Hardware test point

Hardware, PWM, and Optics
1

I’m playing with some hardware and also trying to look at this issue: Frequency Setting off target · Issue #5 · Pioreactor/rpi_hardware_pwm · GitHub

Is there a test point on the HAT? What ground are the PWM outputs tied to?

Also, I was wondering if the PCB design files are available anywhere. I didn’t see a repo immediately but thought I would ask. Just idle curiosity, no real plans to do anything with them.

2

Hi @chri-s,

By default, the PWM pins are tied to the same 5V rail and GND as the Raspberry Pi. The PWM outputs are controlled by PWMing a specific GPIO pin. The PWM ↔ GPIO mapping is:

 { 
    "1": 17,
    "2": 13,  # hardware PWM1 available
    "3": 16,
    "4": 12,  # hardware PWM0 available
}

For that issue, you could look at PWM 2 and 4, then.

Note: I haven’t given that issue much attention, because the Pioreactor (so far) hasn’t cared about specific frequencies. The pumps/fans/etc work well enough at 200 hz as they do at 200.1 hz. So I’ve back-burned that issue.

PCB design files will be coming out as we start to open-source the Pioreactor! PCB will be the last part open sourced, but I expect by EOY.

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