Wizfi250 hardwer flow control


Hi Everybody!

Wizfi250 (UART1) has hardware flow control. User can enable or disable it. Moreover has pins RTS and CTS to carry hardware flow control. But the specification are say “UART1_RTS I/O” and “UART1_CTS I/O”. This means does not specified which one is output of wiz250, and which one is input of them. According my research CTS is out of wiz250, RTS is input of wiz250, but I’m not sure.

Function of this flow control also not specified. It can be control traffic from host to wiz250, or control traffic from wiz250 to host or can be bidirectional. The direction of the pins is imply it is control traffic from host to wiz250, but I’m not sure.

Any advise?


Hi, kzsolt2

–> From what I find, CTS is input, RTS is output like below.
(This picture is from ST chip’s datasheet)

Because WizFi250 and host MCU have CTS/RTS pin, it can be controlled bi-directional.

Also, If you are using a UART with baudrate below 115200, you do not need to use the RTS / CTS pin.



Dear Tom!

The wizfi deafult is: hardware flow control disabled
Ok, then I limit to 115200 (I no need more) and do not use hw flow control.

If my reverse engineering is correct, then:
wizfi nCTS out pin need to connect to MCU’s nCTS in pin.
wizfi nRTS in pin need to connect to MCU’s nRTS out pin.

To clearify this wizfi250pg at appendix refer to HW flow control, but does not draw a correct pin connection between MCU and Wizfi.

Best Regards, kzsolt2