use upstream stm32f4xx-hal
Awaiting PR approval https://github.com/stm32-rs/stm32f4xx-hal/pull/239 , just awaiting the maintainers to approve the PR it seems.
main.rs refactor to reduce length
test Zotino DAC temperature stabilization
Here's stability over a period of 5 minuites. Result looks reasonable given there's barely any insulation on the zotino.
test Zotino DAC temperature stabilization
Tested the limits of the Zotino cooling. Even with very good airflow, the TEC can only reach 17.5 deg C with an ambient temperature of 27 deg C. Further lowering the temperature will require larger…