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Power Monitoring with ADE7756 or similar.

 
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gomond



Joined: 05 Nov 2008
Posts: 18

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Power Monitoring with ADE7756 or similar.
PostPosted: Tue Oct 13, 2009 2:12 am     Reply with quote
Hi
I am building a Data Logger, with an 18f8722, SD-Card... and ADE7756 Energy metering IC (SPI interface).
And I was wondering if anyone had ay experience in this area, as I am a little green.

I have hooked it all up and I have the basic datalogger running like a ripper (thanks to Andrew Smallridge from Brush Electronics).

And now I just have to work out how to get the power metering done.

I was thinking of doing it using a couple of diffferential ADC's originally, but this looks quicker, though maybe less flexible.

I was wondering if anyone had already written a CCS driver for this IC?

Before I attempt to reinvent the wheel.

Thanks

Greg.
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Wed Oct 14, 2009 4:41 pm     Reply with quote
This Microchip ASM code could be converted to CCS:
http://www.analog.com/static/imported-files/application_notes/317740795RMS_CODE.txt
Converting it to use CCS functions would greatly reduce the number of
lines of code. Here's an example:

I have converted the SPIRX and ENGREAD1 functions to CCS.
I didn't try to improve it very much. They use globals to transfer
data. For simplicity, I just kept it that way. That could be improved.
Compare this code to the ASM code in the link. But remember,
I don't want to do this project for you. This is just an example to
help you to see how to convert the code in a minimal way. You must
do the rest of it, if you want to.
Code:

#include <16F877.H>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7,ERRORS)

// SPI mode constants used in the setup_spi() function.
#define SPI_MODE_0  (SPI_L_TO_H | SPI_XMIT_L_TO_H)
#define SPI_MODE_1  (SPI_L_TO_H)
#define SPI_MODE_2  (SPI_H_TO_L)
#define SPI_MODE_3  (SPI_H_TO_L | SPI_XMIT_L_TO_H)


#define ADE7756_CS  PIN_B4

#define RSTENERGY_CMD  0x03

int8 insd5;
int8 insd4;
int8 insd3;
int8 insd2;
int8 insd1;

//--------------------------
void SPIRX(int8 spi_command, int8 wordlen)
{
output_low(ADE7756_CS);

spi_write(spi_command);

insd1 = 0;
insd2 = 0;
insd3 = 0;
insd4 = 0;
insd5 = 0;

// This switch-case code intentionally leaves out the break
// statements, because it is intended to "fall through" to
// get all the required bytes (from 1 to 5, depending on
// the parameter passed to the SPIRX() function).
switch(wordlen)
  {
   case 5:
     insd5 = spi_read(0);
   case 4:
     insd4 = spi_read(0);
   case 3:
     insd3 = spi_read(0);
   case 2:
     insd2 = spi_read(0);
   case 1:
     insd1 = spi_read(0);
     break;
   default:
     printf("Error: Incorrect wordlen\n\r");
   
   }

output_high(ADE7756_CS);
}

//---------------------------
void ENGREAD1(void)
{
SPIRX(RSTENERGY_CMD, 5);     // 40 bits = 5 bytes
}

//============================   
void main()
{
// The ADE7756 will be connected to the 3 hardware SPI pins
// on the PIC.   A spare i/o pin is used for the Chip Select.
// The max allowable SCLK is 3 MHz, so a divisor of 4 is used
// with our 4 MHz crystal, to give 1 MHz SCLK.
setup_spi(SPI_MASTER | SPI_MODE_1 | SPI_CLK_DIV_4); 

output_high(ADE7756_CS);
delay_ms(10);

ENGREAD1();

// The result from the ENGREAD1() function is returned in
// 5 global variables.  Display them.
printf("%x %x %x %x %x \n\r" insd5, insd4, insd3, insd2, insd1);

while(1);
}


---

Edit: Fixed a problem where I left ADE7756_CS in a low state
at the end of SPIRX(). Also added code to initialize it to a high
level at the start of main() and do a short delay after that.


Last edited by PCM programmer on Thu Oct 15, 2009 5:30 pm; edited 1 time in total
gomond



Joined: 05 Nov 2008
Posts: 18

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PostPosted: Thu Oct 15, 2009 3:13 am     Reply with quote
Quote:


This Microchip ASM code could be converted to CCS:
http://www.analog.com/static/imported-files/application_notes/317740795RMS_CODE.txt
Converting it to use CCS functions would greatly reduce the number of
lines of code. Here's an example:

I have converted the SPIRX and ENGREAD1 functions to CCS.
I didn't try to improve it very much. They use globals to transfer
data. For simplicity, I just kept it that way. That could be improved.
Compare this code to the ASM code in the link. But remember,
I don't want to do this project for you. This is just an example to
help you to see how to convert the code in a minimal way. You must
do the rest of it, if you want to.


Thanks Heaps PCM Programmer

That is a ripper kick start. I would have never thought that it could be simpilfied like that.

Being a fitter and turner this stuff takes a while to convert to nuts and bolts but with help like this I can at least get my head arround it.

Thanks again.

Greg.
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