Oak Reset errrr not resetting

[Nevyn]

I'm working on a project where I want to have the Oak wake up, record some data and send to the Internet and then go to sleep again for a predefined period.  Then rinse and repeat as they say.

So I have a DS3234 RTC providing the alarm signal.  This provides a low signal (not pulse) when a predefined time has been reached.

The DS3234 is connected to another microcontroller (STM8S) that takes the low signal and generates a 300us low pulse.  This pulse is connected to the reset pin on the Oak.

As a test I have set the Oak to work on a 2 minute period and everything works for a while.  The pulse is 300us long, I've checked this on the scope.  The reset happens every 2 minutes on the top of the minute.  The Oak enters a permanent loop toggling the onboard LED to show it is working while it is waiting for the reset signal.

However, this is not reliable.  After a short while (the time period varies) the Oak stops resetting.  In fact it becomes unresponsive.

At first I though this might be a problem with the reset pulse not getting through.  The circuit is on protoboard after all so there could be an issue with that.  I have tried to reset using a switch on the board connected to the reset pin and even this fails.

The only way I can get the Oak running again is to toggle the power to the circuit.

Any pointers on how I can resolve this would be much appreciated.

Regards,
Mark

[exeng]

This will not add much to the discussion  but I have had Oaks fail the reset (actually not wakeup) that have been operating for days or weeks without  any problems using deep sleep.  RST is connected to WAKE. No external triggers used. It happens  so infrequently  that I haven't tried to figure out what would cause it. Just chalked it up to reset not getting done for whatever reason and then never occurring  again, powered on but not functioning. Power off then on will bring it back. So.... would be very interested in what you find.

[Nevyn]

I've also found that the power on always works.  I'm heading towards powering the Oak on/off using a transistor rather than resetting the Oak.

Regards,
Mark

[PeterF]

This will not add much to the discussion  but I have had Oaks fail the reset (actually not wakeup) that have been operating for days or weeks without  any problems using deep sleep.  RST is connected to WAKE. No external triggers used. It happens  so infrequently  that I haven't tried to figure out what would cause it. Just chalked it up to reset not getting done for whatever reason and then never occurring  again, powered on but not functioning. Power off then on will bring it back. So.... would be very interested in what you find.

Don't say that... you'll jinx my two Oaks!!! I've had two running 1.0.1 for a few weeks now (with deep sleep resets) and they have yet to croak... And a third is running a TFT display 24x7 and is also stable... as long as I don't want to load another program on... then it's program via safe mode, but that is the only issue there. Two are running from USB power (sensor and display units) and the third (sensor) is running from a solar charged lipo.

So I can't say (yet) that I have had this issue! 

[Nevyn]

I was wondering about dropping back to 1.0.1 (I'm running 1.0.2) to see if that makes a difference.

I'm not using the Oak sleep and wake functionality, I'm using an external reset line from an STM8S.  The signal looks reasonable on the scope.  Drops to a few millivolts, not spot on ground but close.  Pulse looks to be wide enough, I believe that 100us is the minimum, I went for 300us to be on the safe side.  The Oak sends the usual garbage characters to the serial port so I think it has at least started the reset process.  It just gets to a point where it occasionally just hangs just after the garbage appears on the serial stream.

Regards,
Mark