Hi,
Is there any example code to boot a new firmware to the stm32L by USART1? should the boot0 pin pulled high by external device during the USART communication?
Review the documentation www.st.com/.../CD00264342.pdf
Download the "Flash Loader Demonstrator" is has source code, or you can just implement the protocol as described in the documentation.
There are also open source examples, a quick Google might get you started.
Thanks for the link. just I don't know about the state of pin Boot0. Should it be pulled high just for interrupting the MCU and then pulled low? I am using another STM32 to download a new firmware. The new MCU holds the control of Boot0 while communicating with USART.