bugAVR Downloader/UploaDEr - Bugs: bug #55884, ft232r communication fails on...


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bug #55884: ft232r communication fails on programmed part if miso line toggles

Submitted by:  Klaus Syttkus <mumpel>
Submitted on:  Mon 11 Mar 2019 11:43:09 AM UTC  
Category:  None Severity:  3 - Normal
Priority:  5 - Normal Item Group:  None
Status:  None Privacy:  Public
Assigned to:  None Originator Name:  Klaus Syttkus
Open/Closed:  Open Release:  6.3
Programmer hardware:  ft232r Device type:  t85

Mon 11 Mar 2019 11:43:09 AM UTC, original submission:  

I use the miso line for UART emulation on my ATtiny, so that I can use the FT232R in ftdi_sio mode for communication.
In this configuration, reprogramming an ATtiny fails if the ATtiny produces continuous traffic right after RESET ("Device is not responding to program enable. Check connection").
This can be fixed by inserting a call to ft245r_drain in ft245r_program_enable:

--- /tmp/avrdude-6.3/ft245r.c   2014-09-15 21:01:09.000000000 +0200
+++ ft245r.c    2019-03-11 11:21:14.798593714 +0100
@@ -387,6 +387,7 @@
     avr_set_bits(p->op[AVR_OP_PGM_ENABLE], cmd);

     for(i = 0; i < 4; i++) {
+        ft245r_drain(pgm, 0);
         ft245r_cmd(pgm, cmd, res);

         if (res[p->pollindex-1] == p->pollvalue) return 0;

Klaus Syttkus <mumpel>


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