Skip to main content
T
tsma
Visitor II
December 30, 2022
Solved

STM32L010F4P6 which pins are used by UART bootloader

  • December 30, 2022
  • 1 reply
  • 2627 views

Hello, I'm attempting to flash firmware to aforementioned microcontroller using STM32CubeProgrammer. I have connected ST-Link VCP port to PA2 and PA3 ports, and i can communicate with my application fine. I even erased flash memory so I could be sure that device is in Boot mode. Unfortunately, I cannot connect to bootloader, log from Programmer below:

 13:48:06 : Serial Port ttyACM0 is successfully opened.
 13:48:06 : Port configuration: parity = even, baudrate = 115200, data-bit = 8, stop-bit = 1.0, flow-control = off
 13:48:08 : Timeout error occured while waiting for acknowledgement.
 13:48:08 : Timeout error occured while waiting for acknowledgement.
 13:48:08 : Error: Activating device: KO. Please, verify the boot mode configuration and check the serial port configuration. Reset your device then try again...

I'm wondering if listing both PA9/PA10 and PA2/PA3 as UART ports in documentation has anything to do with it. How does bootloader determine which of both pairs to use? Can pullups on PA2/PA3 connected to inactive I2C bus (because STM acts as master, also because of that and pin alternate functions being almost universally poorly laid out I couldn't use PA9/PA10) have something to do with it?

    This topic has been closed for replies.
    Best answer by Tesla DeLorean

    It initially configures the UART-RX pin as a TIM input to measure the 0x7F bit pattern, then it uses that to initialize the UART and baud rate.

    You want to avoid noise/activity on any other pin it might recognize as input/data.

    Having a GPS receiver. or other device that starts squawking at startup can be problematic.

    1 reply

    M
    MM..1
    Graduate II
    December 30, 2022

    Read AN2606

    0693W00000Y7867QAB.pngFirst you need start bootloader and after this try connect. Start is pattern or jump from app

    T
    tsmaAuthor
    Visitor II
    December 30, 2022

    Well, both are USART2 on PA9/PA10 and USART2 on PA2/PA3, as I wrote in my question. And PA2/PA3 works with UART in my application. It just refuses to work with CubeProgrammer. I'm just puzzled how does bootloader configure USART to use either of pairs.

    T
    Tesla DeLoreanAnswer
    Graduate II
    December 30, 2022

    It initially configures the UART-RX pin as a TIM input to measure the 0x7F bit pattern, then it uses that to initialize the UART and baud rate.

    You want to avoid noise/activity on any other pin it might recognize as input/data.

    Having a GPS receiver. or other device that starts squawking at startup can be problematic.

    Terms & ConditionsAccessibility statement