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raspberrypi / debugprobe

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USB Power Descriptor a little on the low side for -DDEBUG_ON_PICO=1? #148

Open peardox opened 3 weeks ago

peardox commented 3 weeks ago

In usb_descriptors.c the max power in ma is defined as 100ma via TUD_CONFIG_DESCRIPTOR(1, ITF_NUM_TOTAL, 0, CONFIG_TOTAL_LEN, 0, 100)

While this seems fine for the pre-built probe it does seem a little stingy if -DDEBUG_ON_PICO=1 as if for example you had a pico_w attached directly to a pico and sharing it's power it is quite easy to envisage transient larger power requirements

If a pico is switched to BOOTSEL then the USB descriptor rates it at 500ma - which seems a far more sensible value to use

lurch commented 3 weeks ago

I was wondering if powering 2 Picos from a single USB port is a recommended option, but then I found it explicitly mentioned in the getting-started-guide: Screenshot from 2024-08-22 14-37-47

peardox commented 3 weeks ago

I've been trying to do exactly as shown above and it ain't working - built many versions so was wondering if power was a problem The ready-buillt probe works fine but then you end up with a nasty spaghetti of USB cables Current plan is to have a probe attached to another device but nothing else