Count deepsleep event? (without using flash)

[KenM]

Hi,

My device wakes up every few minutes from deepsleep checks a sensor and then goes back to deepsleep.

Now I want to send a lora message every hour about its status.
The problem is that I need some sense of relative past time after each wake up. (so I know it's time to send the update again)

I don't want to use flash since that would mean that the device writes every 1 or 2 minutes to that flash so I need some ram.
I only need a counter since I know it was sleeping for the time I set it, so every count is x minutes.

The ULP has ram that doesn't get erased during deepsleep, can I write and read 1 byte to it via python?

---

Current alternatives:
A solution I think of is that I change the year +1 for every wake-up and reset it when I reach the number of counts to send the lora message. (obviously having access to a byte from ULP would be much better)
Every 2 hour lora update and 1 minute sleep cycles means I have enough with a counter that goes up to 120, so even 7 bits is also ok.

Another solution is to send a message between minute 58 and 60 but then I will miss some messages or maybe have two. (so I don't want to do that)

Thanks

[jcaron]

@KenM You could also use the pycom.nvs_set and pycom.nvs_get methods.

Those write to flash, but use wear-levelling methods. The advantage is they'll survive more conditions than RTC.

[KenM]

Nevermind I figured it out:

import CountDeepSleep

print('Counting: ' + str(CountDeepSleep.NumberofDeepSleepWakeUps()))
if CountDeepSleep.RunSpecialEvent() :
    print ('Count reached')
else:
    machine.deepsleep(3000)

from machine import RTC
rtc = RTC()
ResetOnCount = 4 # constant value 

def StoreCount(NewCount):
    rtc.memory(str(NewCount)) # update RTC RAM memory
    WakeUps = NewCount

def ResetCount():
    rtc.memory('0')
    WakeUps = 0

def NumberofDeepSleepWakeUps():
    return WakeUps

def RunSpecialEvent():
    return WakeUps >= ResetOnCount

if rtc.memory().decode() == '' : # power on
    WakeUps = 1
else:
    WakeUps = int(rtc.memory()) + 1  # wake from deepsleep

if WakeUps >= ResetOnCount :
    rtc.memory('0')   # Reset, keep 'WakeUps' on the max value for this wake up
else:
    StoreCount(WakeUps) # update RTC RAM memory