Mikroelektronika MIKROE-742 데이터 시트

This code demonstrates using library routines for Soft_SPI communication. Also, this
example demonstrates working with Microchip's MCP4921 12-bit D/A converter.

program Soft_SPI;

// DAC module connections
var Chip_Select : sbit at PORTB.B0;

SoftSpi_CLK : 

sbit at PORTB.B7;

SoftSpi_SDI : 

sbit at PINB.B6;   // Note: Input signal

SoftSpi_SDO : 

sbit at PORTB.B5;

var Chip_Select_Direction : sbit at DDRB.B0;

SoftSpi_CLK_Direction : 

sbit at DDRB.B7;

SoftSpi_SDI_Direction : 

sbit at DDRB.B6;

SoftSpi_SDO_Direction : 

sbit at DDRB.B5;

// End DAC module connections

var value : word;

procedure InitMain();

DDA0 := 0;                              // Set PA0 pin as input
DDA1 := 0;                              // Set PA1 pin as input

Chip_Select := 1;                     // Deselect DAC

Chip_Select_Direction := 1;              // Set CS# pin as Output

Soft_SPI_Init();                      // Initialize Soft_SPI

// DAC increments (0..4095) --> output voltage (0..Vref)
procedure DAC_Output( valueDAC : word);
var temp : byte;

Chip_Select := 0;                        // Select DAC chip

// Send High Byte

temp := word(valueDAC 

shr 8) and 0x0F;   // Store valueDAC[11..8] to

temp[3..0]

temp := temp 

or 0x30;            // Define DAC setting, see

MCP4921 datasheet

Soft_SPI_Write(temp);           // Send high byte via Soft SPI

// Send Low Byte

temp := valueDAC;                // Store valueDAC[7..0] to temp[7..0]

Soft_SPI_Write(temp);             // Send low byte via Soft SPI

Chip_Select := 1;                        // Deselect DAC chip

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CHAPTER 6