司生产的一种低功耗的电压输出型10位串行D/A转换器，兼容SPI接口，MAX515固定增益为2，用+5V单电源工作。本例运行时，通过调节RV1向单片机输入模拟电压，单片机将A/D转换后的数字量输出给MAX515，经D/A转换后所输出的 模拟电压控制LED亮度变化
Proteus仿真截图：
Ateml Studio6.2 编译通过截图：
程序清单：
- /*
- * GccApplication34.c
- *
- * Created: 2014-12-15 21:07:48
- * Author: Administrator
- */
- #define F_CPU 4000000UL
- #include <avr/io.h>
- #include <util/delay.h>
- #include <stdint.h>
- #define SPI_EN() (PORTB &=~_BV(PB4))
- #define SPI_DI() (PORTB |= _BV(PB4))
- void SPI_MasterInit()
- {
- DDRB = 0B10110000;PORTB = 0xFF;
- SPCR |= _BV(SPE)|_BV(MSTR)|_BV(SPR0);
- }
- uint8_t SPI_Transmit(uint8_t d)
- {
- SPDR = d;
- while(!(SPSR & _BV(SPIF)));
- SPSR |= _BV(SPIF);
- return SPDR;
- }
- uint16_t ADC_Convert(uint8_t CH)
- {
- ADMUX = CH;
- return ADC;
- }
- int main(void)
- {
- uint16_t dat;
- DDRA = 0x00;
- SPI_MasterInit();
- ADCSRA = 0xE6;
- _delay_ms(3000);
- while(1)
- {
- //TODO:: Please write your application code
- dat = ADC_Convert(4);
- dat <<=2;
- SPI_EN();
- SPI_Transmit(dat>>8);
- SPI_Transmit(dat);
- SPI_DI();
- _delay_ms(100);
- }
- }
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