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Re: [avrdude-dev] new USB-based programmer with Igor USB
From: |
Jan-Hinnerk Reichert |
Subject: |
Re: [avrdude-dev] new USB-based programmer with Igor USB |
Date: |
Thu, 27 Nov 2003 04:43:10 +0100 |
User-agent: |
KMail/1.5.1 |
On Wednesday 26 November 2003 23:50, Jeff Epler wrote:
> On Tue, Nov 25, 2003 at 08:17:28AM -0600, Jeff Epler wrote:
> > Because "it could be done", I tried out the avr-based USB device
> > code written by Igor Cesko, and quickly had a very versatile,
> > USB-controlled device. (http://www.cesko.host.sk)
>
> [...]
>
> I've improved things further with related changes to the USB
> firmware and avrdude. By cutting as many corners as possible,
> including using timings that I only know are safe due to the long
> packet times of USB compared to the times in the data sheets
> (tWD_PROG, etc), I am able to program at about 100 bytes per
> second. The 270-byte program I mentioned earlier takes 3 seconds
> to erase + program + verify, and a 2k firmware takes 16 seconds.
> Verify accounts for fully half that time, so it takes 7 seconds to
> erase + program a 2k firmware.
It just came back to my mind, that there seems to be a much better
solution to programming via USB.
The new revisions of the USB-chips from FTDI have a bit-banging mode.
These chips do pretty much everything one can dream of ;-)
- full-speed USB
- level-shifters at the I/O (3.0-5.0V)
- driver for linux at http://ftdi-usb-sio.sourceforge.net/
- bit-bang mode
Take a look at http://www.ftdichip.com and especially at
http://www.ftdichip.com/Documents/AN232-01_BitBang.pdf
The bit-bang mode sounds real cool:
You set a data-direction-register and program the clock rate at which
data should be set/read.
Then you sent a packet of data and it gets latched out at the
specified rate (as long as there is something left in the buffer).
However, the application note is a bit unspecific about read back
(e.g. it does not tell if readback goes on when there is no data to
shift out)
And now the usual disclaimer: I am in no way affiliated with FTDI Ltd.
/Jan-Hinnerk