[avrdude-dev] Reset function for arduino

[Josef Wolf]

Hello,

The reset function for the arduino board seems not to be quite correct, IMHO.

The arduino_open() function, as implemented, leaves the *DTR and *RTS lines on
the TTL side in low level, causing the board to be in reset state permanently
if the board contains only the resistor without a capacitor (for example
arduino NG or Diecimila)

  http://arduino.cc/en/uploads/Main/arduino_NG_schematic.png
  http://arduino.cc/en/uploads/Main/Arduino-Diecimila-schematic.pdf

I would suggest to let the *RTS and *DTR lines go to high again after reset,
so the chip can actually run regardless whether there is a capacitor or a
resistor used to attach to the *RESET input.

The attached patch works for me with both types of boards, no matter whether a
resistor is used or a capacitor.

Opinions?

Index: arduino.c
===================================================================
--- arduino.c   (Revision 947)
+++ arduino.c   (Arbeitskopie)
@@ -92,8 +92,15 @@
    * (for example in Arduino) */
   serial_set_dtr_rts(&pgm->fd, 0);
   usleep(50*1000);
-  /* Set DTR and RTS back to high */
+
+  /* Set DTR and RTS back to high to assert RESET */
   serial_set_dtr_rts(&pgm->fd, 1);
+  usleep(5*1000);
+
+  /* Clear DTR and RTS again, so the chip can run even when a resistor is
+     used instead of a capacitor
+  */
+  serial_set_dtr_rts(&pgm->fd, 0);
   usleep(50*1000);

   /*