UART example? about rp-hal HOT 4 CLOSED

What does the frequency parameter mean

In any processor, different parts of the circuit take in a clock from one of a number of sources and divide it up to get the frequency they need to operate correctly.
The clock they take this from will usually be part of a clock tree

In the case of a UART peripheral, the input clock is some multiple of the target baud rate to allow for oversampling the signal and other processing. On the Pico in particular it needs to be at least 16x the frequency of the baud rate you're targeting - which probably explains why you're getting gibberish on the Rpi3 when you aren't setting it high enough.
You want it to either be a multiple of the target baud or significantly greater, otherwise the actual baud rate will be too far from the desired rate to work correctly.
The pico datasheet describes this in more detail.
If you look at figure 59 on page 437 of the datasheet, you'll see the source clock signal listed as as UARTCLK.
The requirements for the UART peripheral clock input are described in much greater detail on page 439, section 4.2.3.2. UART operation.

What pins are used for the peripherals

Rp2040 has a pin mux (multiplexer) that allows pins to connect to different peripherals.
Permitted mappings are also listed in the datasheet on page 13: 1.4.3 GPIO Functions

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Thank you, that clarifies it.

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Can you share working example? I have issues where UartPeripheral::enable hangs board and I have no idea what I'm doing wrong

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Please open a new issue rather than commenting on an already closed one.

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