Avrdude fails to verify after upload

Question

I'm using the most recent Arduino IDE to upload a sketch to an Arduino Uno, and the upload seems to succeed, but the final verification step fails with the error:

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.00s

avrdude: Device signature = 0x1e950f
avrdude: reading input file ".build_ano/uno/firmware.hex"
avrdude: writing flash (30908 bytes):

Writing | ################################################## | 100% 5.01s

avrdude: 30908 bytes of flash written
avrdude: verifying flash memory against .build_ano/uno/firmware.hex:
avrdude: load data flash data from input file .build_ano/uno/firmware.hex:
avrdude: input file .build_ano/uno/firmware.hex contains 30908 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 3.96s

avrdude: verifying ...
avrdude: verification error, first mismatch at byte 0x7800
         0xff != 0xfe
avrdude: verification error; content mismatch

avrdude: safemode: Fuses OK (H:00, E:00, L:00)

avrdude done.  Thank you.

I've re-ran the upload several times, and tried different USB cables, but I get the exact same verification error each time. Does this mean the upload effectively failed (presumably because the flash memory has gone bad), and that my sketch is not running on the Arduino? Is there any way I can fix this?

I tried uploading to a different Arduino Uno, and I received the exact same error.

Answer 1

So here is my official answer ;-)

Your sketch goes above the 30k flash available on the Arduino Uno.

Yes the Uno has 32k of flash, but 2k is used for the Arduino bootloader. if you convert 0x7800 in decimal that gives you 30720 which is exactly 30k. And your sketch is 30908 bytes so it's 188 bytes too long.

Try optimizing it.

A second alternative would be to use the Optiboot bootloader replacement (https://github.com/Optiboot/optiboot) which only uses 512 bytes.