the two cables, the spare 2-pin power and 6-pin breakout connectors can be wired to a standard QuSpin Comms board (SCB). A single data-capable micro-USB cable then supplies power to both the Comms board and the Magpie, and provides the external serial link. This configuration is recommended when battery operation of the Magpie is not needed. Wire the connectors to the labeled Comms-board pads as shown, then set the serial port to external using [serial port external]. See the Magpie Command Guide for the full command reference.

1. Remove the Magpie outer shell (see Removing the Magpie Shell in Everyday Operation).
2. Remove the two M2-0.4×6 mm screws nearest the connector cables (highlighted in Figure).
3. Flip the hinged flex-cable connector upward and disconnect the flex cable (Figure).
4. Remove the charge protector board and input cables from the Magpie sled to expose the underlying wires (Figure). Feed the two input ports through the Magpie sled one at a time.
5. Use the wire-color reference below to match each wire to its pad.
6. Desolder the existing cables and solder your replacement cables to the corresponding pads.
7. Apply and heat 5/8″ heatshrink around your replacement input cables.

Wire-color Reference

Wire colors are consistent across units; the power cord connects to the V.in (RED) and GND (BLK) ports at the base of the board.
* On older input cables the Sync input conductor was blue rather than orange.

13.1  Internal GPS Antenna

Magpie ships with the internal passive flex GPS antenna pre-connected as shown above. For most users and deployments, an external GPS antenna is not required. When the unit is operated outdoors with a clear view of the sky, it will begin acquiring satellites and should achieve GPS lock automatically.

13.2  Connecting an “Active” External Antenna

To use an active external GPS antenna — such as when operating in environments with limited sky view, when the internal antenna cannot achieve reliable lock, or when using a carbon-fiber shell — you can switch Magpie from its internal passive (flex) antenna to an external active antenna connection. Magpie ships with the external adapter cable disconnected and taped to the sled; leaving the cable plugged in alongside the internal antenna creates RF interference that significantly extends GPS lock time. To switch to the external configuration, open the Magpie shell, disconnect the internal passive GPS flex antenna, retrieve the external adapter cable from where it is taped to the sled, and connect the cable’s UFL plug to the GPS receiver (either of the two GPS receiver ports). Then install the provided 2-pin jumper to enable the active-antenna power path.

Reinstall the plastic or carbon-fiber shell onto the Magpie sled, and connect your external antenna to the MMCX (female) jack on the outside of the Magpie.

13.3  Connecting a “Passive” External Antenna

If you want to use your own passive external GPS antenna (typically a flex-style antenna), Magpie can route the GPS signal to the external MMCX port without enabling active-antenna power. Open the Magpie shell and disconnect the internal passive (flex) GPS antenna. Then remove the 2-pin jumper (leave it disconnected). Next, locate the external adapter cable on the bottom side of the PCB, unplug it, and reconnect it to the top-side UMCC connector. Reinstall the shell and connect your passive antenna to the external MMCX (female) jack on the outside of the Magpie.

This setup differs from the active configuration in one key way: a passive antenna does not include an amplifier and does not require power from Magpie, so the jumper must be removed and the signal routed through the UMCC connection path. For best results, mount the passive antenna on a non-conductive, rigid surface with a clear view of the sky. If you mount the antenna on the outside of a carbon-fiber shell, place several layers of non-conductive tape between the shell and the antenna to help reduce signal attenuation.

14.1  Physical & Electrical

14.2  QTFM Gen-2 Sensor Head

14.3  Integrated Modules

Magpie’s MiniACB logger and Windows user interface accept configuration and control commands using a simple bracketed protocol. Each command must be sent enclosed in square brackets ([ … ]). Main command keywords are case-insensitive (for example, [PTP ON] and [ptp on] perform the same action), but command arguments — such as filenames — may be case-sensitive and should be entered exactly as intended.

15.1  General System Status

15.2  Data Logging Control

15.3  PTP Time Synchronization

15.4  Serial Streaming Mode

15.5  Connectivity & Modes

15.6  Advanced Sensor Processing (ASPN)

15.7  Heartbeat Settings

15.8  SD Card Management

15.9  Debug & Tweak Tools

15.10  GPS

15.11  Wireless GPS Sync (Magpie → Sensor)

15.12  Networking (Ethernet and TCPService)

15.13  LCM Channels and ASPN Device IDs

Override the published-channel names and ASPN device-ID URIs for the five logical streams (total_field, threeaxis, imu_vmag, inertial, gps). Defaults are MAGPIE_* channel names and sdm://magpie/<SN>/<icd>/<topic> URIs.

15.14  Diagnostics, Profile & Miscellaneous

15.15  Passthrough Commands

The Magpie’s command parser recognizes three distinct command forms and routes each to a different destination.

Magpie is built around the QuSpin QTFM Gen-2 sensor and supports the full QTFM Gen-2 serial command set for configuring sensor behavior, selecting operating modes, managing startup behavior, enabling filters, toggling vector or scalar mode, and accessing diagnostic information. The single-character ASCII commands can be sent through the all-in-one QuSpin Windows software, the MiniACB browser terminal, the Android app, or any standard serial terminal. Sensor commands are forwarded to the sensor when left bare (single characters) or wrapped in tildes (strings) — for example, a bare s prints the sensor’s startup settings, and ~Start~ enables autostart on power-up (see Passthrough Commands in the Magpie Command Guide). For the complete and most up-to-date sensor command reference, see the QTFM Gen-2 Quick Reference (every command in one grouped table) and the QTFM2 Sensor Profile Configuration guide (built-in profiles and custom slots) on the QuSpin website.

The Logger and Sensor LEDs are found on the Magpie sled, marked “L” and “S” respectively. The Sensor LED communicates magnetic data quality (idle, valid measurements, or conditions such as high gradients or dead zones). The Logger LED reflects recording status and GNSS lock.

17.1  Logger LED Codes

17.2  Sensor LED Codes

The Magpie’s console emits one of three line types: status (prefixed with #), magnetometer data (prefixed with a microsecond timestamp and !), or GPS / IMU records (timestamp + , or other tag). Every status line is informational unless it starts with the word ERROR. WARNING lines are advisory. This section catalogs the messages an operator most commonly sees, grouped by category.

18.1  Boot and Initialization

Status lines you see immediately after the Magpie powers on. The boot banner ends with #Ready — once that prints, the Magpie is ready to take commands and stream data.

18.2  Saving Data to the SD Card

18.3  Save WARNING Messages

Pre-flight and post-flight warnings designed to make silent-failure saves visible. These do NOT halt the save — they tell you the save will likely be empty or interrupted so you can act before too much data is lost.

18.4  Diagnostic Counters

18.5  GPS, PTP, and Wireless Sync

18.6  Errors and Stop Conditions

18.7  Sensor Passthrough Lines

When the Magpie is connected to a QTFM sensor, the sensor’s own output passes through unmodified. These lines come from the sensor, not the Magpie.

If the Magpie will not complete autostart, keeps rebooting with #Laser Overheated, or continuously reports #Laser Unstable, the QTFM Gen-2 sensor inside it may need reoptimization. The sensor firmware includes semi-automated routines — run from the QTFM2 UI terminal — that restore it to optimal operation.

20.1  Preparation

1. In the QTFM2 UI, connect to the Magpie over Bluetooth.
2. Open the Terminal and Advanced Settings tabs.
3. Filter the Terminal display by “Status,” then click “Print Parameters” to view the current system state.
4. Review the values: no parameter should read 0 or -1 (that indicates an overwritten value). In particular, confirm CH_Prop_Gain (262) and CH_Int_Gain (263) are not 0.00 — these are not restored by the automated routines. If either reads 0.00, use “Mem Write Float” to set memory address 262 to 30.00 and address 263 to 0.005.

20.2  Basic Settings Reoptimization

1. Click “Auto Optimization 1” to start the first routine. It takes about 30 seconds (Sensor LED purple) and reboots twice into autostart.
2. Watching the Terminal, wait for autostart to complete (#Autostart Complete) and the cell to lock (#Cell Locked).
3. Click “Auto Optimization 2” to run the second routine (~30 seconds, LED purple). After it reboots, click “Save Auto Parameters” to write the new values to memory.

20.3  Laser Gains Reoptimization

1. With the sensor operational and locked, click “Laser Optimization”. Expect several #Laser Unstable messages; wait for #Laser Stable before continuing.
2. Move the sensor head all around (simulating a moving platform). This may trigger more #Laser Unstable messages; keep moving the head and wait for a final #Laser Stable.
3. Click “Save Laser Parameters” to calculate and store the new laser gains. If no #Laser Unstable message appears after about a minute of moving the head, proceed to saving the parameters.

20.4  Vector Coil Optimization

Units with the vector add-on calibrate the vector coil separately so the Bx/By/Bz outputs track correctly. This routine requires sensor firmware V1_36 or later.

1. In the Terminal tab, confirm autostart is complete and the cell is locked. For best calibration results, allow the sensor to run for about 5 minutes before proceeding.
2. Verify the sensor is in vector mode and that the X, Y, and Z outputs are valid.
3. In the Manual Command tab, send command 6 with “Send Decimal”. The sensor responds #Calibrating Coil, keep sensor still. — Calibration typically takes 1–2 minutes.
4. When it finishes, the terminal prints the measured deltas, for example #Delta_X:12040, Delta_Y:6900, Delta_Z:5954.
5. Send command 9 with “Send Decimal” to permanently store the calibrated vector-coil values in the sensor’s memory.

If the sensor cannot complete this process, or does not operate as expected after these steps, contact QuSpin technical support at info@quspin.com.

Use the following practices to maximize data quality and reduce field issues:

• Keep the sensor head away from ferrous materials and current-carrying electronics.
• Maintain a consistent sensor orientation during a survey. If the Sensor LED indicates a dead zone or bad data, re-orient or relocate the instrument.
• Avoid mounting near high magnetic gradients and fast field changes (near vehicles, large steel objects, motors, or transformers).
• Allow the system to reach a stable temperature before critical measurements.
• Use a clean, stable power source (battery recommended) and secure all cables with strain relief.

After-use Check (Especially After Wet, Dusty, or Cold Conditions)

• Power off and disconnect the battery.
• Wipe down and dry the exterior.
• Slide the sled out (see Removing the Magpie shell) and inspect the gasket area and shell interior for moisture or debris.
• If moisture is present, allow the unit to dry completely before reassembly. Use dry air or desiccant; do not use high heat.
• Reinstall the sled, confirm the gasket seats evenly, and store at room temperature or slightly cooler.

Water-Resistant Sealing

1. Locate the provided 1″ section of 5/8″ 4:1 adhesive-lined heat-shrink tubing, or cut your own. 
Note The provided tubing is adhesive-lined; However, to improve water resistance, we recommend applying silicone caulk inside the sled's connection port (between the 2-Pin and 6-Pin cables) before shrinking the tubing.
2. Slide the tubing over the input cables and up against the Magpie sled.
3. With a heat gun set to 80–85 °C (176–185 °F), shrink the tubing against the Magpie sled first, then work along the cables to complete the seal.

Follow these guidelines to protect the instrument and maintain measurement quality:

• ESD: Handle the sensor head and electronics as ESD-sensitive components. Before connecting accessories, discharge yourself by touching a grounded metal object, and avoid contact with connector pins.
• Magnetics: Keep ferromagnetic objects (steel tools, phones, laptops, keys, vehicle parts) away from the sensor head during operation. Magnetic contamination and local gradients can corrupt measurements and may trigger “bad data” LED states.
• Environment: Avoid strong magnetic fields, rapid field changes, and high gradients (near motors, transformers, speakers, vehicle bodies, or large steel structures). Reposition the instrument if the Sensor LED indicates a dead zone or bad data condition.
• Moisture: Keep Magpie dry. If exposed to rain, spray, or condensation, power it off, disconnect the battery, dry the exterior, and allow it to fully air-dry before reuse. Do not use a heat gun or open flame.
• Power: Use only a clean, stable DC power source within the specified voltage range. Electrical noise or unstable power can increase measurement noise and cause logging errors.
• Temperature: Operate and store the unit within the temperature limits listed in Technical Specifications. Allow sufficient thermal stabilization time before making critical measurements.

Removing the Housing

Locate the external hole on the Magpie shell. Insert a screwdriver shaft through the hole and gently pull the shell away from the screwdriver to free the sled.

For support, contact the QuSpin support channel provided with your purchase or your QuSpin representative. When requesting support, include:

• Magpie serial number
• Firmware/build information (use “Print sensor info short” or “Start-up settings”)
• A short description of the issue and LED states
• A data snippet or log file (if available)