Hello,
I want to communicate Rpi SPI with Atmega1281 hardware SPI module. Rpi is Master configured and Atmega1281 slave. I want to read and write data from Rpi to Atmega1281.
I am using following code on Rpi side.
// spi.c // // Example program for bcm2835 library // Shows how to interface with SPI to transfer a byte to and from an SPI device // // After installing bcm2835, you can build this // with something like: // gcc -o spi spi.c -l bcm2835 // sudo ./spi // // Or you can test it before installing with: // gcc -o spi -I ../../src ../../src/bcm2835.c spi.c // sudo ./spi // // Author: Mike McCauley // Copyright (C) 2012 Mike McCauley // $Id: RF22.h,v 1.21 2012/05/30 01:51:25 mikem Exp $ #include <bcm2835.h> #include <stdio.h> int main(int argc, char **argv) { // If you call this, it will not actually access the GPIO // Use for testing // bcm2835_set_debug(1); if (!bcm2835_init()) { printf("bcm2835_init failed. Are you running as root??\n"); return 1; } if (!bcm2835_spi_begin()) { printf("bcm2835_spi_begin failed. Are you running as root??\n"); return 1; } bcm2835_spi_setBitOrder(BCM2835_SPI_BIT_ORDER_MSBFIRST); // The default bcm2835_spi_setDataMode(BCM2835_SPI_MODE0); // The default bcm2835_spi_setClockDivider(BCM2835_SPI_CLOCK_DIVIDER_65536); // The default bcm2835_spi_chipSelect(BCM2835_SPI_CS0); // The default bcm2835_spi_setChipSelectPolarity(BCM2835_SPI_CS0, LOW); // the default // Send a byte to the slave and simultaneously read a byte back from the slave // If you tie MISO to MOSI, you should read back what was sent uint8_t send_data = 0x31; uint8_t read_data = bcm2835_spi_transfer(send_data); printf("Sent to SPI: 0x%02X. Read back from SPI: 0x%02X.\n", send_data, read_data); if (send_data != read_data) printf("Do you have the loopback from MOSI to MISO connected?\n"); bcm2835_spi_end(); bcm2835_close(); return 0; }
*The Rpi code works loopback *
And the below code is on Atmega1281 Hardware SPI module:
#include <stdio.h> #include <stdlib.h> #include <avr/io.h> #include <util/delay.h> #include "SPI.h" void SPI_Init() { char clear = 0; PRR0 = (1<<PRSPI); DDRB |= 0xF0; SPCR |= 0x00; // SPI slave Mode = 0 DDRB |= (1<<DDB3); // MISO as Output SPCR |= ((1<<SPE)|(1<<SPIE)); // Enable SPI and SPI Interrupt clear = SPDR; clear = SPSR; SREG |= (1<<SREG_I); // Enable Global interrupt } void SPI_write(char val) { char data = 0; SPDR = val; while(!(SPSR & (1<<SPIF))) ; data = SPDR; } char SPI_read() { char value = 0; //SPDR = 0xff; while(!(SPSR & (1<<SPIF))) ; value = SPDR; return value; } void main() { while(1) { value = SPI_read(); SPI_write(value); } }
But i am not getting any data on Rpi side..
Any Help/
Rakesh