/*
* Project name : Demo5_7a : spi - 7 segments display
* Author : Avans-TI, WvdE, JW
* Revision History : 20110228: - initial release; 20120307: - this version
* Description : This program sends data to a 4-digit display with spi
* Test configuration:
 MCU: ATmega128
 Dev.Board: BIGAVR6
 Oscillator: External Clock 08.0000 MHz
 Ext. Modules: Serial 7-seg display
 SW: AVR-GCC
* NOTES : Turn ON switch 15, PB1/PB2/PB3 to MISO/MOSI/SCK
*/
#define F_CPU 10e6
#include <avr/io.h>
#include <util/delay.h>
#define BIT(x) ( 1<<x )
#define DDR_SPI DDRB // spi Data direction register
#define PORT_SPI PORTB // spi Output register
#define SPI_SCK 1 // PB1: spi Pin System Clock
#define SPI_MOSI 2 // PB2: spi Pin MOSI
#define SPI_MISO 3 // PB3: spi Pin MISO
#define SPI_SS 0 // PB0: spi Pin Slave Select
// wait(): busy waiting for 'ms' millisecond - used library: util/delay.h
void wait(int ms)
{
for (int i=0; i<ms; i++)
_delay_ms(1);
}
void spi_masterInit(void)
{

DDR_SPI = 0xff; // All pins output: MOSI, SCK, SS, SS_display
DDR_SPI &= ~BIT(SPI_MISO); // except: MISO input
PORT_SPI |= BIT(SPI_SS); // SS_ADC == 1: deselect slave
SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR1); // or: SPCR = 0b11010010;
// Enable spi, MasterMode, Clock rate fck/64
// bitrate=125kHz, Mode = 0: CPOL=0, CPPH=0
}
// Write a byte from master to slave
void spi_write( unsigned char data )
{
SPDR = data; // Load byte --> starts transmission
while( !(SPSR & BIT(SPIF)) ); // Wait for transmission complete
}
// Write a byte from master to slave and read a byte from slave - not used here
char spi_writeRead( unsigned char data )
{
SPDR = data; // Load byte --> starts transmission
while( !(SPSR & BIT(SPIF)) ); // Wait for transmission complete
data = SPDR; // New received data (eventually, MISO) in SPDR
return data; // Return received byte
}
// Select device on pinnumer PORTB
void spi_slaveSelect(unsigned char chipNumber)
{
PORTB &= ~BIT(chipNumber);
}
// Deselect device on pinnumer PORTB
void spi_slaveDeSelect(unsigned char chipNumber)
{
PORTB |= BIT(chipNumber);
}

void spi_writeCommand(unsigned char adress, unsigned char data)
{
spi_slaveSelect(0);
spi_write(adress);
spi_write(data);
spi_slaveDeSelect(0);
}

// Initialize the driver chip (type MAX 7219)
void displayDriverInit()
{
spi_slaveSelect(0); // Select display chip (MAX7219)
 spi_write(0x09); // Register 09: Decode Mode
 spi_write(0xFF); // -> 1's = BCD mode for all digits
 spi_slaveDeSelect(0); // Deselect display chip
 spi_slaveSelect(0); // Select dispaly chip
 spi_write(0x0A); // Register 0A: Intensity
 spi_write(0x04); // ->the hex value here selects the intensity (in range [1..F])
 spi_slaveDeSelect(0); // Deselect display chip
 spi_slaveSelect(0); // Select display chip
 spi_write(0x0B); // Register 0B: Scan-limit
 spi_write(0x03); // -> 1 = Display digits 0..1 the hex value here selects how many segments get initialized
 spi_slaveDeSelect(0); // Deselect display chip
 spi_slaveSelect(0); // Select display chip
 spi_write(0x0C); // Register 0B: Shutdown register
 spi_write(0x01); // -> 1 = Normal operation
 spi_slaveDeSelect(0); // Deselect display chip
}
// Set display on ('normal operation')
void displayOn()
{
 spi_slaveSelect(0); // Select display chip
 spi_write(0x0C); // Register 0B: Shutdown register
 spi_write(0x01); // -> 1 = Normal operation
 spi_slaveDeSelect(0); // Deselect display chip
}
// Set display off ('shut down')
void displayOff()
{
 spi_slaveSelect(0); // Select display chip
 spi_write(0x0C); // Register 0B: Shutdown register
 spi_write(0x00); // -> 1 = Normal operation
 spi_slaveDeSelect(0); // Deselect display chip
}
int main()
{
DDRB=0x01; // Set PB0 pin as output for display select
spi_masterInit(); // Initialize spi module
displayDriverInit(); // Initialize display chip
// clear display (all zero's)
for (unsigned char i =1; i<=4; i++)
{
// spi_slaveSelect(0); // Select display chip
 //spi_write(i); // digit adress: (digit place)
 //spi_write(0); // digit value: 0
 //spi_slaveDeSelect(0); // Deselect display chip
spi_writeCommand(i,i);
}
wait(1000);
// write 4-digit data
for (unsigned char i =1; i<=4; i++)
 {
//spi_slaveSelect(0); // Select display chip
//spi_write(i); // digit adress: (digit place)
//spi_write(i); // digit value: i (= digit place)
//spi_slaveDeSelect(0); // Deselect display chip
spi_writeCommand(i,i);
wait(1000);
 }
wait(1000);
 return (1);
}