AFSoftSerial questions Moderators: adafruit_support_bill, adafruit

[zlite]

I'm having a little trouble using AFSoftSerial to read GPS strings and have two questions:

1) Why do the examples always tend to use pin 2 and 3 for Rx and Tx? Those are the hardware serial pins--exactly the ones you don't need for software serial.

2) Can you use any digital pins for Rx and Tx?

[mtbf0]

uh, 0 and 1 are hardware rx and tx.

[zlite]

Are you referring to the physical pins or logical pins? According to the official pin mapping the Rx and Tx are on physical pins 2 and 3. Those are of course digital pins 0 and 1.

So the AFSoftSerial is assuming that the pin number refer to logical pins, and "2" and "3" are actually physical pins 4 and 5?

[mtbf0]

yes. which is to say i don't know because all my arduini are boarduini and rbbb's, but the 2 and 3 refer to digital pin 2 and digital pin 3.

[adafruit]

like all arduino libraries, the pins indicated are the digital pin names, not 'actual' pin names

[zlite]

like all arduino libraries, the pins indicated are the digital pin names, not 'actual' pin names

Many thanks for the clarification on that, which I've been confused by from the start. I wonder what to do with functions that can use both analog or digital pins--I guess you have to refer to the analog ones by their "official" names, such as PC0?

[mtbf0]

I guess you have to refer to the analog ones by their "official" names, such as PC0?

no. don't do that. when using them for digital i/o they are digital 14-19. PC0 is a constant that indicates pin number 0 in portC. so if you were to use, for instance

Code: Select all | TOGGLE FULL SIZE

digitalWrite (PC0, HIGH);

it would be the same as if you'd used

Code: Select all | TOGGLE FULL SIZE

digitalWrite(0, HIGH);

and you'd be writing a 1 to digital pin 0, the receive pin for the hardware serial interface.

[zlite]

Many thanks for the clarification--I don't know how I missed that so far, but this will save me many baffling bugs going forward.