Scamp2 UART Pins

Mapping UARTs to Pins (Scamp1 and Scamp2)

On a Scamp1 or Scamp2 (only) the UARTs must be mapped to a pin on the connector. This can be any pin, with the exception of pins 7 and 8 for Rx and 4, 7, and 8 for Tx. For example to map UART1's Rx to pin 4, place 4 on the stack and then call the word rx1pin:

4 rx1pin

Unfortunately there is a bug in the word to allocate Tx to a pin, so this has to be done manually. This is done by writing a function code to the appropriate register for a given pin (known as a RP pin). Tx1 has the function code 3 andTx2 has the function code 5. Use the following table for Forth commands to allocate Tx pins.

Scamp Pin	RPx	Forth Command for Tx1	Forth Command for Tx2
0	RP0	`#3 $03d6 c!`	`#5 $03d6 c!`
1	RP1	`#3 $03d7 c!`	`#5 $03d7 c!`
2	RB2	`#3 $03d8 c!`	`#5 $03d8 c!`
3	RP3	`#3 $03d9 c!`	`#5 $03d9 c!`
4	-
5	RP5	`#3 $03db c!`	`#5 $03db c!`
6	RP6	`#3 $03dc c!`	`#5 $03dc c!`
7	-
8	-
9	RP7	`#3 $03dd c!`	`#5 $03dd c!`
10	RP13	`#3 $03e3 c!`	`#5 $03e3 c!`
11	RP14	`#3 $03e4 c!`	`#5 $03e4 c!`
12	RP15	`#3 $03e5 c!`	`#5 $03e5 c!`

So for example, to allocate Tx1 to Scamp pin 5:

#3 $03db c!

Note that there is no requirement for both a receiver and transmitter to be allocated to pins. If you only need to receive data, you only need to allocate a receiver. Similarly, if you only need to transmit data, only a transmitter need be allocated.

On a Scamp3, the UARTs are already mapped to dedicated pins, so pin allocation is unnecessary.

Learn : Interfacing : Serial Communication

Mapping UARTs to Pins (Scamp1 and Scamp2)​

Mapping UARTs to Pins (Scamp1 and Scamp2)