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Re: [avrdude-dev] half-duplex
From: |
Axelrod, Ben |
Subject: |
Re: [avrdude-dev] half-duplex |
Date: |
Tue, 10 Jun 2014 14:11:54 +0000 |
After a little bit of poking around in the avrdude source code, I think the
best course of action would be to make a new programmer type. I'd basically
just clone butterfly (because it implements the protocol I need), but replace
the serial reads and writes with the ftdi library versions. And wrap the
writes in the ftdi command to pull the RTS pin high (due to my half-duplex
link). How does that sound?
My understanding of the AVR109 protocol is that only one device is talking at
any given time, so it should work over a half-duplex link. Although I haven't
verified this yet.
Thanks,
Ben
-----Original Message-----
From: address@hidden [mailto:address@hidden On Behalf Of Axelrod, Ben
Sent: Friday, June 06, 2014 4:29 PM
To: 'address@hidden'
Subject: [avrdude-dev] half-duplex
I would like to use avrdude to program my chip through the xboot bootlader,
over a ftdi cable
(http://www.ftdichip.com/Support/Documents/DataSheets/Cables/DS_USB_RS232_CABLES.pdf)
and a half-duplex communication bus. Is this possible?
I think the tricky part is the half-duplex bus. This means that avrdude will
need to pull the transceiver-enable line high (the RTS line) while
transmitting, then low when waiting for a response. My version of xboot is
hacked to have this feature. (FYI I have used avrdude + xboot in the past, but
was either going through the avrispmkII, or going straight through the serial
port on a gumstix using the AVR109 "programmer").
Is this half-duplex programmer-less option supported in avrdude? Or would it
be easy (for me) to add? I poked around a little and it looks like the ftdi
library does support low-level control of this pin. Although I haven't tried
it yet.
My only other option is to use a secondary chip to be some sort of go-between.
(full-duplex on one side, and half on the other). But this would have to know
when each side is done talking to appropriately switch the transceiver enable
pin...
Thanks,
Ben
Ben Axelrod
Sr. Robotics Software Engineer
iRobot Corporation
8 Crosby Drive, M/S 8-1
Bedford, MA 01730
(781) 430-3315
address@hidden<mailto:address@hidden>
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