I have been using a Reach M2 successfully in my agricultural development project for some time. The M2 unit is several years old and has been the crash test dummy during the project development. I can’t guaranteed that I have not done nasty things to it along the way. For about a year now the M2 has been connected to a Raspberry Pi3B via the micro USB port for data with the power line disconnected. A PiJuice HAT and 6000mAhr battery supplies 5V power via the S1 connector. This ensures that the M2 does not see power from two sources. The Emlid LoRa radio unit is connected via the S2 connector. About 2 weeks ago doing some trials to test my rPi software changes, I could not see the M2 data coming into the rPi. After some investigation I found that the M2 was not booting. Orange light only. More investigation and testing as well as replacing the old M2 with my much newer spare yielded the following.
The old M2 will not boot when powered via the S1 connector.
The old M2 will boot when powered via the micro USB connector.
The new M2 will boot in both situations under identical conditions.
I have concluded that I have damaged the old M2, but am mystified that it will still boot OK when powered via the micro USB.
Since this development project is expected to result in a product one day I would like to know if others have had similar problems with long term use supplying power via the S1 connector.
Should I reconfigure so that power is supplied via the Micro USB?
Have you measured the expected 5v on the S1 port?
Yes I have. varies b/w 5.13 and 5.15Vdc on both units.
Interestingly when the old M2 does not boot the maximum current draw is much less than when it boots from the micro USB or from earlier testing when it was OK via with the S1 connector.
When it does not boot, the max current is around 0.25Amp.
When I measure the current when either units Boot the max is between 0.5 and 0.6Amp. Voltage does not go below 5.12Vdc. I am thinking that a new resistance has developed on the S1 side of the 5V rail in the M2. I have always thought that when an M2 failed, it would not do anything at all.
Just a quick question to double-check: do you use the same cables with the old M2 and the new M2 for tests with the S1 port? Just so we know that it’s not a cable issue of some sort.
Yes Polina, I used the same cables, same power supply setup for both tests on the S1. I have been caught out before assuming that cables and supply were not involved.
The problem could be in the S1 socket on the M2. I have not gone to point of opening the M2 case to investigate this possibility.
Ok, I see. Let’s not open the device at the moment. Give me a bit of time to quickly consult with our engineers on it, please.
Can you please check if you can power up the unit from S2, C21, or C2 connectors? This is essentially a check on the cable, as it may cause issues with not being able to power the unit. Trivial, I know, but you can never guess without trying it out
Ok, I will have to hunt down a 5 pin and 7 pin connector and flying leads. This might take some time as last time I looked they were not readily available locally. SE Australia.
Got you, thanks! Please keep us updated, then.
Polina, I have got hold of some 5 pin connectors and leads, no 7 pin yet.
I have just tried powering the old M2 from both the C1 and C2 ports using the same power supply as for previous tests. It boots perfectly from both.
So I guess I have a damaged S1 socket on the old M2 rather than the internal circuitry.
The cable I use to connect to the S1 will power my new M2 without any problems.
Coming back to my main concern going forwards with multiple future units, I think that I have probably damaged the S1 socket with multiple insertions of the connector over the last few years.
If that is the only likely reason then I am happy to put this one down to experience and move on.
Do you agree with my theory?
Yeah, your theory looks like the truth. As long as the unit powers up from other ports without any issues, it seems like only the thing can be the damaged S1 port socket. So I believe, if that suits you fine, you can just work with any other port available to power up your old M2 unit.