STM32G431 schematic review

[tuncayarda]

Hello,

I designed a custom control board based on STM32G431CBT6 and before manufacturing the PCB I would like to make sure there are no fundamental hardware mistakes.

My main concern is not firmware but hardware connections.

I would appreciate if you can review especially:

• SWD programming interface connections

• Power supply and decoupling capacitors

• BOOT0 and NRST configuration

• VDDA and VREF+ connections

• CAN transceiver interface (TJA1051/3 with VIO = 3.3V)

• Anything that may prevent programming or startup

The goal is to verify that the MCU can be programmed and start reliably after assembly.

I am attaching the schematic below.

Thank you very much for your time.

MCU: STM32G431CBT6

Supply: 3.3V regulator

Debugger: ST-Link via SWD

[TDK · Accepted solution]

• PC13 shouldn't be used to drive an LED.
  • 

• NRST (PG10) does not need an external pullup, as it has an internal one. This will work though.
• I recommend using a standard debug header rather than 4-pins that you need to connect manually. Note that programmers typically don't provide power.

Otherwise, looks good.

[mƎALLEm]

For the relays control I suggest a GND isolation/separation using optocouplers to avoid any high-voltage spikes, and noise generated by relays coil and the relay switching, otherwise you may face unwanted resets of the MCU.

[Andrew Neil]

Include NRST on the programming connector.

If possible, have a UART for diagnostics

[Chris21]

"BOOT0 and NRST configuration"

You don't have a provision to use BOOT0.

Consider moving your CAN_RX to a different pin so that you can utilize BOOT0.

And as Andrew said, "If possible, have a UART for diagnostics" + reprogramming flash with bootloader.

[Andrew Neil]

---

@TDK wrote:

• PC13 shouldn't be used to drive an LED.

---

Indeed.

But it is OK for these pins to sink current; eg, for an LED:

https://community.st.com/t5/stm32-mcus-products/stm32f030-pc13-14-15-current-sink-limits/m-p/721081/highlight/true#M261048

[Andrew Neil]

@tuncayarda all of your LED series resistors are 220 ohm:

Shouldn't the 12V ones (D2-3, D5-6) be higher ?