以下是一个简单的SPI通讯小程序，希望大家能够喜欢。
- // DAC module connections
- sbit DAC_CS at P3_4_bit;
- // End DAC module connections
- unsigned int value;
- // DAC increments (0..4095) --> output voltage (0..Vref)
- void DAC_Output(unsigned int valueDAC) {
- char temp;
- DAC_CS = 0; // select MCP4921
- // Send High Byte
- temp = (valueDAC >> 8) & 0x0F; // Store valueDAC[11..8] to temp[3..0]
- temp |= 0x30; // Define DAC setting http://ww1.microchip.com/downloads/en/DeviceDoc/21897B.pdf#page=18&zoom=100
- SPI1_Write(temp); // Send high byte via SPI
- // Send Low Byte
- temp = valueDAC; // Store valueDAC[7..0] to temp[7..0]
- SPI1_Write(temp); // Send low byte via SPI
- DAC_CS = 1; // deselect MCP4921
- }
- void main() {
- DAC_CS = 1; // deselect MCP4921
- SPI1_Init(); // Initialize SPI module
-
- value = 2048; // When program starts, DAC gives
- // the output in the mid-range
- while (1) { // Endless loop
- if ((!P0_0_bit) && (value < 4095)) { // If P0.0 button is pressed
- value++; // increment value
- }
- else {
- if ((!P0_1_bit) && (value > 0)) { // If P0.1 button is pressed
- value--; // decrement value
- }
- }
-
- DAC_Output(value); // Send value to DAC chip
- Delay_ms(1); // Slow down key repeat pace
-
- }
- }
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