BN-880 Compass On Lattepanda Leonardo

Yes - the LattePanda’s onboard Arduino Leonardo is compatible with the BN-880 skill’s Arduino firmware, but the important detail is that the BN-880 compass uses I2C on the Leonardo’s hardware I2C pins, not the serial pins, so your wiring and sketch must match that exactly.

What should work

For the LattePanda Leonardo, use:

• BN-880 TX Leonardo D0 (RX)
• BN-880 RX Leonardo D1 (TX)
• BN-880 SDA Leonardo SDA
• BN-880 SCL Leonardo SCL
• BN-880 VCC 5V or 3.3V depending on your BN-880 breakout version
• BN-880 GND GND

So the fact that you used the dedicated SDA/SCL pins near RST is correct for the Leonardo. On the Leonardo, those are the hardware I2C pins.

ARC / COM / DTR settings

For the BN-880 skill in ARC:

1. Add the skill from Project > Add Robot Skill
2. Open the skill’s kebab/hamburger menu on the top right
3. Select the COM port for the LattePanda Leonardo
4. Use the baud rate specified by the Arduino firmware that came with the skill
   • If the firmware package says a specific baud, match that exactly
   • The GPS serial side is often 9600, but the Arduino-to-ARC link is whatever the firmware expects
5. Enable DTR in the connection config, since the LattePanda Leonardo USB serial driver needs it

Why the heading may stay at 0

What you describe usually means one of these:

• The I2C compass is not initializing correctly in the firmware
• The magnetometer type/address does not match the firmware
• The sensor is returning data, but the heading calculation is failing
• The compass is being affected by magnetic interference from the robot, motors, power wiring, or nearby metal

Since your standalone QMC5883L sketch works, the hardware side is probably fine. That makes me suspect the BN-880 skill firmware is not matching your magnetometer variant or initialization sequence.

Very important BN-880 note

Not all BN-880 boards use the same compass chip behavior. Some boards are:

• QMC5883L
• HMC5883L-compatible
• or clones with slightly different I2C behavior

If the skill firmware was written for one chip but your module behaves like another, you can get exactly what you’re seeing:

• GPS works
• heading stays zero
• calibration won’t stick or seems ignored

What I’d try next

1) Confirm the Arduino firmware is loaded from the skill package

Use the exact firmware from the BN-880 skill page:

https://synthiam.com/Support/Skills/Navigation/BN-880-GPS-Compass?id=21348

If you modified it for 0x0D, make sure the rest of the initialization still matches the board. A partial tweak can sometimes break the startup sequence.

2) Test with the board isolated from the robot

Run the BN-880 away from:

• motors
• motor controllers
• power wires
• batteries
• speakers
• steel plates or brackets

Even a working compass can look dead if interference is strong.

3) Verify the compass is really the chip expected by the firmware

Since you already have a working QMC5883L test sketch, that strongly suggests the module is QMC-based. If the ARC firmware is expecting a different chip or register map, the heading won’t behave.

4) Check whether the skill has a calibration flow that requires saving

Some skills show a Calibrate button but don’t actually persist calibration unless:

• the skill is connected
• the sensor is detected
• the calibration routine completes
• then the values are written/retained

If the sensor isn’t initializing, calibration often appears to do nothing.

Bottom line

• Yes, the LattePanda Leonardo I2C pins are correct for the BN-880 compass
• Yes, DTR should be enabled
• No, baud rate alone usually won’t fix a heading stuck at 0
• Your symptoms strongly suggest a compass chip initialization / compatibility issue or magnetic interference, not a GPS issue

Best next step

If you want, I can help you narrow this down by checking one of these:

1. Your exact BN-880 breakout chip and whether the firmware should be QMC5883L-specific
2. A simple Arduino sketch for the Leonardo that reads the compass and prints heading values so we can compare against ARC
3. How to adjust the BN-880 firmware or convert the logic into a custom ARC robot skill if the stock one isn’t matching your board

If you want, I can also give you a known-good Leonardo wiring and test sketch for the BN-880 so you can confirm heading before bringing ARC back into the loop.