E.1 Classic parts

Classic devices may have the following memories in addition to eeprom, flash, signature and lock:

calibration

One or more bytes of RC oscillator calibration data

efuse

Extended fuse byte

fuse

Fuse byte in devices that have only a single fuse byte

hfuse

High fuse byte

lfuse

Low fuse byte

prodsig

Signature, calibration byte and serial number in a small read-only memory, which is only documented to be available for ATmega324PB, ATmega328PB, ATtiny102 and ATtiny104; AVRDUDE generally tries to make this memory available, also for parts where it is not documented, but not all programmers may be able to read this memory

sigrow

Memory alias for prodsig

sernum

The serial number part of prodsig; owing to scarce documentation this may not actually turn out to be a serial number or be readable by some programmers

usersig

Three extra flash pages for firmware settings; this memory is not erased during a chip erase. Only some classic parts, ATmega(64|128|256|644|1284|2564)RFR2, have a usersig memory. Usersig is different to flash in the sense that it can neither be accessed with ISP serial programming nor written to by bootloaders. AVRDUDE offers JTAG programming of classic-part usersig memories. As with all flash-type memories the -U option can only write 0-bits but not 1-bits. Hence, usersig needs to be erased before a file can be written to this memory region, e.g., using -T "erase usersig" -U usersig:w:parameters.hex:i

io

Volatile register memory; it cannot be accessed by external programming methods only by bootloaders, which has limited use unless the bootloader jumps to the application directly, i.e., without a WDT reset

sram

Volatile RAM memory; like io it cannot be accessed by external programming

This document was generated by Stefan Rueger on August 24, 2024 using texi2html 1.82.