![]() It’s also possible to send and receive packets without using SWO thanks to libraries like Segger RTT, but this is not standard and it needs a Segger probe like the ones you will find in the next section. It’s pretty much a reduced version of the JTAG that requires just 2 signal pins (SWD and SWCLK) and optionally a third one (SWO) to send and receive data. SWD: Serial Wire Debug is broadly used nowadays.JTAG: this is the classical interface, it was designed in the 90 and it needs 4 signal pins (plus power and some times a target reset).Now that we know that UART is not what we should be using, what can we replace it with? The answer is (for Cortex-M micros), one of the following interfaces: Finally, the serial to USB converter can only be used to send/receive data, but if we were to use the proper tools, we could do a full debugging of our target processor, including step by step execution, adding breakpoints or memory and registers inspection. Another important con is that we will need to reserve one UART for this purpose and typically not use it for anything else. The biggest disadvantage is that printing through UART interferes with the execution of the code, which means that our code can behave differently with and without logs. This is relatively simple to set up and it’s very cheap (a converter costs 2-3€).ĭespite being a very convenient approach, using the serial port usually falls short of our needs. ![]() The only thing we need to read that from the host computer is a serial to USB converter (usually known as FTDI, which is actually the name of the biggest manufacturer of these ICs). When starting a project, the most common way to make sure everything works fine (the hello world), is to print some messages through the UART. Programming and debugging system Interfaces
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