Skip to main content
Associate III
April 22, 2026
Solved

Send command 0x7F with Teraterm while in bootloader mode

  • April 22, 2026
  • 1 reply
  • 190 views

hello ST Community,

I'm trying to send commands as indicated in the AN3155 manual via UART with Teraterm on the NUCLEO-H755ZI-Q for CM7.

system bootloader application note (AN3155) 

First, I tried establishing UART communication with the STM32CubeProgrammer, and it worked while Boot0 = 1 on the USART3 pins.

But I'd like to establish the same communication via UART using Teraterm serial. As soon as I set the bootloader state to Boot0 = 1, I send the command 0x7F, and I get no response on the terminal. What did I do wrong?

Thanks for supports

Best answer by mƎALLEm

@Domy_ST wrote:

hello @mƎALLEm ,

I suspect the send and receive encoding on Teraterm is set incorrectly.


That's indeed what I have a doubt in.. I'm not using TeraTerm.

Try Hercule. I didn't test that feature but you can have a try:

mALLEm_0-1776850499417.png

To send with HEX format:

mALLEm_0-1776852583118.png

 

1 reply

mƎALLEm
Technical Moderator
April 22, 2026

Hello,


@Domy_ST wrote:

I send the command 0x7F, and I get no response on the terminal. What did I do wrong?

Thanks for supports


How did you test that?

Probe USART3_Rx with an oscilloscope and check if you have the intended 0x7F received on that pin and what it was returned back on USART3_Tx..

"To give better visibility on the answered topics, please click on ""Accept as Solution"" on the reply which solved your issue or answered your question."
Domy_STAuthor
Associate III
April 22, 2026

hello @mƎALLEm ,

On the oscilloscope, I can see 0x7F for USART3_RX and various response values ​​for USART3_TX with STM32CubeProgrammer.

On the other hand, with Teraterm, I can see values ​​on both USART3_RX and USART3_TX, but not the values ​​I expect. I suspect the send and receive encoding on Teraterm is set incorrectly. Is there any serial software that correctly encodes the send and receive in HEX?

Thanks

 

mƎALLEm
mƎALLEmBest answer
Technical Moderator
April 22, 2026

@Domy_ST wrote:

hello @mƎALLEm ,

I suspect the send and receive encoding on Teraterm is set incorrectly.


That's indeed what I have a doubt in.. I'm not using TeraTerm.

Try Hercule. I didn't test that feature but you can have a try:

mALLEm_0-1776850499417.png

To send with HEX format:

mALLEm_0-1776852583118.png

 

"To give better visibility on the answered topics, please click on ""Accept as Solution"" on the reply which solved your issue or answered your question."