STOP mode on CH32V203 ??

[fulda1]

Hi All,

playing with one device, that have 2 power sources -> grid and battery. Pin PA0 indicate the source. PA0=1 means grid, PA0=0 means battery.
This one device is requested to sleep on battery mode with minimal consumption.

I expect following code will do all I need:

void PinUp() {} // empty function....

// .... in main, detected PA0 is low....
  attachInterrupt(PA0, GPIO_Mode_IN_FLOATING,  &PinUp, EXTI_Mode_Interrupt, EXTI_Trigger_Rising);
  PWR_EnterSTOPMode(PWR_Regulator_ON, PWR_STOPEntry_WFI);
  detachInterrupt(PA0);

unfortunately it freeze and newer wake up :(

[fulda1]

OK, found my problem. The problem is not in sleep itself, but in USART2. It somehow stops receiving data / or producing interrupt when receive. It means, I must check whet happens and how to put usart to sleep.

[fulda1]

OK, spent all day searching for problem, why my device changed behavior. and found it!!!

I realized, that entering sleep mode (for example wfi instruction) change system clock from PLL clock used by arduino_core to HSI clock (8MHz). (mentioned in datasheet as: "Note: This bit is cleared by hardware when entering stop or standby low-power mode.")

Of course, some peripherals are more sensitive for having clock 6 to 18 times slower (depend on your board setting).

Easy solution is, re-initialize system clock by calling SystemInit();. It means, final code must be:

void PinUp() {} // empty function....

// .... in main, detected PA0 is low....
  attachInterrupt(PA0, GPIO_Mode_IN_FLOATING,  &PinUp, EXTI_Mode_Interrupt, EXTI_Trigger_Rising);
  PWR_EnterSTOPMode(PWR_Regulator_ON, PWR_STOPEntry_WFI);
  SystemInit();
  detachInterrupt(PA0);

The question is, if it should be on user, or part of PWR_EnterSTOPMode ??

Will keep this issue open for some time, to receive community feedback.

[maxint-rd]

Great to see you're diving into this. Some details are seemingly hidden away in a single sentence comment in the datasheet. Good find!

Last year I dug a little bit into sleep mode on the V003, but didn't get very deep. (Had a first go at making parts of the Adafruit SleepyDog library compatible with V003). My knowledge in that area still has many gaps. Switching peripherals and i/o ports off and on is one of those gaps.

Recently I put a V203 TSSOP20 on breadboard to test my V00x fix for the Adafruit Neopixel library. I did notice some interesting differences with regards to NOP processing times. Unfortunately I don't have enough spare time to join your efforts now, but if you have any ready to run example code you'd like me to test, feel free to post it here. (My multimeter is probably a bit too cheap to do any serious power usage measurements).

Wish you all the best in getting the most out of your V203. Thank you for your contributions to our (perhaps tiny) community!