I wonder is it possible to change PCM.h 's lib use of 16-bit timer1 to another 8-bit? Now I'm getting

libraries\AltSoftSerial\AltSoftSerial.cpp.o (symbol from plugin): In function `AltSoftSerial::read()':

(.text+0x0): multiple definition of `__vector_11'

libraries\PCM\PCM.c.o (symbol from plugin):(.text+0x0): first defined here

collect2.exe: error: ld returned 1 exit status

exit status 1

when compiling

#include <PCM.h>
#include <AltSoftSerial.h>

An attempt to avoid XY problem: make AltSoftSerial work alongside with PCM-alike library on Arduino Nano v3 without SD.

I'm poorly familiar with timers and interrupts, so I'll be very grateful for any advice and suggestion!

1 Answer 1


It is not easy to make PCM sounds with the Arduino Uno or Nano. A few libraries can do that, but they use two timers: Timer1 and Timer2. Timer0 is already in use by Arduino. When using those libraries, the Arduino Nano is almost completely occupied to make sounds.

A software serial port also requires a lot from the Arduino Nano. The AltSoftSerial uses Timer1.

Those two will never work together. It is not possible.
For what do you need the serial port ?
Could that be done in a different way ?

The normal SoftwareSerial does not use a timer, but because it also occupies the Arduino Nano a lot, using SoftwareSerial together with a PCM sound at the same time will not work. Perhaps if you carefully design the sketch and never use them at the same time, it might work. I doubt if it will be reliable.

A better option is to swap the Arduino Nano for an Arduino Micro. Then you have a extra hardware serial port and you don't need the AltSoftSerial anymore. The library to make PCM sounds has to be compatible with the Arduino Micro. I suppose that not every PCM library is compatible.

The best option is to use a MP3 shield. Then you can send a command to play a MP3 sound. If you use a MP3 shield with a Arduino Micro or Arduino Leonardo or Arduino Mega 2560 or Arduino Zero or Arduino Due, then you have a extra hardware serial port and you don't need libraries that occupy the most of the Arduino board, and your sketch will be a normal sketch that does normal things.

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