Wiring UART communication between Arduino Nano SoftSerial and STM32F103C8T6

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1

Hello!

I have an STM32F103C8T6 (BluePill) as master device. It need to collect some data from and Arduino Nano over UART, so the communication is monodirectional Nano -> STM32 -> PC

At a Nano, i can define any two digital ports to be softserial (D2, D3) . On the STM32 side, i use now the Serial2 (A2, A3) with an CP2104 USB TTL on 5V to communicate between STM32 and a PC, but can i use in same time also the Serial1 (B6, B7) to communicate between STM32 and the Arduino Nano?

Is enough that i crosswire the B6 and B7 at STM32 side with D3 and D2 Arduino nano Side (Tx->Rx, Rx->Tx) or i need to connect also GND and 5V?

I think the Nano will works with this digital pins at 5V, is this a problem on STM32 side?

2

a Blue Pill has USB and the core makes is accessible as Serial. so why the USB TTL?

the Serial1 pins A9 an A10 (or B6 and B7) are 5 V tolerant, the Serial2 pins A2 and A3 are not 5 V tolerant.
always wire ground together for TTL.
how is the Nano powered? do you want to power the Nano from STM32? the wire 5 V pins together.

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do you use the STM32 as Arduino? which core do you use?

3

@Juraj

I have configured my software on PC to serch for Serial and i will now not change it to USB. Also, i don't need a high speed and a sensors and the rest of electronics are connected to 220V AC, and in "worst case" is a bit of lover the possibolity to destroy os a PC if is a connection to PC over TTL but direct.

Because i don't use USB on STM32, i have connected direct to 5V source (2A USB charger) to Arduino VCC and to 5V pin on STM32. Ground can i connect both to negative pole.

The STM32 device is used to communicate with PC and to encrypt the communication with AES. Nano is to slow to use AES.

So if can understand good, i need only this two pins (RX, TX), not more?

4

emilr:
@Juraj

I have configured my software on PC to serch for Serial and i will now not change it to USB. Also, i don't need a high speed and a sensors and the rest of electronics are connected to 220V AC, and in "worst case" is a bit of lover the possibolity to destroy os a PC if is a connection to PC over TTL but direct.

Because i don't use USB on STM32, i have connected direct to 5V source (2A USB charger) to Arduino VCC and to 5V pin on STM32. Ground can i connect both to negative pole.

The STM32 device is used to communicate with PC and to encrypt the communication with AES. Nano is to slow to use AES.

So if can understand good, i need only this two pins (RX, TX), not more?

only RX and TX.