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raumzeitlabor / PiLight

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RpiDMX does odd things #2

Open Drachenkaetzchen opened 11 years ago

Drachenkaetzchen commented 11 years ago

I had a test-drive of the RpiDMX today, my setup was using the USB-TTL Converter which fits onto the pin headers. After starting it up (with the enable TX and set channel value commands), it works okay for some time, but suddenly stops transmitting. I was using the DMX lights at RaumZeitLabor with termination in place.

I'm not sure if this is a firmware issue or if the RpiDMX draws too much power for the USB-TTL-converter, but this definitely needs some investigation. Also, sometimes when submitting commands via:

echo -en '\x48\x2\x00'>/dev/ttyUSB0

Tthe command simply hangs, and I need to interrupt it with Ctrl+C, which returns an "interrupted system call" message. When it works okay, the echo returns immediately.

This was happening on both the Raspberry Pi and my laptop.

Drachenkaetzchen commented 11 years ago

It works without issues now, probably because the first Raspberry Pi I used could have a 100mA limit per USB port. The PiLight itself draws 104mA during operation, which might have been the cause. This excludes the USB-RS232 converter, for which the power draw is not known yet.

Older Raspberry Pis (Model B Rev A) definitely have that issue where they limit each port to 100mA. Probably the MAX481 would be an alternative, with 1.30€ for 100pcs. Leaving this issue open for discussion.