So [Todd] has set out to build an Arduino frequency counter for a Kenwood TS-520S HF ham radio. This post (and the video found after the break) doesn’t cover the entire project. It’s rather ...

However, Arduino also offers this board without headers ... Their onboard LEDs are connected to pin D13, and their serial RX/TX pins are on pins D0 and D1, respectively. Additionally, the Nano ...

Another noteworthy feature is the RX-TX switch function. Traditional Arduino boards assign digital pins in a specific order, but the UART interface on the RP2350 has a different configuration.