STM32L433RCT6 - Which GPIO pins do I need to use for flashing using ST Link / Segger J-Link / UART / USB

[johngj]

I am designing my own PCB which uses the STM32L433RCT6

I want to ensure I have the necessary GPIO pins going to a connector so that I can flash/debug using the following interfaces:

Below are the GPIO pins I have brought out to connectors, have I missed anything or got anything wrong ?

1. ST link: For flashing and debugging during development

I have currently routed the following pins to a 6 pin connector:

• SWDIO (PA13)
• SWCLK (PA14)
• NRST
• BOOT0 (PH3)
• GND
• +3.3V

2. Segger J-Link: For flashing and debugging during development

I have currently routed the following pins to a 6 pin connector:

• SWDIO (PA13)
• SWCLK (PA14)
• NRST
• BOOT0 (PH3)
• GND
• +3.3V

3. UART: For firmware updates

I have currently routed the following pins to a 4 pin connector:

• LPUART Tx
• LPUART Rx
• GND
• +3.3V

Is LPUART suitable or does it need to be USART ?

4. USB: For firmware updates

I have currently routed the following pins to a USB connector:

• USB D+
• USB D-

In STM32CubeIDE, the SYS configuration has serial wire, JTAG (4 pins) and JTAG (5 pins).  

I noticed that JTAG (4 pins) uses an extra pin for "SWO" (PB3) and JTAG (5 pins) uses an extra pin "SYS_JRST" (PB4).

Would I need these pins too ? 

[mƎALLEm · Accepted solution]

Hello,

You need to check the AN2606 for the ST bootloader resources.

You can't use LPUART. Please refer to the table 152 for the bootloader resources available for USART / USB in STM32L43x.

For STLINK/JLINK, please refer to any Eval board schematics example: STM32L476G-EVAL.

PS: in next time it's recommended to separate the questions in multiple thread. It's hard to manage many questions in the same thread.

For example, you may ask: ST bootloader question in a thread and the STLINK/JLINK in another thread. Thank you.

[TDK]

SWO is not needed or used for flashing. Not sure if SYS_JRST is required for JTAG.

It's silly to program in so many different ways to flash the chip. Use SWD for development and be done with it. If user updates are needed, choose (LP)UART or USB and have those available. You will need to be able to jump to the bootloader for these, unlike with SWD.