Optiboot ATmega328P- AU sync errror

I am working on a board that I have designed and put on an Atmeg328P-AU on it. I am running the Atmega at 3.3Volts and 8 Mhz resonator. I have been able to burn the 2k bootloader and download sketchs and they work. I download the optiboot for lilypad pro mini (3.3 V 8Mhz) w/atmega 328. The atmel takes the bootloader but I am then unable to download any sketches to it. I get a sync error. Help would be greatly appreciated.

dukeinaf:
I am working on a board that I have designed and put on an Atmeg328P-AU on it. I am running the Atmega at 3.3Volts and 8 Mhz resonator. I have been able to burn the 2k bootloader and download sketchs and they work. I download the optiboot for lilypad pro mini (3.3 V 8Mhz) w/atmega 328. The atmel takes the bootloader but I am then unable to download any sketches to it. I get a sync error. Help would be greatly appreciated.

Where did you locate this bootloader (Uno for a lilypad) ? Optiboot works at a faster serial baud rate then older 328 bootloaders and would require changes to the lily section of the boards.txt core file.

I got it from https://code.google.com/p/optiboot/. Should I use a different version of the optiboot?

dukeinaf:
I got it from Google Code Archive - Long-term storage for Google Code Project Hosting.. Should I use a different version of the optiboot?

Optiboot is designed to operate on 16Mhz 328 chips. It's not normally recommended to operate 328 chips at 16 MHz when powered with 3.3vdc. Not sure all you have to change for 8 MHz operation but the minimum is changing several values in the lily section of the core's board.txt files including baudrate, memory address range, fuse values. Maybe someone has done this already and can share. What is your main reasone for wanting to run optiboot on your lily pad?

Lefty

I am actually making my own board it is not a lily pad. I want to be able to have the smaller bootloader and more programming space. I thought Optiboot had a version that was for 3.3 volt and 8Mhz? I am wrong

dukeinaf:
I am actually making my own board it is not a lily pad. I want to be able to have the smaller bootloader and more programming space. I thought Optiboot had a version that was for 3.3 volt and 8Mhz? I am wrong

Lets see if anyone can answer that.

Burn the normal 328p 16MHz Bootloader, and change boards.txt to have an upload.speed of 57600 instead of 115200.
The optiboot source claims to build for some 8MHz systems at 115200, but I don't think that those versions actually work :frowning:
(building form the current source, you'd probably get significant warning messages:

 make lilypad
make atmega168 AVR_FREQ=8000000L LED_START_FLASHES=3
BAUD RATE CHECK: Desired: 115200, Real: 111111, UBRRL = 8, Error=3.5%
avr-gcc -g -Wall -Os -fno-inline-small-functions -fno-split-wide-types -mshort-calls -mmcu=atmega168 -DF_CPU=8000000L  -DBAUD_RATE=115200 -DLED_START_FLASHES=3        -c -o optiboot.o optiboot.c
optiboot.c:254:2: warning: #warning BAUD_RATE error greater than 2%