avr: port analog input sampling + power calculation and implement gd [get delta] command

mote/v2/avr/ctrl.c

@@ -42,6 +42,8 @@ extern uint8_t phy_to_log[MAX_SENSORS];
 extern volatile struct sensor_struct EEMEM EEPROM_sensor[MAX_SENSORS];
 extern volatile struct sensor_struct sensor[MAX_SENSORS];
 
+extern volatile struct state_struct state[MAX_SENSORS];
+
 void ctrlInit(void)
 {
 	// initialize the CTRL receive buffer
@@ -223,7 +225,7 @@ void ctrlDecode(void)
 void ctrlCmdGet(uint8_t cmd)
 {
 	uint8_t i;
-	uint32_t tmp32;
+	uint32_t tmp32, tmp32_bis;
 
 	switch (cmd) {
 	case 'p':
@@ -254,6 +256,24 @@ void ctrlCmdGet(uint8_t cmd)
 	case 'b':
 		ctrlWriteShortToTxBuffer(event.brown_out);
 		break;
+
+	case 'd':
+		for (i = 0 ; i < MAX_SENSORS; i++) {
+			if (state[i].flags & (STATE_PULSE | STATE_POWER)) {
+				ctrlWriteCharToTxBuffer(i);
+
+				cli();
+				tmp32 = sensor[i].counter;
+				tmp32_bis = (i < 3) ? state[i].power : state[i].timestamp;
+				sei();
+
+				ctrlWriteLongToTxBuffer(tmp32);
+				ctrlWriteLongToTxBuffer(tmp32_bis);
+
+				state[i].flags &= ~(STATE_PULSE | STATE_POWER);
+			}
+		}
+		break;
 	}
 }
 

mote/v2/avr/main.c

@@ -19,6 +19,8 @@
 //
 // $Id$
 
+#include <stdlib.h>
+
 #include <avr/io.h>
 #include <avr/interrupt.h>
 #include <avr/eeprom.h>
@@ -47,6 +49,11 @@ volatile struct sensor_struct sensor[MAX_SENSORS];
 
 volatile struct state_struct state[MAX_SENSORS];
 
+volatile uint8_t muxn = 0;
+volatile uint16_t timer = 0;
+
+volatile struct time_struct time = {0, 0};
+
 ISR(SPI_STC_vect)
 {
 	uint8_t spi_rx, rx, tx; 
@@ -140,7 +147,39 @@ ISR(SPI_STC_vect)
 
 ISR(TIMER1_COMPA_vect)
 {
-	/* void */
+	uint8_t muxn_l = phy_to_log[muxn];
+	
+	MacU16X16to32(state[muxn_l].nano, sensor[muxn_l].meterconst, ADC);
+
+	if (state[muxn_l].nano > WATT) {
+		sensor[muxn_l].counter++;
+
+		state[muxn_l].flags |= STATE_PULSE;
+		state[muxn_l].nano -= WATT;
+		state[muxn_l].pulse_count++;
+	}
+
+	if ((timer == SECOND) && (muxn == muxn_l)) {
+		state[muxn].nano_start = state[muxn].nano_end;
+		state[muxn].nano_end = state[muxn].nano;
+		state[muxn].pulse_count_final = state[muxn].pulse_count;
+		state[muxn].pulse_count = 0;
+		state[muxn].flags |= STATE_POWER_CALC;
+	}
+
+	/* Cycle through the available ADC input channels (0/1/2). */
+	muxn++;
+	if (!(muxn %= 3)) timer++;
+	if (timer > SECOND) timer = 0;
+
+	/* In order to map this to 1000Hz (=ms) we have to skip every second interrupt. */
+	if (!time.skip) time.ms++ ;
+	time.skip ^= 1;
+
+	ADMUX &= 0xF8;
+	ADMUX |= muxn;
+	/* Start a new ADC conversion. */
+	ADCSRA |= (1<<ADSC);
 }
 
 ISR(ANALOG_COMP_vect)
@@ -216,8 +255,43 @@ void setup_analog_comparator(void)
 	ACSR |= (1<<ACBG) | (1<<ACIE) | (1<<ACIS1) | (1<<ACIS0);
 }
 
+void calculate_power(struct state_struct *pstate)
+{
+	int32_t rest, power = 0;
+	uint8_t pulse_count;
+
+	cli();
+	rest = pstate->nano_end - pstate->nano_start;
+	pulse_count = pstate->pulse_count_final;
+	sei();
+
+	// Since the AVR has no dedicated floating-point hardware, we need 
+	// to resort to fixed-point calculations for converting nWh/s to W.
+	// 1W = 10^6/3.6 nWh/s
+	// value[watt] = 3.6/10^6 * rest[nWh/s]
+	// value[watt] = 3.6/10^6 * 65536 * (rest[nWh/s] / 65536)
+	// value[watt] = 3.6/10^6 * 65536 * 262144 / 262144 * (rest[nWh/s] / 65536)
+	// value[watt] = 61847.53 / 262144 * (rest[nWh/s] / 65536)
+	// We round the constant down to 61847 to prevent 'underflow' in the
+	// consecutive else statement.
+	// The error introduced in the fixed-point rounding equals 8.6*10^-6.
+	MacU16X16to32(power, (uint16_t)(labs(rest)/65536), 61847);
+	power /= 262144;
+
+	if (rest >= 0) {
+		power += pulse_count*3600;
+	}
+	else {
+		power = pulse_count*3600 - power;
+	}
+
+	pstate->power = power;
+}
+
 int main(void)
 {
+	uint8_t i;
+
 	// RS-485: Configure PD5=DE as output pin with low as default
 	DDRD |= (1<<DDD5);
 	// set high to transmit
@@ -242,7 +316,15 @@ int main(void)
 			ctrlDecode();
 			spi_status &= ~SPI_NEW_CTRL_MSG;
 		}
-		
+
+		for (i = 0; i < 3; i++) {
+			if (state[i].flags & STATE_POWER_CALC) {
+				calculate_power((struct state_struct *)&state[i]);
+				state[i].flags &= ~STATE_POWER_CALC;
+				state[i].flags |= STATE_POWER;
+			}
+		}
+
 		// toggle the LED=PB0 pin
 		_delay_ms(50);
 		 DDRB ^= (1<<PB0);

mote/v2/avr/main.h

@@ -21,9 +21,13 @@ struct sensor_struct {
 	uint16_t meterconst;
 };
 
-#define STATE_PULSE  = 1
+# define WATT 1000000000
-#define STATE_TOGGLE = 2
+# define SECOND 666 // 667Hz - 1
-#define STATE_POWER  = 4
+
+#define STATE_PULSE		1
+#define STATE_SKIP		2
+#define STATE_POWER_CALC	4
+#define STATE_POWER		8
 
 struct state_struct {
 	uint8_t  flags;
@@ -38,6 +42,11 @@ struct state_struct {
 	uint32_t timestamp;
 };
 
+struct time_struct {
+	uint8_t	 skip;
+	uint32_t ms;
+};
+
 /* 
  * This macro performs a 16x16 -> 32 unsigned MAC in 37 cycles with operands and results in memory
  * based on http://www2.ife.ee.ethz.ch/~roggend/publications/wear/DSPMic_v1.1.pdf par 3.4 and table 31.

mote/v2/avr/makefile

@@ -123,7 +123,7 @@ CDEFS += -DUART_DEFAULT_BAUD_RATE=115200
 
 # override default CTRL buffer sizes
 CDEFS += -DCTRL_RX_BUFFER_SIZE=32
-CDEFS += -DCTRL_TX_BUFFER_SIZE=32
+CDEFS += -DCTRL_TX_BUFFER_SIZE=128
 
 # Place -I options here
 CINCS =