| /* # I2C代码片段说明 | |
| 1. 本文件夹中提供的驱动代码供参赛选手完成程序设计参考。 | |
| 2. 参赛选手可以自行编写相关代码或以该代码为基础，根据所选单片机类型、运行速度和试题 | |
| 中对单片机时钟频率的要求，进行代码调试和修改。 | |
| */ | |
| // | |
| static void I2C_Delay(unsigned char n) | |
| { | |
| do | |
| { | |
| _nop_();_nop_();_nop_();_nop_();_nop_(); | |
| _nop_();_nop_();_nop_();_nop_();_nop_(); | |
| _nop_();_nop_();_nop_();_nop_();_nop_(); | |
| } | |
| while(n--); | |
| } | |
| // | |
| void I2CStart(void) | |
| { | |
| sda = 1; | |
| scl = 1; | |
| I2C_Delay(DELAY_TIME); | |
| sda = 0; | |
| I2C_Delay(DELAY_TIME); | |
| scl = 0; | |
| } | |
| // | |
| void I2CStop(void) | |
| { | |
| sda = 0; | |
| scl = 1; | |
| I2C_Delay(DELAY_TIME); | |
| sda = 1; | |
| I2C_Delay(DELAY_TIME); | |
| } | |
| // | |
| void I2CSendByte(unsigned char byt) | |
| { | |
| unsigned char i; | |
| for(i=0; i<8; i++){ | |
| scl = 0; | |
| I2C_Delay(DELAY_TIME); | |
| if(byt & 0x80){ | |
| sda = 1; | |
| } | |
| else{ | |
| sda = 0; | |
| } | |
| I2C_Delay(DELAY_TIME); | |
| scl = 1; | |
| byt <<= 1; | |
| I2C_Delay(DELAY_TIME); | |
| } | |
| scl = 0; | |
| } | |
| // | |
| unsigned char I2CReceiveByte(void) | |
| { | |
| unsigned char da; | |
| unsigned char i; | |
| for(i=0;i<8;i++){ | |
| scl = 1; | |
| I2C_Delay(DELAY_TIME); | |
| da <<= 1; | |
| if(sda) | |
| da |= 0x01; | |
| scl = 0; | |
| I2C_Delay(DELAY_TIME); | |
| } | |
| return da; | |
| } | |
| // | |
| unsigned char I2CWaitAck(void) | |
| { | |
| unsigned char ackbit; | |
| scl = 1; | |
| I2C_Delay(DELAY_TIME); | |
| ackbit = sda; | |
| scl = 0; | |
| I2C_Delay(DELAY_TIME); | |
| return ackbit; | |
| } | |
| // | |
| void I2CSendAck(unsigned char ackbit) | |
| { | |
| scl = 0; | |
| sda = ackbit; | |
| I2C_Delay(DELAY_TIME); | |
| scl = 1; | |
| I2C_Delay(DELAY_TIME); | |
| scl = 0; | |
| sda = 1; | |
| I2C_Delay(DELAY_TIME); | |
| } | |
| unsigned char Read_Pcf8591(unsigned char contrl) | |
| { | |
| unsigned char dd; | |
| I2CStart(); | |
| I2CSendByte(0x90); | |
| I2CWaitAck(); | |
| I2CSendByte(contrl); | |
| I2CWaitAck(); | |
| I2CStart(); | |
| I2CSendByte(0x91); | |
| I2CWaitAck(); | |
| dd=I2CReceiveByte(); | |
| I2CSendAck(1); | |
| I2CStop(); | |
| return dd; | |
| } | |