UIflow power functions Core INK

ajb2k3

It will fail if you removed the internal battery because the battery powers an RTC which is used for the sleep timer

Cognitive5525

Hello ajb2k3,
Thanks for your comment!

Yes, agree the RTC (BM8563) needs power during the sleep period.

Sorry but it seems I wasn't clear in my previous description: The tests described above are all done with battery power only. I feed the unit from an external battery through the BAT and GND pins via the female bus header at the underside of the CoreINK. And I do not remove the battery while the unit is sleeping - only between the tests.

What I did is:

Firmware latest UIflow. Load a simple MicroPython program that waits a bit and then calls power.restart_after_seconds(10)
disconnect USB while leaving external battery connected (BAT/GND) via amp-meter.
press reset button and then power on button
unit starts, waits and goes to sleep
unit wakes up after 10 sec waits a bit and goes to sleep again
let the unit loop through step 5 a few times. The amp meter (I-bat)shows less than 100 µA while sleeping and about 50 mA while running.
remove the battery and leave off for a while or short BAT/GND
reconnect battery
reset button and then power on button (same as step 3)
unit starts, waits and goes to sleep (program is the same)
unit never wakes up
try manual reset and power up (like step 3) a few times but unit is now unable to wake up after each time power.restart_after_seconds(10) is called.
connect USB and flash simple Arduino program that just calls M5.begin()
Run Arduino program one time
flash back UI firmware and load same MicroPython program as in step 1.
Continuing as from step 2
The unit is now able to wake-up again and keeps looping as before like in step 5

ajb2k3

Ahh I was assuming you were using a usb power bank and so the automatic shutdown was causing the problem.

Sound like the internal battery is not charging and so the BPS in cutting out which is used by the ULP and the RTC for the low power sleep. From your description it looks like it only works with external power which leads me to the conclusion Of the dead internal battery

Cognitive5525

Thanks for your comments.
As mentioned the internal battery is removed, but the external battery is fine and charging when the unit is connected to USB. I have a Amp-meter in the loop where I can monitor I_bat.

Let me try to explain in a different way:
The unit is connected to the external battery only (no USB ) and loaded with a UIflow-program that calls power.restart_after_seconds(n). Everything works as expected. The unit goes to sleep and wakes up after n seconds. I can reset and power down/up etc. etc. and it is still sleeping and waking up as expected - every time.

Then I disconnect the battery for a while for some reason - say to change the battery or simply because I don't need to use the unit for a while.

When I reconnect the battery and power up, everything still works except the wake-up. The unit goes to sleep but does not wake up after n seconds any more.

Erasing flash, reloading firmware and reloading the (same) program does not help - the only thing that helps so far is to flash and run M5.begin() from the Arduino C++ library and then flash back to the UIflow firmware.

I think there is some kind of setup for or in the RTC which is not truly persistent i.e. it relies on constant power from the battery and that the (re)initialization of this particular setup is missing or buggy in the Uiflow firmware.

ajb2k3

As I said, the battery 🪫 a used by the RTC and so removing the battery resets the RTC meaning you will need to reset the RTC every time yo reconnect power.
That’s why RTC modules normally have (and old computer bios’s ) have backup batteries to keep the RTC memory settings.

Cognitive5525

I fully agree with your last reply!

but to comment ".... you will need to reset the RTC every time yo reconnect power.":
I would be more than happy to do so in my program, but there seems to be no way to do it within the scope of the UIflow firmware - I can't find any power.rtc_init() function or what ever it could be called.
The only workaround (as far as I have found) is to use the Arduino C++ M5.begin() and then flash back the UIflow firmware

Anyone who replace the battery in their CoreINK risks "bricking" the low power sleep functionality unless they read this thread ;)

By the way, do you have any idea to what the power.on() function is for? It seems meaningless to be able to power on programmatically?

ajb2k3

There is a whole section for setting the RTC in UIFlow under the hardware section.

Cognitive5525

Yeah I have been looking there already and tried:

"dunder" init() (one is normally not supposed to run "dunder" functions)
set_datetime()
enable_timer_interrupt()

None of those helped.

Cognitive5525

Update: some further notes and a workaround solution.

I decided to dig a bit deeper into how the BM8563 RTC works and how it is initialized by the M5Stack Arduino C++ library. Without going into all the details I have so far found out the following:

Taking out the battery and leaving the CoreINK powerless does not in it self lead to the problem, as I have stated earlier in this thread. I seems the reason is some registers of the RTC sometimes become corrupted. Exactly how this happens, I'm not sure of, but one way may be when power (aka. the battery) is removed while data are written via I2C to the RTC. Important is however the matter of the fact: it can happen!

Apparently the the UIFlow firmware does not reset these registers correctly at start up. Digging into the Arduino library (which I knew could fix problem) I found the RTC init routine which resets the three control registers* of the BM8563. I then thought I could do the same with the I2C library in UIFlow. And sure enough, it works. So the workaround is to run the following code:

import i2c_bus

i2c0 = i2c_bus.easyI2C(i2c_bus.M_BUS, 0x51, freq=400000)
i2c0.write_u8(0x00, 0x00)
i2c0.write_u8(0x01, 0x00)
i2c0.write_u8(0x0D, 0x00)

some where in your script before the

m5stack.power.restart_after_seconds(n)

is called.

I haven't tested but I suppose it is the same if you use:

m5stack.power.restart_on(minutes=n, hours=n, date=n, weekday=n)

Notes to above code:
Please use the UIFlow I2C library (import i2c_bus) as the native Micropython I2C library (machine.I2C) messes up the "internal" I2C communication of the UIFlow firmware.
i2c_bus.M_BUS = (21,22) aka I2C pins for the BM8563 on the CoreINK
0x51 is the I2C address of the BM8563
0x00,0x01 and 0x0D are the control registers which are set to 0x00
The Arduino library for RTC init for comparison :

void RTC::begin(void) {
    Wire1.begin(21, 22);
    WriteReg(0x00, 0x00);
    WriteReg(0x01, 0x00);
    WriteReg(0x0D, 0x00);
}

*) please refer to the BM8563 datasheet for further details.

ajb2k3

@cognitive5525 there is a way to do this in UIFlow and I will look into it over the weekend. Thanks for finding the cause and a walk around

YusukeTaylor

@cognitive5525

Thank you for your insight and investigation.
I was facing same situation after my m5stack core2 lost its battery at all. Then I almost gave up development with m5stack since I'm not familiar to this ecosystem but it started restart again after your i2c cord had been tried.
Thank you so much again!!