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sani
Joined: 24 Nov 2010 Posts: 1
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SPI communication for PIC18f46 |
Posted: Wed Nov 24, 2010 8:59 am |
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Hi all,
I'm currently working on two PIC18f46k20 and to get two of them connected using SPI master/slave method. I'm using the MPLab compiler and built with the example code from the website but it doesn't seem to work. There is something to do the the '#fuses' definition. Can anyone tell me how to get it sorted. Appreciate it alot, thanks.
Here is the code for the master.
Code: |
#include <18f4520.h>
#fuses EC,NOLVP,NOWDT,NOPROTECT
#device ADC=8
#use delay(clock=40000000)
//These define the different SPI modes in terms of constants the compiler knows about
//NOTE: our PICs only seemed to work in modes 1 and 3, though they are supposed to work with any modes
#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 SS_PIN PIN_D0 //this can be any output pin on the master
void main()
{
int val;
//Set up the ADC to read from A0
setup_adc_ports(AN0);
setup_adc(ADC_CLOCK_INTERNAL);
set_adc_channel(0);
//The next statement sets up the SPI hardware, with this PIC as a master using mode 1
//SPI_CLK_DIV_64 sets the speed of the SPI clock pulses--this is the slowest speed
setup_spi(SPI_MASTER | SPI_MODE_1 | SPI_CLK_DIV_64);
while(true) {
val = read_adc(); //read the value to be sent
output_low(SS_PIN); //pull the slave select line low to select the slave
delay_us(10); //give the slave time to notice this (may be unnecessary)
spi_write(val); //send the value
delay_us(10); //(may be unnecessary)
output_high(SS_PIN); //deselect the slave.
delay_ms(10);
}
}
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PCM programmer
Joined: 06 Sep 2003 Posts: 21708
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Posted: Wed Nov 24, 2010 12:39 pm |
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Quote: | #include <18f4520.h>
#fuses INTRC_IO,NOLVP,NOWDT,NOPROTECT
#device ADC=8
#use delay(clock=4000000) |
The changes shown in bold above will allow the PIC to run.
The oscillator is changed to Internal, and the clock is changed to 4 MHz.
Make both those changes, re-compile, and then you can start to test
the program. |
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