STM32L432 Power Problem with NRF24L01 and USART

[Min-Kyoung Kim]

I made NRF24L01 module using STM32L432.

I supplied 3.3V to MCU and NRF24L01.

So, I checked USART communication from STM32L432 to PC.

But I failed checking SPI to NRF24L01.

Below, Problems I have,

1. If I supply 3.3V to MCU(Actually whole module), GPIO Out doesn't work.
2. If I supply 2.0V(near 2.0v) to MCU, GPIO Out works.
3. As you know, if i supply 2.0v, I can't use USART because of power level.

Of course, I used same Firmware for above test.

In advance, Thank you for your answer.

Regards,

Min.

+++++ Circuit

SPI Line : PA1,4,5,6,7

MOD_VCC : supplying 2.0V and 3.3V

[Tesla DeLorean]

Check you don't have two pins driving in different directions against each other.

You'll need to carefully review the circuit, and see if you can isolate specifically what is wrong. Perhaps disconnect one of the SPI lines at a time.

[Min-Kyoung Kim]

This problem actually isn't SPI one.

At first, I thought the same thing.

But when I did the simple GPIO out test (other pin not connected to spi), GPIO out didn't work under 3.3V.

Under same Circuit and same Firmware, 2V and 3.3V supplying make other result.

Of course, when I supply 2V to my moduel, spi does work!

But I can't use USART in this moduel.

So is there any solution for the normal operation in 3.3V supplying.

i attached my STM32L432 circuit on my post.

[Tesla DeLorean]

You're going to have to own the board bring-up process, it is likely what it is attached to, or an issue with different MOD_VCC vs MOD_VDDA voltages.

Try tri-stating all the pins, and bring up a few at a time. Or bring up a board with just the STM32 in it and minimal parts to power it.

Running a L432KB here at 3.3V and my GPIO and USARTS seems to be working fine.