topic Re: The question about uart communication in Model-Based Design Toolbox (MBDT)

The question about uart communication

260068845 — Sun, 05 May 2019 07:19:28 GMT

Hello, engineers,

I encountered some problems when using the MPC5744P uart communication routine. In the 'uart_echo_mpc574xP', I can receive a U8 element in the serial port 1 interrupt and output it to the serial port, but I want to transfer an array and adjust the receiving size to 10. The other did not make adjustments, but the program did not receive 10 elements and returned as I expected. May I ask where is the problem? Thank you!!

Re: The question about uart communication

constantinrazva — Mon, 06 May 2019 13:26:11 GMT

Hello 260068845@qq.com‌,

Can you attach your model ?

Kind regards,

Razvan.

Re: The question about uart communication

260068845 — Mon, 06 May 2019 13:45:19 GMT

Of course, the file is in the attachment.

Re: The question about uart communication

constantinrazva — Wed, 08 May 2019 15:39:18 GMT

Hello 260068845@qq.com‌,

So the way the UART transmit/receive blocks work is the following:

- Receive - here you have an input to tell it what size you are expecting to receive (number of bytes)

- Transmit - the transfer size will be automatically set to the dimension of the input (e.g.: if you are using a data store memory block with size 10, you'll start sending 10 bytes)

In your model, by sending directly the output of UART_Receive to the input of UART_Transmit, Simulink sees that as having size 1, so you end up with a 1 byte UART transmit. To fix this, you can put the data in a data store memory (as you can see in the model attached by me). This way, Simulink will see this as a 10B variable, so the transfer size will be set accordingly.

Kind regards,

Razvan.