No motherboard response

Today my Raspberry stopped communicating with the motherboard. Assuming that I have two Magni robots and tested my Raspberry, it works. I tried with my oscillator and the Raspberry receiver uart port does not receive any signal. Could it be a firmware problem and if it is, how do I update if I don’t get any response from the card?
another information is that I launched the bringup.launch node but it fails to compile because I get the error “unrecognized firmware”

what you describe is most always a failure in the serial level translators which are tiny parts called U1 and U2. The ‘unrecognized firmware’ message is almost always failure of the Raspberry Pi to communicate with the main board on the Magni.

Please tell me the version of your MCB (in big white letters on left edge of the board as you look at the top of the board). Also tell me if you are using the P508 FTDI jack at all which is a debug serial port that can impact these lines if it is used incorrectly.

We have a very extensive document for troubleshooting but I will paste in a small segment if you have troubleshooting equipment.

Be sure the 3.3V is available for the level translators by seeing the 3.3V led near P507 as strongly blue or this issue can be broken 3.3V power but in that case the OLED display would be not on as well.

Here are tips to verify each translator is working. The signal names here match the silkscreen on 2-pin P507 and 5-pin FTDI connector (back of board) called P508.

  • You see 3.3V 38400 baud signal on HTX but no 5V serial on RX line of P508. Failed U1
  • You see 5V serial on TX line of P508 but no 3.3V serial signal on P507 HRX. Failed U2

The full document I am unable to attach so send email to and in the subject put ATTN Mark then requiest the MCB to raspberry Pi full troubleshooting document which has not made it to our ‘learn pages’ in full at this time.

Thank you for your response and support. Here are further details regarding the situation:

  • The 3.3V LED is not working, but we confirm that the Raspberry Pi correctly generates the 3.3V voltage. We measured this voltage at points P702 and P704.

  • the board is 5.1 version

  • On port P507:

    • We have a 3.3V signal at 38400 baud outgoing from the Raspberry Pi (TX).
    • However, we do not detect any incoming signal (RX).
  • On port P508:

    • We do not detect any outgoing signal (TX).
    • We detect an attenuated signal of 400 mV incoming (RX).

These details should help you better understand the situation. We remain available for further instructions and assistance in resolving this issue.

Thank you again for your support.

Revision 5.1 did not yet have the onboard 5V to 3.3V converter so you would not have the 3.3V led.

Please now tell me the serial number of the main board which is on a white sticker on the MCB top, easy to see. Some earlier boards were lacking that so just say ‘not there’ if you don’t see the sticker.

From your reply we now check a couple more things.

  • Verify the ‘STAT’ led (to far right of 5 leds) is blinking all the time.
  • Verify the 5VM led in the middle is on and bright.
  • If STAT is not blinking but 5VM is on solid, measure on the ‘MAIN’ 4-pin molex jack at top of board that 5V has on it 5V.

We had some failures in the past that if no 5VM and if you have some proper surface mount rework equipment then try removal of rather big 5mm x 3mm diode labeled on your board D303_5M. This diode is about 30mm below the 5V pin on the MAIN power molex jack. This diode had component failures that led to the 5V supply not able to start and it sometimes failed well after shipment of the unit. We have fixed this issue on current boards.

Hi mjstn2011,

Thank you for your ongoing assistance. Here are further details about the current situation:

  1. The board version is 5.1
  2. The serial number of the board is 3935sm020.
  3. The ‘STAT’ LED on the board isn’t blinking; it remains off steadily.
  4. The ‘5VM’ LED is steadily on and bright.
  5. We’ve measured the voltage on the 4-pin ‘MAIN’ connector at the top of the board, and it shows 5V.

However, there’s an additional issue: when we power the robot, the power button doesn’t work, and the LEDs never turn off unless we completely disconnect the power. This issue occurs whether we connect only the batteries or only the power supply with the batteries disconnected.

Thank you once again for your ongoing support, and we’re looking forward to instructions on how to proceed in resolving this issue.

Best regards, Augusto Capone

The ‘STAT’ Led is driven by the MCB onboard processor. If your 5VM is on and you measure 5V at the ‘MAIN’ power jack then the onboard processor is broken. This can happen in a failed firmware upgrade, was a firmware upgrade attempted just before it stopped working?

The problem with the power switch not able to shutdown power is a faulty main power ECB (Electronic Circuit Breaker). If you are saying the RED button seems to have no effect that is the motor power switch and we have seen it fail on rev 5.1 boards a couple times before. We have only seen the Black switch (Main Power) fail once but we have seen in on rev 5.1 units.

Both of these problems can sometimes be brought on by some form of electrical stress to the MCB. We started coating our MCB board with conformal coating with rev 5.2 boards because it is so easy to have a cable or screw fall onto the board and we used to see many failures from accidental causes so we coat the boards to make it now very rare.

The revision 5.3 boards have had updates in the hardware to ‘harden’ the Motor 2 ECB circuits as well as the main power MosFet ‘switch’ on both main and motor power sides. We rarely see failures now in those ECB circuits.

Also of note is the rev 5.2 and beyond boards are the only boards that support the Raspberry Pi 4 processor because of changes to the Pi4 power requirements we cannot support Pi4 on MCB 5.1

Your unit is likely well past factory warenty but I don’t know if you got a service contract.

Please contact if you wish to get an upgraded rev 5.3 board.

Take Care, Mark