Is there a reason a MightHat mote won't hold its sketch through a power outage?

[HeneryH]

If I leave my MightyHat/Pi unplugged for a few minutes, my Mote doesn't retain its sketch and needs to be reflashed.
Ideas?

Here is a video.  Thirty second outage and the Mote loses its image.

https://youtu.be/NO5uJURT1bE

[Felix]

1) Are you running the default sketch? Any special mods to that?

2) How do you power the whole setup?
Is it my impression or do I see 2 USB connectors (one to MHat, one to Pi)?

Anyway, unplugging power with no battery attached - everything powers down, as expected, regardless if it's 1 second or 30.
When you reapply power, MHat becomes active, then you can start powering the Pi again etc.

3) You specifically mention 30 seconds  and you count it out loud in the video - is that because this does not happen for less time?

x) you then proceed to attaching FTDI - this is sort of OK - if the Pi is OFF (no interference from Pi's serial) and the GROUNDs are the same.

[HeneryH]

Total default sketch except for network ID.

That is a USB power cable into the Hat.   The other cable is an HDMI cable out to a display.

I'd expect everything to power down when power is turned off, but wasn't expecting the sketch to get erased.

The sketch stayed put for a 5-sec power loss, lost for a 30-sec loss.  Didn't test the delays in between.

I'll be more careful about only one ground.

[Felix]

The sketch being erased - that I could hardly believe until I read the atmega flash with an ISP programmer, and compare.
Or something very wrong is going on, nobody ever reported anything like this.
I don't know what to guesstimate could be happening next...

Can you try this without the Pi (just the MHat)?

[HeneryH]

Hmmm.

At the point I "thought" it needed a reflash, just a reset fixed it.  Pretty reliable behavior.

I'll try it standalone and see if maybe the HDMI or something else might be impacting it.

[HeneryH]

Tested with the Pi/Hat isolated with just a single power port connection.

Same behavior.  Needs a reset button press to get it to come alive.

I'll try just the Hat alone...

[HeneryH]

Even just the Hat standalone exhibits the same behavior.  Requires a reset button press after powering up.

I'll need to find a fix for this since it will need to recover well after a power cycle as this unit will be remote without user access.

[Felix]

Ok let's keep the conversation open as you make any progress.
I have to find some time to test a MHat for this behavior, and if it's a fault, it has to be fixed.

BTW - will you not use a battery with this MHat?
That would keep it going, until the battery lasts (low battery shutdown), or power comes back. That's the only way I've been using (and intended) the Mhat.
Either way it should come back and run the code after a power fail.

[HeneryH]

I have been using it primarily just for the Mot/LCD/Power interfaces to the Pi.

I have a spare LiPo that I can use though.  That would be a quick fix. Good idea.

I have an older Hat on my 433 system that I don't think behaved in the same manner.  Could be a an edge case with the power-up cycle that causes it to not boot properly.

[Felix]

I will investigate on my end. Let me know if you find anything else.

[HeneryH]

Is there any way for me to reset the Moteino on the MH remotely from the Pi?

While the battery helps with short term power outages, being a remote system, I want to think ahead to how I can reset the Mot on the MH remotely if the battery ever runs down.

I'll look at the schematic and see if there is any way for me to tie a GPIO pin to the reset.

[Felix]

Yup you can do that easily through Pi pin 22, there is a solder jumper above the Pi header on the MightyHat.

[HeneryH]

Nice, thanks.



Has anyone else ever seen the behavior shown in the video above where you need to reset the Mote after a power-up?

[thep33t]

I was just starting to analyze this exact issue. R3 - Pi3 - standard Sketch. Either the reset switch, or flipping the battery switch off/on again w/o battery attached will cause the reboot and then the LCD to print data. However, the sketch is still running on initial cold-boot, even without anything on the LCD (Backlight works, but the output is missing.)

I imagine is is with the sketch itself, and that will be the first thing I tinker with to find out what is happening.

[thep33t]

Did some more debugging.
1) It is not the sketch, I tried changing the sketch as  as well as simply writing to the LCD without the U8G library.
2) I tried a fake 'reset', by jumping to program position zero, as well as invoking a watchdog restart. Neither worked.
3) The LCD seems to require a hard reset in order to start functioning.


For now, I will either run without LCD, or incorporate a PI reset of the MOTE if I need the LCD.

Code Select Expand

import RPi.GPIO as GPIO
import time

time.sleep(2)
GPIO.setmode(GPIO.BOARD)

GPIO.setup(22, GPIO.OUT)

GPIO.output(22, True)
time.sleep(2)
GPIO.output(22,False)
time.sleep(2)
GPIO.output(22, True)