Timer2 does not work after including MySensors.h

TSD

"The application" in this case is just a blinking LED. I intend to use the ISR to read out a sensor and send the data with MySensors. But because I couldn't get the ISR to work, I reduced "the application" to an LED to keep this discussion focused on the real issue.

Yes, it always compiles, whether I include MySensors.h or not, and whether I use Arduino IDE or Atmel Studio.

It's just that the LED doesn't always blink. In fact, the LED only blinks if I compile with Atmel Studio and don't include MySensors.h.

I cannot use a serial monitor, because the custom node only has an ISP interface to program the MCU, there's no USB or anything like that.

mfalkvidd

@tsd my guess is that there is a problem with wiring to the radio, or that MySensors is unable to connect to your gateway.

In both those cases, MySensors will never reach setup() or loop().

What do the logs from your gateway say?
If you add something to presentation(), does the presentation reach your gateway?

TSD

@mfalkvidd
I was testing without the radio even attached, to try and simplify the problem.

But I reconnected the radio and expanded my example sketch to include a battery voltage measurement, that is transmitted to the GW with the RFM69 radio. The MySensors part of the sketch runs well, but the LED on pin 3 does not blink.

#define MY_NODE_ID 6
#define MY_RADIO_RFM69
#define MY_IS_RFM69HW
#define MY_DEBUG

#define LEDPIN 3

#include <MySensors.h>

MyMessage msgVcc(1, V_VOLTAGE);


int LEDstate = 0;
volatile byte counter;
ISR(TIMER2_OVF_vect) {

	++counter;
	if (counter == 0) {
		digitalWrite(LEDPIN,(LEDstate) ? HIGH : LOW);
		LEDstate = !LEDstate;
	};
}

void presentation()
{
	sendSketchInfo("Vbat", "1.0");
	present(1, S_MULTIMETER);

}

void setup()
{
	// Configure timer 2
	bitSet(ASSR,AS2);                // Select external clock for timer2
	TCCR2B = bit(CS22) | bit(CS20);  // Set clock divider to 1024
	bitSet(TIMSK2, TOIE2);           // Set timer 2 Overflow Interupt Enable (Timer Interupt Mask)
	
	// Configure LED
	pinMode(LEDPIN,OUTPUT);
	digitalWrite(LEDPIN,HIGH);
	
	sei();
}

void loop()
{
	if (counter) {
		counter = 0;
//		digitalWrite(LEDPIN,(LEDstate) ? HIGH : LOW);
//		LEDstate = !LEDstate;
	}
	
	long vcc = readVcc();      // Read battery voltage
	send(msgVcc.set(vcc, 1));  // Send battery voltage
	sleep(2000);               // Sleep 2s

}


long readVcc() {
	// Read 1.1V reference against AVcc
	// set the reference to Vcc and the measurement to the internal 1.1V reference
	#if defined(__AVR_ATmega32U4__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
	ADMUX = _BV(REFS0) | _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
	#elif defined (__AVR_ATtiny24__) || defined(__AVR_ATtiny44__) || defined(__AVR_ATtiny84__)
	ADMUX = _BV(MUX5) | _BV(MUX0);
	#elif defined (__AVR_ATtiny25__) || defined(__AVR_ATtiny45__) || defined(__AVR_ATtiny85__)
	ADMUX = _BV(MUX3) | _BV(MUX2);
	#else
	ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
	#endif

	delay(2); // Wait for Vref to settle
	ADCSRA |= _BV(ADSC); // Start conversion
	while (bit_is_set(ADCSRA,ADSC)); // measuring

	uint8_t low  = ADCL; // must read ADCL first - it then locks ADCH
	uint8_t high = ADCH; // unlocks both

	long result = (high<<8) | low;

	result = 1125300L / result; // Calculate Vcc (in mV); 1125300 = 1.1*1023*1000
	return result; // Vcc in millivolts
}

The GW log looks as expected, and repeats every 2 seconds:

11-8-2018 11:21:18node: b9b6269f.12ee68
msg.payload : string[73]
"0;255;3;0;9;2046448 TSF:MSG:READ,6-6-0,s=1,c=1,t=38,pt=7,l=5,sg=0:3319.0↵"
11-8-2018 11:21:18node: b9b6269f.12ee68
msg.payload : string[18]
"6;1;1;0;38;3319.0↵"

11-8-2018 11:21:20node: b9b6269f.12ee68
msg.payload : string[73]
"0;255;3;0;9;2048732 TSF:MSG:READ,6-6-0,s=1,c=1,t=38,pt=7,l=5,sg=0:3319.0↵"
11-8-2018 11:21:20node: b9b6269f.12ee68
msg.payload : string[18]
"6;1;1;0;38;3319.0↵"

However, the LED that should be toggled from the ISR, doesn't blink. The LED does blink with the code that I showed at the start of this thread (without any MySensors stuff).

My goal is to start the measurement and send the result from the ISR and not from the main loop to save more power. The current consumption during sleep is about 3.5uA now. I hope to get to around 1uA if I use timer 2. I've seen examples of people using timer 2 with the RTC, so I don't understand why this doesn't work in my case.

Hope the issue is more clear now. Does this make any sense to you?

mfalkvidd

@tsd nice work.
If you by "send the result from the ISR" mean sending using MySensors, it won't work. Inside an ISR, interrupts and timers are disabled so communicating with the radio is impossible. Also, sending would take way too much time. ISRs are meant to be very short.

Are you sure timer2 will increment while the mcu is sleeping? I know millis() will never increment during sleep. Maybe the same happens to timer2? What happens if you use wait() instead of sleep()?

mfalkvidd

Might be interesting to check if @ewasscher ever got around to implementing the stuff discussed in https://forum.mysensors.org/topic/2555/support-for-wake-up-by-timer2-instead-of-wd

scalz

@TSD
it's more clear now, because with the stripped version it could have been lot of other things :)

you'll need to make your own sleep function. because for the moment, powerdown mode only is available in MySensors. and as you may know it's not good for your timer2 (you need powersave mode).

TSD

@mfalkvidd, @scalz
Thanks, now we're getting somewhere. When I use wait(), the LED blinks. That makes sense if sleep() uses power down mode, which turns off almost everything, including timer 2.

I'll read the sensor and send the data (with MySensors) from the counter in the main loop. Then I'll see if I can get the MCU to sleep while leaving timer2 on with extended standby mode.

Thanks for your help!

TSD

@mfalkvidd @scalz
I tried first to disable the RFM69 with the _radio.sleep() function:

 

#define MY_NODE_ID 6
#define MY_RADIO_RFM69
#define MY_IS_RFM69HW
#define MY_DEBUG
#define MY_DEBUG_VERBOSE_RFM69

#define LEDPIN 3

#include <MySensors.h>

MyMessage msgVcc(1, V_VOLTAGE);

int LEDstate = 0;
volatile byte counter = 0;
int PostScaler = 0;

ISR(TIMER2_OVF_vect) {
	++counter;
}

void presentation()
{
	sendSketchInfo("Vbat", "1.0");
	present(1, S_MULTIMETER);
}

void setup()
{
	// Configure timer 2
	bitSet(ASSR,AS2);                // Select external clock for timer2
	TCCR2B = bit(CS22) | bit(CS20);  // Set clock divider to 1024
	bitSet(TIMSK2, TOIE2);           // Set timer 2 Overflow Interupt Enable (Timer Interupt Mask)
	
	// Configure LED
	pinMode(LEDPIN,OUTPUT);
	digitalWrite(LEDPIN,HIGH);
}

void loop()
{
	if (counter) {
		counter = 0;
		
		// Blink LED
		digitalWrite(LEDPIN,(LEDstate) ? HIGH : LOW);
		LEDstate = !LEDstate;
		
		// Measure battery voltage and send data to gateway
		if (PostScaler == 2) {
			
			_radio.receiveDone();      // Turn on radio
			long vcc = readVcc();      // Read battery voltage
			send(msgVcc.set(vcc, 1));  // Send battery voltage
			_radio.sleep();            // Sleep radio
			
			PostScaler = 0;
		}
		PostScaler++;
		sei();
	}
	
	wait(2000);
	
}


long readVcc() {
	// Read 1.1V reference against AVcc
	// set the reference to Vcc and the measurement to the internal 1.1V reference
	#if defined(__AVR_ATmega32U4__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
	ADMUX = _BV(REFS0) | _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
	#elif defined (__AVR_ATtiny24__) || defined(__AVR_ATtiny44__) || defined(__AVR_ATtiny84__)
	ADMUX = _BV(MUX5) | _BV(MUX0);
	#elif defined (__AVR_ATtiny25__) || defined(__AVR_ATtiny45__) || defined(__AVR_ATtiny85__)
	ADMUX = _BV(MUX3) | _BV(MUX2);
	#else
	ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
	#endif

	delay(2); // Wait for Vref to settle
	ADCSRA |= _BV(ADSC); // Start conversion
	while (bit_is_set(ADCSRA,ADSC)); // measuring

	uint8_t low  = ADCL; // must read ADCL first - it then locks ADCH
	uint8_t high = ADCH; // unlocks both

	long result = (high<<8) | low;

	result = 1125300L / result; // Calculate Vcc (in mV); 1125300 = 1.1*1023*1000
	return result; // Vcc in millivolts
}

However, the radio doesn't turn off at all. Is there anything else that needs to be configured before this function can be used?

mfalkvidd

@tsd this is way to deep for my knowledge unfortunately. Sorry.

TSD

@mfalkvidd Do you know anyone that might know more about this?

scalz

@TSD
I've not digged and not time to replicate your setup, but I have a suspicion with wait()
Does it help by using delay() instead of wait().
you won't use wait() if you make your own sleep() I think, and maybe you'll also need to make your custom wait() if needed.
Because wait() purpose is :

handle wdt, leds etc (see doYield)
incoming radio msg, radio link

When you sleep radio with low level function like you do, then a few vars may be not updated in mysensors machine (like transportActive I think)
So mysensors machine does not know you disabled/slept the radio (whereas when using mysensors and sleep in regular way it knows it of course).
Then when you call wait(), mysensors machine will try to check link (as the state variable has not been updated), link check fails and then it reinit radio. no sleep!

Not checked on my side, but it could be that :)

TSD

@scalz
Your hunch was correct! When I use delay(), the current drops to 4.6mA (from >20mA). So now I can start turning off MCU peripherals to reduce the current further.

By the way, is there good documentation to understand how all these MySensors functions work? Or do I just have to work with the Doxygen stuff and plough through all the relevant .h and .cpp files?

scalz

@TSD
glad to hear i helped you.
you have to work with doxygen and sources

Timer2 does not work after including MySensors.h

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