Tempo - an stm32 based temperature logger

[maor]

hey,
first serious post here,
glad to share my first hobbyist project, tempo.
enjoy.
https://youtu.be/xEt-9RTFhMY

[t1d]

Nice job.

[martinjaymckee]

Very well done on developing the Tempo.  The functionality you managed to fit into it seems very well thought out.  I especially liked the overview of the development process you gave.  It's important to for people to see how an idea evolves and grows.  You presented it very well.

Cheers,
Martin Jay McKee

[Rerouter]

In order to reduce power consumption further, I've many times pulled tricks like using an external SPI RTC to wake my device from power-down with a 1 second interrupt, this way everything is off until that pulse, and the RTC chews through less than 1uA to accomplish it.

Then my device wakes up, does all its magic in under 1ms, including writing to memory, then going back to sleep, and for sensors that have a longer conversion time, well that interrupt pulse has 2 edges, spaced 1/64 of a second after, So you set up your conversion, go to sleep, wake on the other edge of the interrupt and store the value before shutting things down for the rest of the second,

2mA idle current seems wrong, Is that the display chewing that??

[maor]

In order to reduce power consumption further, I've many times pulled tricks like using an external SPI RTC to wake my device from power-down with a 1 second interrupt, this way everything is off until that pulse, and the RTC chews through less than 1uA to accomplish it.

Then my device wakes up, does all its magic in under 1ms, including writing to memory, then going back to sleep, and for sensors that have a longer conversion time, well that interrupt pulse has 2 edges, spaced 1/64 of a second after, So you set up your conversion, go to sleep, wake on the other edge of the interrupt and store the value before shutting things down for the rest of the second,

2mA idle current seems wrong, Is that the display chewing that??

Hey,
The current is mostly pulled by the micro, I turn off the lcd when low power mode is on...
I might be able to reduce the  idle current even further.
I set a timer and put the micro in wait for interrupt mode (WFI) so that means I can turn off all of the APB clocks and lower the power even more.
I'll test that and get back to you.