Dear followers,
thanks for being interested in this project! Unfortunately, I do not have not had much time to work on it. As mentioned in the status, the heating is causing some headache. These are some observations:
- It seems one needs to be very careful switching the CPUs on. Initially, I had foreseen a reed-relay for this. Too crude, I fear. When turning on, some CPU starts to heat up quickly, while others do not. The one getting hot changes with power cycle.
- Switching on the CPUs too sudden also caused a break down of board voltage, which caused the USB connection to become unstable.
- I could not find sockets for the CPUs and soldered them directly on the PCB, which makes troubleshooting now quite difficult. Moreover they are powered in parallel. I have the suspicion that some CPU is broken.
- Software USB and one-wire does not go well together. I have not figured out a solid way to make this stable. Either USB interrupts the one wire timing, or - with USB interrupts disabled during one wire transactions - USB becomes unstable.
Summary: while temperature monitoring and LED blinking works like a charm, powering the CPUs was so far not successful in a reproducible manner and I could not verify that the idea of periodically triggering the self-test would really work.
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