Nucleo-H745ZI - USART via ST-LINK

[MEde.1]

Using a Nucleo-H745ZI, board revision D-01.

According to rev. 5 of UM2408 "User Manual STM32H7 Nucleo-144 boards (MB1363)"

USART3 is available via ST_Link. Table 12 lists the config for the virtual com port as the default config

However, my board had SB103 and SB104 already in place (for clarity SB16 and SB17 also on). I have a very basic program to print via the uart (it works fine on an L476RG) and I have configured USART3 on each of the alternate pins in turn. I have also removed SB103 and SB104 as per the table above and still nothing works.

I see the virtual com port in the device manager under windows.

I can write to the board and run LED blinking programs on the two cores, independently and at the same time.

I have spent days on this and have pretty much run out of documented options, can anyone offer other things to try (I have a new board arriving in a couple of days in case this is broken) 

EDITED: To improve clarity

[TDK]

Should work. Make sure PD8/PD9 are assigned to a core. If you have a scope or logic analyzer, check for the signal. Make sure baud rate and other settings are compatible on your terminal program. Step through sending code and ensure everything is working as correct and HAL_OK is returned when appropriate. Note that STM32L4 programs may not run on an STM32H7 without modification.

The state of SB103/SB104 doesn't matter here, only SB16/SB17 need to be connected. You can see the schematic in CAD Resource in the product page.

[SofLit · Accepted solution]

Hello @MEde.1 

Attached a project which I print an incremented value via HyperTerminal over UART3.

Please test it. If it doesn't work please double check your HW.

[MEde.1]

Thank you, that is working. I will critically compare your code to mine.

Knowing everything is working as it should is a great relief, I just need to figure out what I was doing wrong 🙂

I really appreciate you taking the time to do the sample project for me.