AltSoftSerial strange behaviour

Projects Programming
1

Hi

I have an Arduino Uno connected via USB to my computer. There is a wire connection pin 8 to Tx and pin 9 to Rx. I am running the example sketch for AltSoftSerial:

#include <AltSoftSerial.h>

// AltSoftSerial always uses these pins:
//
// Board          Transmit  Receive   PWM Unusable
// -----          --------  -------   ------------
// Teensy 3.0 & 3.1  21        20         22
// Teensy 2.0         9        10       (none)
// Teensy++ 2.0      25         4       26, 27
// Arduino Uno        9         8         10
// Arduino Leonardo   5        13       (none)
// Arduino Mega      46        48       44, 45
// Wiring-S           5         6          4
// Sanguino          13        14         12

// This example code is in the public domain.

AltSoftSerial altSerial(8,9);

void setup() {
  Serial.begin(9600);
  while (!Serial) ; // wait for Arduino Serial Monitor to open
  Serial.println("AltSoftSerial Test Begin"); 
  altSerial.begin(9600);
  altSerial.println("Hello World");
}

void loop() {
  char c;
  if (Serial.available()) {
    c = Serial.read();
    altSerial.print(c);
  }
  if (altSerial.available()) {
    c = altSerial.read();
    Serial.print(c);
  }
}

If I upload the sketch with the wires connected, I get a crazy output on serial monitor and baud rate is 9600 - see attached picture.

If I disconnect the wires, then upload sketch, then re-connect wires, serial monitor displays "AltSoftSerial Test Begin". When I send any characters via serial monitor, nothing happens.

What is going on?

screenshot1.PNG
screenshot1.PNG1002×555 7.12 KB

2

On further investigation, I've noticed the following;

If I connect Pin8 to Rx and with nothing connected to Pin9, I then get the expected behavior on serial monitor(characters sent over serial monitor is echoed back). But pin 8 is supposed to receive and pin 9 transmit as far as I understand. This isn't making any sense to me.

Now, if Pin8 is connected to Rx and Pin 9 to Tx, serial monitor returns reversed question marks(⸮⸮⸮).

:confused:

3

I am wondering if my board may be faulty. May I please ask if someone can test the same code on their Uno and report back if the sketch works as expected or if you are having the same issue as me.
Thanks in advance.

4

please show us the wiring (as a drawing preferably ) And show us the code (within </> code tags) probably nothing wrong with the board.