Power-cycling reset vs JLink reset

RE: Power-cycling reset vs JLink reset

Sanjay Shreedharan — Sat, 18 Feb 2017 12:54:08 GMT

Re-initializing the MPU6050 seemed to solve the issue. Guess it is some issue with the SDK 4.4.2.

RE: Power-cycling reset vs JLink reset

Nicolas Tzovanis — Tue, 14 Feb 2017 23:07:23 GMT

Can you post the code you used to initialize the MPU-6050? I've had some issues before, when I was trying to initialize the MPU by reading the values of the registers and masking them before writing. Not sure if that's your case, but it's worth double-checking that.

RE: Power-cycling reset vs JLink reset

Sanjay Shreedharan — Sat, 11 Feb 2017 20:36:32 GMT

I am facing the same issue as above. I have a custom made board with nRF51822 QFAA, MPU6050 and CP2104 (USB to Serial converter). If I reset the board through JLink, I'm able to receive the accelerometer and gyroscope values through serial communication. If I hard reset the device, the accelerometer and gyroscope just gives me zeros.

I already tried the above solution and increased the initial delay to 10 seconds before MPU6050 is initialised. But even then, I get only zeros. Any help on this issue would be appreciated.

Thanks!

RE: Power-cycling reset vs JLink reset

Nicolas Tzovanis — Tue, 20 Oct 2015 12:21:37 GMT

Thanks Dave, that solved my problem! It wasn't mentioned in the documentation so it required some trial and error, but eventually it worked.

RE: Power-cycling reset vs JLink reset

Stefan Birnir Sverrisson — Wed, 14 Oct 2015 13:30:46 GMT

I have experienced that nRF51 can be powered through GPIO pins. I assume the MPU communicates with the nRF51 through SPI or TWI on configured GPIO pins. Somehow that MPU retains voltage on GPIO pins to power the nRF51 for a short while. That is what I can think of as a possible reason if the case is not what Dave points out.

RE: Power-cycling reset vs JLink reset

awneil — Wed, 14 Oct 2015 10:07:23 GMT

Fair point. (I guess the accelerometer counts as other "hardware things"...?)

RE: Power-cycling reset vs JLink reset

RK — Wed, 14 Oct 2015 08:14:11 GMT

His problem is the wrong way round for that. If it were the case the memory was not being reset when the power stayed on, then his JLink reset would fail, but the power-cycle one would work. His issue is the opposite to that, it works with JLink and fails when he power-cycles it. I think it's more likely to be what Dave mentions above, the accelerometer IS set up, however it's set up too early.

RE: Power-cycling reset vs JLink reset

awneil — Wed, 14 Oct 2015 08:08:31 GMT

Yes - the big difference between a power-cycle and a jLink (or other) reset is that the power remains connected during the reset. So there are going to be hardware things that are not affected - in particular, memory contents.

So the first thing to check would be that you're not relying upon any uninitialised variables or memory areas...

RE: Power-cycling reset vs JLink reset

RK — Wed, 14 Oct 2015 03:04:58 GMT

There are differences between a power-down reset and a jLink reset, but not many. Both of them restart the code at the reset_handler and if your variable is correctly a static variable with default zero it will be in the BSS section and it will be initialised to zero in both cases.

So it's unlikely that's your problem.

RE: Power-cycling reset vs JLink reset

Dave_couling — Tue, 13 Oct 2015 19:51:18 GMT

Often time with accelerometers there are required delays after a Power-cycle before you can safely write to their registers them. This is because there are internal sub-routines that occur. I've interfaced to several difference sensors which all had their own required delay after a POR. On a Reset-pin Reset this delay isn't required. Something to look into.