power.c

#include "config.h"
#ifdef POWER_METER

/* Note that power meter uses an ENC28J60 module which is wrongly wired internally.

See http://www.myplace.nu/mp3/yabbse/index.php?topic=3062.0

Swap wires 3 & 6 in a cable to make this work.
NOT AS PER POST - also needed to swap wires 1 & 2.
(normal cross-over cable switches wires 1 with 3 and 2 with 6
                                    not 1 with 2 and 3 with 6)

Modern hubs will self sense so it doesn't necessarily matter - 
but it risks intermittent faults with different setups 

Syntax is a UDP packet to the meter's port, of form "POWER n" where n is 0 to 5
and represents the ADC to sample.  0=current, 1=voltage (i.e. n/c); 2=current/2

Return is a UDP packet of big-endian 16 bit numbers.  The first = ave current
Remainder are time sequence covering about 8 cycles of the waveform

Fuses: avrdude -p atmega328p -c STK500 -P COM4 -U lfuse:w:0xFF:m -U hfuse:w:0xd9:m -U efuse:w:0xff:m
*/

#include <avr/io.h>
#include <util/delay.h>
#include <stdio.h>
#include <string.h>
#include <avr/interrupt.h>
#include <stdlib.h>
#include "network.h"

#include "power.h"

extern MAC_address myMAC;
extern MergedPacket MashE;
extern IP4_address myIP;

// ----------------------------------------------------------------------------
uint16_t ReadADC(uint8_t channel)
{
uint16_t result;

ADMUX = (AVCC_REF | channel);
ADCSRA |= (1 << ADSC); // Start conversion

while (!(ADCSRA & (1 << ADIF)));  // wait for it

ADCSRA |= (1 << ADIF);  // clear interrupt

result = ADCL; // 8 lowest bits (MUST be read first)
result |= ((uint16_t)ADCH) << 8;

return (result);
}

// --------------------------------------------------------------------------------
void handlePower(uint8_t myADC)
{ // Handle a received Power message request to read a specific ADC
// ADC ranges from 0 to 2.  0 is current; 1 is voltage; 2 is current/2

uint16_t i,tmp;
uint32_t total;
int16_t average;
uint8_t SafeADC;

IP4_address his_IP4;

copyIP4(&his_IP4,&MashE.IP4.source);

SafeADC=(myADC % 6); // 0-5 allowable physically, avoids conflict with other bits

LEDON;

for (i=0;i<(MAX_TIME_SAMPLES);i++)
{
  tmp=ReadADC(SafeADC); // to slow down
  MashE.Power.waveform[i]=tmp;
  tmp=ReadADC(SafeADC); // to slow down
  tmp=ReadADC(SafeADC); // to slow down
}

LEDOFF;

total=0;
for (i=0;i<CYCLE;i++) // Across the 50Hz cycle, get average
  total+=MashE.Power.waveform[i];
average=(int16_t)(0.5+((float)total)/(float)CYCLE); 

total=0;
for (i=0;i<CYCLE;i++) // Divergence from average proportional to current
  total+=abs((int16_t)(MashE.Power.waveform[i])-average); // Safe:spectrum is 10 bit

tmp=(uint16_t)(0.5+((float)total)/(float)CYCLE); // Average divergence

MashE.Power.current=BYTESWAP16(tmp);

#ifdef  LITTLEENDIAN // Although implicit in BYTESWAP, this is faster
for (i=0;i<(MAX_TIME_SAMPLES);i++) // Test MashE.Power.waveform[i]=BYTESWAP16(i*60);
  MashE.Power.waveform[i]=BYTESWAP16(MashE.Power.waveform[i]);
#endif

//launchUDP(&MashE,&his_IP4,POWER_MY_PORT,MashE.UDP.sourcePort,sizeof(MashE.Power),NULL,0);  // Prob OK
launchUDP(&MashE,&his_IP4,POWER_MY_PORT,MashE.UDP.sourcePort,2*(1+MAX_TIME_SAMPLES),NULL,0);

delay_ms(10);
LEDOFF;

return;
}

#endif