[avrdude-dev] Problem with avr910

[Charles Steinkuehler]

I'm having problems with the avr910 programmer code in all recent 
versions of avrdude upto and including 4.3.0.  Avrdude is loosing sync 
with my programmer after sending a single-byte 'y' command to clear the LED.

I'm running on a windows system, and have tried both the windows 
installer and compiling from source under cygwin, with similar results, 
but I think the problem I'm having would affect the linux version, as well.

The problem looks like it stems from a bug in the original AVR app-note 
#910 code for the programmer chip.  The code for the 'x' and 'y' LED 
commands are documented to require an additional byte of data, but the 
provided .asm code only reads the initial command byte before returning 
#13, indicating the command compleated successfully.

I'm running boot-block code for in-system updates via the serial port 
based on the code from AVR-Freaks Design Note #32 (modifed to add the HW 
version command to make avrdude happy).  This code expects the 
documented second byte after an 'x' or 'y' LED command.

As a point of reference, the avrprog program from Atmel will happily 
talk to my boot-loader code as-is (2-byte LED commands and no hardware 
version command).  If I modify the 'y' command to return w/o expecting a 
second byte, avrdude will work, but avrprog throws a 'sync' error when 
programming.

This *shouldn't* even be an issue, as all the LED code in avr910.c is 
'no-ops'.  A bit of digging, however, turns up the avr910_write_setup 
procedure, which not only does a single-byte 'y' command, but includes a 
comment about cryptic programming problems:

<code>
/*
* For some reason, if we don't do this when writing to flash, the first 
byte
* of flash is not programmed. I susect that the board got out of sync after
* the erase and sending another command gets us back in sync. -TRoth
*/
static void avr910_write_setup(PROGRAMMER * pgm, AVRPART * p, AVRMEM * m)
{
 if (strcmp(m->desc, "flash") == 0) {
   avr910_send(pgm, "y", 1);
   avr910_vfy_cmd_sent(pgm, "clear LED");
 }
}
</code>

Pertinant verbose output from avrdude:
avrdude: reading input file 
"/cygdrive/c/Projects/Delphi/Hygrometer-App/Hygrometer-0103.hex"
avrdude: input file 
/cygdrive/c/Projects/Delphi/Hygrometer-App/Hygrometer-0103.hex auto 
detected as Intel Hex
avrdude: writing flash (7470 bytes):

Writing |                            | 0% 0.00savrdude:
Send: y [79]
avrdude: serial_recv(): programmer is not responding

--
Charles Steinkuehler

address@hidden