Arduino Forum

Topics => Product Design => Topic started by: adrianpang on Jun 10, 2014, 08:29 am

Title: Use TXLED, RXLED and HWB pins as GPIO
Post by: adrianpang on Jun 10, 2014, 08:29 am
I have a prototype board based on Leonardo and have burnt the bootloader onto the ATmega32U4 IC. I need to use TXLED, RXLED and HWB as general purpose I/O.

What is the best way to do so without replacing the bootloader with something customised?
Title: Re: Use TXLED, RXLED and HWB pins as GPIO
Post by: adrianpang on Jul 04, 2014, 05:03 pm
What do I need to modify in the bootloader to make TXLED, RXLED and HWB pins function as GPIO?
Title: Re: Use TXLED, RXLED and HWB pins as GPIO
Post by: CrossRoads on Jul 04, 2014, 08:03 pm
Likely need to change pins_arduino.h for that board.
"HWB allows to execute the bootloader section after reset when tied to ground during external
reset pulse. The HWB mode of this pin is active only when the HWBE fuse is enable. During normal
operation (excluded Reset), this pin acts as a general purpose I/O."
So a fuse setting change might be needed in boards.txt as well.
The 32U4 is a little different in that is has USB functionality built in as well, so you'll want to investigate further before changing that fuse.