Atmega16 and MAX7219 seven segment display

In this example we connect a MAX7219 seven segment display to our ATmega16, the connection was as follows

VCC → 5V
GND → GND
DIN → PB5
CS → PB0
CLK → PB7

MAX7219 seven segment display

Schematic

Code

sbit Chip_Select at PORTB0_bit;
sbit Chip_Select_Direction at DDB0_bit;

char i;

void max7219_init1() {
Chip_Select = 0;                // Select MAX7219
SPI1_Write(0x09);               // BCD mode for digit decoding
SPI1_Write(0xFF);
Chip_Select = 1;                // Deselect MAX7219

Chip_Select = 0;                // Select MAX7219
SPI1_Write(0x0A);
SPI1_Write(0x0F);               // Segment luminosity intensity
Chip_Select = 1;                // Deselect MAX7219

Chip_Select = 0;                // Select MAX7219
SPI1_Write(0x0B);               // Set scan-limit
SPI1_Write(0x07);               // Display all 8 digits
Chip_Select = 1;                // Deselect MAX7219

Chip_Select = 0;                // Select MAX7219
SPI1_Write(0x0C);               // Set Shutdown register
SPI1_Write(0x01);               // Normal operation
Chip_Select = 1;                // Deselect MAX7219

Chip_Select = 0;                // Select MAX7219
SPI1_Write(0xFF);               // No test
SPI1_Write(0x00);

Chip_Select = 1;                // Deselect MAX7219
}

void main() {

Chip_Select_Direction = 1;      // Set PB0 pin as output
SPI1_Init();                    // Initialize SPI module
max7219_init1();                // Initialize  MAX7219

for (i = 1; i<=8; i++) {
Chip_Select = 0;            // Select MAX7219
SPI1_Write(i);              // Send i to MAX7219 (digit place)
SPI1_Write(8-i);            // Send 8-i to MAX7219 (digit value)
Chip_Select = 1;            // Deselect MAX7219
}
// The result "01234567" is written on the 7-Seg displays
}

Links
MAX7219 CWG 8-Digital Tube Display Module Control Module

MAX7219 Dot Matrix Module Display

5pcs MAX7219 DIP-24 LED Display Driver IC