Serial comms work but programming via FTDI doesn't

Forum 2005-2010 (read only) Hardware Interfacing
#1

Hi

I've built a custom board that has the standard 6-pin FTDI connector that I'm intending to use for serial comms to/from the board, and also updating the sketch as required in the future using a FTDI cable.

The setup connects the TX and RX pins from the FTDI to the RX and TX on the ATmega 328, and to this end the serial comms work fine. I can send and receive data back to my Mac no problem. However when I attempt to upload a new sketch to the board I get a timeout on the upload from the IDE.

What am I missing to have that work? The board itself is working fine (ie the current sketch on the 328 runs and does what it's intended to do).

The FTDI is wired thusly:

FTDI 6-Pin Connector from top of board: *-- RTS (GRN) --> GND *-- RX (YEL) --> TX *-- TX (ORG) --> RX *-- VCC (RED) --> VCC *-- CTS (BRN) --> GND *-- GND (BLK) --> GND

Any thoughts appreciated. I'm thinking I might need to do something with the RESET pin on the 328 other than simply wiring to 5V through a 10K pullup?

Cheers,

#2

Any thoughts appreciated. I'm thinking I might need to do something with the RESET pin on the 328 other than simply wiring to 5V through a 10K pullup?

Your correct, you are missing the auto-reset function where FTDI DTR signal is wired to a series .1ufd cap and then to the reset pin. I believe you can also use the RTS signal instead of the DTR signal if you wish. The Arduino IDE issues a DTR (and RTS) pulse to reset the board just prior to uploading to activate the bootloader code in the processor chip.

Lefty

#3

Cool, thanks - I figured it was something like that.

Cheers,

#4