RS232 Communication

[edwin marcellin]

Posted on April 17, 2018 at 16:53

Hello,

I have a STEVAL-FKI868V1 based on a Nucleo L152RE board and i would like to connect a RS232 to my RX pin to get the information and then send it when i click on the button.

So my main problem is about the code to developp to get the information from the RX.

Is someone could help me, please.

Thx

[Tesla DeLorean]

Posted on April 17, 2018 at 17:25

RS232 specifically, using a level converter like a MAX3232? Or serial communications using a USART more generally?

The Nucleo board provides for a VCP (Virtual Serial Port) connection to the PC via the ST-LINK, one can open this up in a Terminal application in Windows/Linux

The Cube L1 libraries should have assorted examples for USART connectivity.

http://www.st.com/en/embedded-software/stm32cubel1.html

 

>>So my main problem is about the code to develop to get the information from the RX. Is someone could help me, please.

Sounds like a school or work assignment, generally you're expect to do that work yourself.

[edwin marcellin]

Posted on April 17, 2018 at 17:44

Thank you.

No i have a module from Precla Molen that communicate in RS232. So i will do in USART. 

>>Sounds like a school or work assignment, generally you're expect to do that work yourself.

Yes usually but i have to do a quick proof of concept without spending that much time just to get information from sensors... I wanted to test this technology that i do not know.

I also have a pb IAR. I can only connect my device once. After that i have to delete everything and install it again, because i cannot rebuilt all.

[Tesla DeLorean]

Posted on April 18, 2018 at 22:56

The micro-controller will not accept RS232 level directly, you will need to interface to one of the available USART using a MAX3232 type device to convert the levels.

http://www.ti.com/lit/ds/symlink/max3232.pdf

 

[edwin marcellin]

Posted on April 19, 2018 at 09:05

Thank you.

So if I sum up the hardware part:

1. My sensor is connected to a box that gives me an output in RS232.

2. I connect the RX/TX from RS232 to a MAX3232

3. To do so, I just have to connect 4 connectors :

a. DOUT to TX (RS232)

b. RIN to RX (RS232)

c. Power to 3,3V or 5V to an external power

d. VCC to the ground (RS232)

4. Then I can connect the microcontroller :

a. DIN from MAX323 to the TX PA2 of the microcontroller

b. ROUT form MAX323 to the RX PA3 of the microcontroller

5. Depending on the voltage, I have to put 4 capacitors

Do I need a minimal current for the power supply dimension? Does the microcontroller have an output in 5v?

Thank you for helping

De : Clive One

Envoyé : mercredi 18 avril 2018 22:57

À : Marcellin Gros, Edwin (RC-FR EM TI)

Objet : Re: - Re: RS232 Communication

STMicroelectronics Community <https://community.st.com/?et=watches.email.thread>

Re: RS232 Communication

reply from Clive One<https://community.st.com/people/Turvey.Clive.002?et=watches.email.thread> in Interface and Connectivity ICs - View the full discussion<https://community.st.com/message/194315-re-rs232-communication?commentID=194315&et=watches.email.thread&sharpcomment-194315>