Hello,
I mounted 2 ESC V3 boards with components.
I'm trying to program the Atmega with the software ESC_BEMF_V3_CODE_V4_1 (made by Electronoobs).
The programming failed each time.
I'm using Arduino IDE v1.8.13 to program with the following configuration parameters : Atmega328P 5V 16MHz, programmer AVRISP MkII.
I'm also using the USB to serial converter FT232RL FTDI Basic USB 3.3V 5V TTL. This converter is connected to the 5 pins (GND, VCC, RX, TX and DTR) of the ESC board.
It seems that the Atmega is not reset when I start the upload.
Any idea why I cannot program? Do I use the correct programmer under Arduino IDE? Is there another way to upload?
Thanks for your help.
Pascal

Well, it could be the DTR capacitor, that's in charge of the reset when uplaoding. That must be 100nF. As you can see here: https://electronoobs.com/images/Arduino/tut_91/sch_1.jpg C6 is of 100nF and it must be a good capacitor. If that's not the problem, maybe some of the pins are not connected well...

Hello,

I used a tool to spy the following signals between the FTDI and the ESC:
Channel 0 : DTR
Channel 1 : +5V
Channel 2 : TX of FTDI
I attached a screen copy of this spy.
As you can see, the DTR is always low.
We can see that some bytes are transmitted on the TX. 3 times at the beginning of the upload, and then 1 bytes every 10s.
To try to program, I use the Arduino IDE configured as follow : processor = Atmega328P 5V 16MHz, programmer = USBAsp
Any idea why the DTR stays low ?

Here after is the capture of the first byte sent by the FTDI.

Here after is a capture of a successfull upload to an Arduino Pro mini.
Channel 0 : DTR
Channel 1 : +5V
Channel 2 : TX from FTDI
Channel 3 : RX from FTDI

Here after is a capture of aborted upload to ESC V3
Channel 0 : DTR
Channel 1 : +5V
Channel 2 : TX from FTDI
Channel 3 : RX from FTDI
Channel 4 : TX from Atmega328P capture at pin 31 of Atmega
Do you find normal that the TX (channel 4) is most of time set to 0? Should it be 1 most of the time ?

Here after is a zoom on the previous capture. I zoomed on the first byte transmitted by the FTDI.
We can see that the channel 3 (RX FTDI) and channel 4 (TX of Atmega328P) are equal, which is normal.

Here after is a capture of :
Channel 0 : DTR
Channel 1 : +5V
Channel 2 : TX from FTDI
Channel 3 : RX from FTDI
Channel 4 : RESET pin of Atmega328P
The time of RESET low is around 323µs.
The RESET signal is not clean. There are rebound at the end of RESET, just before RESET going high permanently.
Any idea ?

I think the programmer should be AVRISP mkii