gnupic: Re: [gnupic] Follow-up question to the thread about Ben's port of Brad's Lab2 to gpasm
Subject:
Re: [gnupic] Follow-up question to the thread about Ben's port of
Brad's Lab2 to gpasm
From:
Ben Dugan ####@####.####
Date:
2 Jan 2006 14:23:22 +0000
Message-Id: <43B93751.5010304@curdes.com>
Nick,
> I'm using an 18f2455 so I took Brad's lab2.asm code and made the minimal
> changes to make it assemble/link with Ben's ported macro file because Ben's
> version uses a 4455 with PORTD's, etc.
That's sensible.
> It's built into a homebrew (very minimal) circuit that seems to work to some
> extent - I can write programmes that will blink leds at more or less the
> intended frequency!!! I've got a 4MHz crystal strapped across OSC1 and OSC2
> with 22pf ceramic capacitors from each pin to ground. I've changed the config
> fuse settings to INTOSC_XT.
>
> On running the firmware, the RA0 status led to come on, but the device isn't
> being recognised by the Linux box and obviously the host app code doesn't
> find a matching device.
>
> I'm guessing that I've made some mistake either with the crystal hardware or
> the config fuses - or knowing me, both!
My guess is that one of the config fuse settings isn't right. I would
check the ones relating to USB clock generation especially. Since your
hardware is more like Brad's than mine, his fuse settings are probably a
better starting point than mine.
I assume lsusb is showing nothing for this device; is that right? You
might learn something from dmesg, too; it will show linux attempting to
handle the device if its getting anything at all from it. When I was
recently debugging a device, for instance, it showed me that it was
trying to handle a low speed device and then gave up. This was useful
information because I new the device should be a full-speed one which,
in turn, led me to find that I'd swapped the D+ and D- lines in hardware
(so the pull-up was on the wrong line).
If you get any more clues, pass them along and I'll see if I can think
of any suggestions.
Ben
