6 years, 5 months ago.

Nucleo L432KC bootloader via UART failed

Hi, I met a problem using bootloader on pc to wirte program into STM32L432KC via UART. Here is the process I did : 1,I connect D1/Tx and D0/RX(PA9 and PA10 of STM32L432KC) to CH340 USB to UART board, 5V Vin and GND. USB to PC. 2, I connect 5V to pin 31 of STM32L432KC:PH3\BOOT0 , reset the ic, then pull PH3\BOOT0 = 0V. The LED do not blinky, which means the stm32L432KC is in boot mode. 3, I opened Flash Loader Demonstrator boot loader, chose the COM port , click next:

THen next:

The software can not read Flash Mapping, nor the target name.Can not do anything with this.

/media/uploads/yulumaxim/pastedimage_83.png /media/uploads/yulumaxim/pastedimage_84.png Checked in ST link Utility, no Read out protection.

So I do not know what is the problem ? Software or hardware ? Nucleo board or CH430 ? Thank you!

Can you manually select the TARGET ? See here:


Also, PA9 is STM32LF4 TX so connect to your CH340 RX. PA10 is RX on micro so connect to CH340 TX. BOOT0 should be kept HIGH (is 5 volt tolerant so ok to keep @ 5V). Then pulse reset.

See page 221 of this document for UART boot details:


What is your clock on the STM32L4 ?

posted by Sanjiv Bhatia 25 Apr 2017
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