smart-home/weather-sensor/firmware/main.c

#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/sleep.h>
#include <util/delay.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "nrf24l01.h"
#include "nrf24l01_definitions.h"
#include "bme280_interface.h"
#include "bme280_defs.h"


/* SPI: */
/* TODO: move to spi.h */
#define SPI_DDR       DDRB
#define SPI_SCK_PIN   PB5
#define SPI_MOSI_PIN  PB3
#define SPI_MISO_PIN  PB4

/* Debug LED: */
#define LED_DDR   DDRD
#define LED_PORT  PORTD
#define LED_PIN   PD3


char bool_case = 0;
int timer = 0;
int timer_max = 0;

volatile uint8_t cycle = 0;

volatile uint8_t interruptCounter;
volatile uint8_t executionFlag;


void Initialize_SPI(void);
void Enter_Power_Save_Mode(void);
void Exit_Power_Save_Mode(void);


/* TODO Notes for power saving:
 * - Power-save-mode needed -> SM2...0 bits written to 011
 * - Entering by issuing the SLEEP instruction -> What call in C?
 *   - Before executing the SLEEP instruction, write bit SE of the SMCR to 1
 * - Let Timer/Counter2 run with the necessary period and enable an interrupt.
 *   -> The Global Interrupt Enable bit in SREG has to be set.
 * - asynchronous/synchronous clock source?
 * - When waking up
 *   - Set PRR bits for needed peripherals
 * - 
 */
void Set_Up_Power_Save_Mode(void);
void Enter_Power_Save_Mode(void);


ISR( TIMER2_COMPA_vect )
{
	/* Do nothing as the interrupt is only used to wake up the MCU. */
}

int main (void)
{
	struct bme280_data sensorData;
//	uint8_t testRegisterContent = 0x0A;
//	uint8_t registerContent[5];
//	char registerContentString[30];
//	uint8_t lengthRead;
	uint8_t temp = 0;

	/* Enable the debug LED */
	LED_DDR |= (1 << LED_PIN);

	/* Initialize the SPI */
	Initialize_SPI();

	/* Initialize the nrf24l01 */
	Initialize_NRF24L01();
	// The NRF24L01 is now in the mode Standby-I.

	/* Configure the transmission parameters (Enhanced ShockBurst)*/
	Configure_Transmission();

	/* Initialize the BME280 */
	Initialize_BME280();
	Set_Up_Power_Save_Mode();


	/* Delay the change of the operating frequency by the function Enter_Power_Save_Mode for the
	 * first function pass. If it is changed before the ISP can flash the MCU the clocks of the ISP
	 * and MCU are mismatched and the flashing will fail.
	 */
	_delay_ms(500);

	while(1)
	{
		Enter_Power_Save_Mode(); // The MCU enters the Power Save Mode here.
		Exit_Power_Save_Mode(); // The MCU exits the Power Save Mode here.

		if (cycle == 0) // TODO cycle == 7 to execute this every 60 s
		{
			/* Re-Initialize the peripherals */
			Set_BME280_Pins();
			Set_NRF24L01_Pins();

			/* Get measurement and send it */
			BME280_Get_Measurement(&sensorData);
			NRF24L01_Send_Message((uint8_t*)&sensorData, sizeof(sensorData));

			if (temp == 0)
			{
				LED_PORT |= (1 << LED_PIN);
				temp = 1;
			}
			else
			{
				temp = 0;
				LED_PORT &= ~(1 << LED_PIN);
			}

			cycle = 0;
		}
		else
		{
			cycle ++;
		}
	}
}

void Initialize_SPI(void)
{
	/* TODO: move to spi.h */
	/* Set MOSI and SCK output, all others input */
	SPI_DDR = (1<<SPI_MOSI_PIN)|(1<<SPI_SCK_PIN);
	/* Enable SPI, Master, set clock rate fck/16 */
	SPCR = (1<<SPE)|(1<<MSTR);
}

void Set_Up_Power_Save_Mode(void)
{
	// Disable Brown-Out-Detection by setting the BODLEVEL 2:0 Fuses to 0b111 (should be default)
	// Disable the on-chip debug system by setting the DWEN Fuse to 1 (should be default)

	/* Disable some unused peripherals that are not used during operation of the weather station: */
	// The ADC is turned off by default
	ACSR &= ~(1<<ACD); // Analog comperator
	ACSR &= ~(1<<ACIE); // The interrupt bit has to be cleared after switchin of the analog comperator
	/*
	 * The Internal voltager reference is automatically disabled if the BOD, ADC and Voltage
	 * Reference are disabled
	 */

	/* Set up Timer/Counter2 */
	PRR &= ~(1<<PRTIM2); // Enable the timer 2 in the Power Reduction Register

	TCCR2A |= (1<<COM2A1)|(1<<COM2A0)|(1<<WGM21); // Set the timer to ClearTimer on Compare Match with output compare mode for channel A
	/* There is a problem: The maximum time until the counter 2 overflows is 262ms at the nominal
	 * core frquency of 1MHz and a timer prescaler of 1024.
	 * This can be attenuated by lowering the system frequency to 31.25 kHz via the clock prescaler
	 * (CLKPS3...0) of the register CLKPR. This gives a overflow time of 8.3s.
	 * The cycle time of one minute can thus be accomplished by setting the output compare register
	 * to 229. This spawns an interrupt every 7.5s which means the operation has to be executed
	 * every 8 interrupt calls.
	 */

	TCCR2B |= (1<<CS22)|(1<<CS21)|(1<<CS20); // Set the timer prescaler to 1/1024
	OCR2A = 229; // TODO: calculate this number from the wanted cycle time and the timer frequency.

	TIMSK2 |= (1<<OCIE2A); // Enable the Output Compare Match A Interrupt.

	/* Enable global interrupts: */
	sei();
}

void Enter_Power_Save_Mode(void)
{
	PRR |= (1<<PRTWI) | (1<<PRTIM0) | (1<<PRTIM1) | (1<<PRSPI) | (1<<PRUSART0) | (1<<PRADC); /* Only timer 2 is needed for wake-up interrupt */

	/* Set the clock prescaler for a frequency of 32.25 kHz*/
	CLKPR = (1<<CLKPCE);
	CLKPR = (1<<CLKPS3);

	TCNT2 = 0;// Reset timer 2
	TIMSK2 |= (1<<OCIE2A); // Enable the Output Compare Match A Interrupt.


	set_sleep_mode(SLEEP_MODE_PWR_SAVE);
	sleep_mode();
}

void Exit_Power_Save_Mode(void)
{
	TIMSK2 &= ~(1<<OCIE2A); // Disable the Output Compare Match A Interrupt.

	/* Set the normal operating frequency of 1 MHz */
	CLKPR = (1<<CLKPCE);
	CLKPR = (1<<CLKPS1) | (1<<CLKPS0);

	PRR &= ~(1<<PRSPI); // Enable SPI
	Initialize_SPI(); // reinitalize SPI
}