Hi,
if I was trying to do this with a DYI solution while aiming for single
USB connection, I'd have a look at something based on FT2232H from FTDI.
Dual channel serial device, in UART mode by default but can switch
(among others) to SPI which is used by both ATMEGA128A and ATMEGA2560
for program memory programming.
If I am not mistaken, both of those chips could also be powered from
3.3V output of the FTDI - albeit not with highest clock with the 2560.
Avrdude on the PC side for uploading the program.
I am not familiar with any AVR boards except for their name in NuttX
configuration so can't tell you if there is a solution the can be bought
and used out-of-the-box.
As for what is the most popular chip for use in NuttX - no idea. The
arduino-mega2560 was chosen to be covered by MemBrowse Memory Report but
IDK what was the reason to pick that board specifically. There is pretty
much no development activity in arch/avr so can't judge much from that
either. If someone wanted me to recommend AVR chip for new design, I
would certainly recommend the new generation (AVR128DA28 etc.) but
support for that family was added last year so there is little chance
that it is the most popular one.
I believe Alan was trying to run NuttX on one of the older supported
chips last year but as far as I know, could not make it work. Don't
remember which chip was that though.
Btw. if I remember correctly, the AtMega256 has a bug in NuttX - one of
the I/O registers that facilitates access to program memory addresses
higher than 16 bits is not stored in process context. The other chips
with 128kB of flash are not affected. So I would probably not use that
one for any tests that are designed to try to break things.
On 2026-10-03 11:37, Tomek CEDRO wrote:
Hello world :-)
I am looking for hints on how to quickly connect AVR device over
single USB connection to have flash and shell connectivity to my test
suite.
I have several bigger devices but only as cpu module bare bones on a
pcb so no interfacing even no power supply: ATMEGA128A and
ATMEGA2560.
Which AVR devices are most popular on NuttX? If not 128 or 2560 but
some inexpensive board with flash+shell link onboard then I will get
one please let me know :-)
Any hints welcome :-)
Tomek
--
CeDeROM, SQ7MHZ, http://www.tomek.cedro.info
