STM8L050J3: SWIM and USART TX on same pin?

[Cpg2]

Hi. I am designing Schematic for STM8L050J3 chip. In that, pin1( first pin) , in datasheet they mentioned as SWIM in port A0 of pin1 and USART TX in port A2 of pin1. I want to use this pin as SWIM for programming as well as USART for data transmission. How can i use that? Is there a way?  

[Peter BENSCH]

Welcome @Cpg2, to the community!

You can use pin 1 for SWIM as well as for a UART. This question is also answered in the data sheet of the STM8L050J3, section 3.16:

Recommendations for SWIM pin (pin#1) sharing
If the SWIM pin should be used with the I/O pin functionality, it is recommended to add a ~5 seconds delay in the firmware before changing the functionality on the pin with SWIM functions. This action allows the user to set the device into SWIM mode after the device power on and to be able to reprogram the device. If the pin with SWIM functionality is set to I/O mode immediately after the device reset, the device is unable to connect through the SWIM interface and it is locked forever (if the NRST pin is not available on the package). This initial delay can be removed in the final (locked) code.

Does it answer your question?

Regards
/Peter

[Cpg2]

Thank you sir. I also have another question. Can that pin be used for SWIM and USART at a time in a parallel manner? I will also program and the data also will be transmitted using USART . Will that affect the pin?. or one pin used at a time?

[Peter BENSCH]

The pin can only execute one function at a time, i.e. either SWIM or USART. Both at the same time, e.g. for debugging, is not possible.

However, you can switch the function at any time, i.e. from SWIM to USART or vice versa, but this is not practical for debugging.