Deep Sleep

profezzorn · August 10, 2025, 11:08pm

It depends a bit on what components are used and how they are wired.
I think right now most proffieboards draw about ~1mA in standby.

Assuming a 3000mAh battery, this is 3000 hours, or ~125 days. Decent, but not fantastic.

There is an #if 0 in the code here:

github.com

profezzorn/ProffieOS/blob/be5ffdb77ccb3981e1093cc5856df84b9b2dbee9/common/clock_control.h#L31


      
          #endif
                ) {
                last_activity_ = millis();
              }
              // These two variables must be read in order.
              uint32_t last_activity = last_activity_;
              uint32_t now = millis();
              if (now - last_activity > 30000) {
                uint32_t pclk1 = stm32l4_system_pclk1();
                uint32_t pclk2 = stm32l4_system_pclk2();
          #if 0 // #ifdef PROFFIEBOARD_VERSION
                // This saves power, but also casuses freezing.
                // TODO: FIgure out why and re-enable.
                stm32l4_system_sysclk_configure(1000000, 500000, 500000);
          #else
                stm32l4_system_sysclk_configure(16000000, 8000000, 8000000);
          #endif
          #ifdef COMMON_I2CBUS_H
                // Motion and other things might still be going on.
                if (i2cbus.used())
                  delay(5);

Changing this to #if 1 makes the proffieboard draw ~0.65mA in standby, which would give you ~192 days. However, it causes crashes, which is why it’s not on at this time.

In theory, deep sleep should push this down to ~0.1mA (~3 years), but in practice, I have not been able to get this to work yet. Once I shut of the CPU, something odd happens and the SD card starts to draw more power than it should.

Note that most li-ion batteries will self-discharge faster than 0.1mA, so at that point it’s all up to how good a battery you have…

dg4prez · August 11, 2025, 12:25am

I don’t speak for everyone but I would be super satisfied with 125 days. Would an infinity standby be nice? Yes. But 1/3 of a year would be quite satisfactory.