Is the UART6 Clock enabled? Did you configure the GPIO pins for UART6 operation? On the Nucleo-H753ZI board, UART6 TX/RX is probably on PD8/PD9. UART6 is an alternate function of those pins. ________________________________ From: Ludovic Vanasse <lvana...@luxaerobot.com> Sent: Tuesday, August 12, 2025 11:33 AM To: dev@nuttx.apache.org <dev@nuttx.apache.org> Subject: Port of Nucleo-H7543ZI - Issue with UART6
Hi everybody, I'm working on porting NuttX to the Nucelo-H753ZI and basing it on the Nucelo-H743ZI. It's going pretty well. But now I feel like I've hit a wall, and I am coming here to see if anybody has an idea as to what might be the issue. I'm planning to use NuttX for High Altitude balloons, and I'm preparing the groundwork for the rest of my team to then split the work between us. Which involve interacting with SATCOM modules, GPS, radios, etc. And I'm trying to do something very basic, but I'm having issues. I want to be able to validate that the UART6 is working well, so I can validate that the porting is working for this peripheral. And I'm trying to simply send some data down the line with nsh. With this command: ``` nsh> echo "test" > /dev/ttyS1 ``` But I'm not seeing anything on my Saleae logic analyzer. Here's the configuration I'm using for the UART on the Nucleo-H753ZI: ``` CONFIG_STM32H7_USART3=y CONFIG_STM32H7_USART6=y CONFIG_ARCH_HAVE_SERIAL_TERMIOS=y CONFIG_SERIAL=y CONFIG_SERIAL_CONSOLE=y CONFIG_MCU_SERIAL=y CONFIG_STANDARD_SERIAL=y CONFIG_SERIAL_NPOLLWAITERS=4 CONFIG_USART3_SERIAL_CONSOLE=y CONFIG_USART3_SERIALDRIVER=y CONFIG_USART6_SERIALDRIVER=y CONFIG_USART6_RXBUFSIZE=252 CONFIG_USART6_TXBUFSIZE=252 CONFIG_USART6_BAUD=115200 CONFIG_USART6_BITS=8 CONFIG_USART6_PARITY=0 CONFIG_USART6_2STOP=0 ``` In my board.h I have this configured for the UART6: ``` /* USART6*/ #define GPIO_USART6_TX (GPIO_USART6_TX_1 | GPIO_SPEED_100MHz) /* PC6 AF7 */ #define GPIO_USART6_RX (GPIO_USART6_RX_1 | GPIO_SPEED_100MHz) /* PC7 AF7 */ ``` Which is based on this config: https://os.mbed.com/platforms/ST-Nucleo-H743ZI/, I've also confirmed this in ST user manual and datasheets. And it's similar to the initialization of that UART in the linum-stm32h753zi: https://github.com/apache/nuttx/blob/master/boards/arm/stm32h7/linum-stm32h753bi/include/board.h#L379 And of course I've configured my Saleae logic analyzer to use 115200 baudrate, 8bit, no parity bit. [image.png] And here's the NSH where I try to send data down the UART6: [image.png] But nothing happens on my Saleae. I'm at the point of going through GDB and checking if there's indeed data being written down the register, but I thought I'd ask the community for guidance in resolving this issue in parallel. Thanks in advance! Best regards, Ludovic Vanasse Embedded Software Developper 1 514 475-0447 [https://drive.google.com/uc?export=view&id=1C4oeXOxjzz0SdirW122e2_8tXvfNEY13]
