Teensy and sleep mode

Projects Programming
1

Im trying to implement a simple sleep mode with interrupt wake up on my Teensy 3.2 but when i try to compile i get this error:

D:\_a\Arduino\hardware\teensy\avr\cores\teensy3/avr/sleep.h:36:23: error: expected primary-expression before 'asm'

 #define sleep_cpu()  (asm("wfi"))

                       ^

D:\_a\Arduino\hardware\teensy\avr\cores\teensy3/avr/sleep.h:38:23: note: in expansion of macro 'sleep_cpu'

 #define sleep_mode()  sleep_cpu()

                       ^

d:\Users\SIMETRI_DEV\Documents\Arduino\InterSleep\InterSleep.ino:26:3: note: in expansion of macro 'sleep_mode'

   sleep_mode();

   ^

D:\_a\Arduino\hardware\teensy\avr\cores\teensy3/avr/sleep.h:36:23: error: expected ')' before 'asm'

 #define sleep_cpu()  (asm("wfi"))

                       ^

D:\_a\Arduino\hardware\teensy\avr\cores\teensy3/avr/sleep.h:38:23: note: in expansion of macro 'sleep_cpu'

 #define sleep_mode()  sleep_cpu()

                       ^

d:\Users\SIMETRI_DEV\Documents\Arduino\InterSleep\InterSleep.ino:26:3: note: in expansion of macro 'sleep_mode'

   sleep_mode();

   ^

Error compiling for board Teensy 3.2 / 3.1.

And here is my code:

#include <avr/sleep.h>
#include <avr/interrupt.h>

#define SWITCH 14
#define LED    15
#define LED2   16

void func(void)
{
  digitalWrite(LED, HIGH);
  //sleep_disable();
}

void setup() {
  pinMode(SWITCH, INPUT);
  pinMode(LED, OUTPUT);
  pinMode(LED2, OUTPUT);
  
  set_sleep_mode(SLEEP_MODE_IDLE);
  sleep_enable();
  attachInterrupt(SWITCH, func, LOW);
}

void loop() {
  sleep_mode();
  digitalWrite(LED, LOW);

  digitalWrite(LED2, HIGH);
  delay(1000);
  digitalWrite(LED2, LOW);
  delay(1000);
}
2

thunderbootyclap:
...my Teensy 3.2...

#include <avr/sleep.h>
#include <avr/interrupt.h>

Does the Teensy 3.2 have an AVR processor?

3

The AVR code won't work because the Teensy 3.2 is an ARM processor. You should ask this on the Teensy forum forum.pjrc.com

Pete

4

cores/teensy3/avr/sleep.h

/* Simple compatibility headers for AVR code used with ARM chips
 * Copyright (c) 2015 Paul Stoffregen <paul@pjrc.com>
...

One could reasonably expect that the code at least compiles.

However, the functionality might not be exactly the same as on AVR:

#define SLEEP_MODE_IDLE         0
#define SLEEP_MODE_ADC          0
#define SLEEP_MODE_PWR_DOWN     1
#define SLEEP_MODE_PWR_SAVE     1
#define SLEEP_MODE_STANDBY      1
#define SLEEP_MODE_EXT_STANDBY  1

#define set_sleep_mode(mode)    // TODO: actually set the mode...
#define sleep_enable()
#define sleep_disable()
...

This is what causes the error:

#define sleep_cpu()             (asm("wfi"))

It turns out that the compiler does not like the () around asm().

5

Indeed Paul has done a huge amount of work to make transition from AVR to ARM as painless as possible.
I had the vague memory that the sleep modes and how to enter them with ARM was a lot different than AVR and so it would be a good idea to ask on the PJRC forum about putting a T3.2 to sleep.
Although I have multiple Teensys of various flavours, I have only used sleep on the Teensy2 and Teensy2++, which is AVR, and not on the Teensy 3.x which are ARM.

I think there was another post recently in which someone ran afoul of a macro which surrounded its argument with parentheses. Has the compiler changed or was the code ported from something in which that is acceptable?

Pete

6 
#define sleep_cpu()  do { asm("wfi") } while(0)

The other is actually valid C(++) syntax. For example...

  (Serial.begin(250000));

Apparently, "asm" side steps the parser.