Cannot connect to power board

Hello, previous I can control the motor using CP2102 module from the P701 raspberry pi pinout to my PC. But this morning I start to receive the error “The Firmware not reporting its version”. And now the robot can be moved manually when the main power and motor power are turned on. Previously the wheels are not allowed to freely rotate when the power is turn on.

I have try the CP2102 module on another magni robot and it works well. So definitely something is wrong on the main board of the first magni. May I know do you all have the experience like this before?

We will do two quick checks to help us locate the reason for this problem.
All of what I am saying here is located in ‘Part 1’ of our verification page as well but I will ask here as well.

1st Check: If you have a version 5.0 or later board we can see if the circuit that enables motor power is active. All Magni units except very early units will have a blue led in the lower right of the MCB board to tell if motor power really goes on and off. See if a blue led turns on when the RED motor power led goes on.

Please also check the MCB board version which in recent units is in large white silkscreen on left edge of the board. If you don’t see the version please use this page:

Power Supply and Status Leds: See the ‘Master Control Board Led Indicators’ section just a bit more than half way down on this page:

See that all leds are operating described especially if the ‘STAT’ (status) led blinks.

We will then take action after your observations.

It is also possible that the battery is just low enough so we disable motor power but still keep the raspberry Pi active. If you have some way to verify that the batteries are over 22V for total voltage that would be helpful just in case they are very low but still high enough to keep the raspberry Pi alive.

Sorry you hare having trouble.

Also: If you have a sonar board and it was mounted with the middle standoff used that leads to crazy intermittent power issues. Please if you have a sonar board see this post I made:

The MCB version is 5.1. The motor led and status led are blinking. (It is shown in the first attached picture) I suspect there is not power from the P701 because the red led on the CP2102 didn’t turn on.

We don’t have sonar board for both magnis.

Below is the second magni with MCB version 5.2. The led on CP2102 turn on when I turn on the main power and motor power.

All that you are describing for the rev 5.1 MCB matches for when the 3.3V power on the Raspberry Pi is not powering the circuits on the MCB OR one of the serial drivers has failed. We saw both of these sorts of things couple times (out of over 100 boards) so starting with rev 5.2 we now have an on-board 3.3V regulator. That was a reliability improvement and also allows us to power other things like an on-board OLED display and future circuits not yet released.

We will send you a replacement MCB board and would like the rev 5.1 board back so we can use it here if it repairs.

There is some chance that your Raspberry Pi has lost it’s 3.3V output OR that output failed and led to this issue. I suggest you remove the Raspberry Pi as a first step and on your bench start it up with a typical Raspberry Pi 2Amp micro usb adapter. Then measure the ground to 3.3V on the raspberry Pi to see if the Pi is part of this failure.

Here is process for removal of the MCB:

Please send an email to and in subject please say ATTN Mark and something like MCB replacement.

In that email give a physical mail address that could accept a box with another MCB.

If you happen to be in the Bay Area of California, USA we could arrange a faster swap of the boards in the next few days.

I await the email, sorry for your troubles. We do make improvements to designs and thus look at every failure. That is how we have come to put other reliability and serviceability improvements in both rev 5.2 and 5.3. It is mostly for this reason we want the broken board back.

Stay Healthy,