GD32F103的IIC模块在进行eeprom读取的时候，当读取的字节数为2时，需要将I2C_CTL0的POAP置为1；POAP的定义如下：
0：ACKEN位决定对当前正在接收的字节发送ACK;
1: ACKEN位决定是否对下一个字节发送ACK.
我的理解时：当读取的字节数为2时，该位置1，表示接收第一个字节后，发送ACK;接收第二个字节后，不发送ACK。这样就能保证时序的正确性。
不知道各位大佬是如何理解的，请赐教。谢谢！
代码如下：
void eeprom_buffer_read(uint8_t* p_buffer, uint8_t read_address, uint16_t number_of_byte)
{
/* wait until I2C bus is idle */
while(i2c_flag_get(I2C0, I2C_FLAG_I2CBSY));
if(2 == number_of_byte)
{
i2c_ackpos_config(I2C0,I2C_ACKPOS_NEXT); //如果接收的的字节数等于2，则将将I2C_CTL0的POAP置为1。
}
/* send a start condition to I2C bus */
i2c_start_on_bus(I2C0);
/* wait until SBSEND bit is set */
while(!i2c_flag_get(I2C0, I2C_FLAG_SBSEND));
/* send slave address to I2C bus */
i2c_master_addressing(I2C0, eeprom_address, I2C_TRANSMITTER);
/* wait until ADDSEND bit is set */
while(!i2c_flag_get(I2C0, I2C_FLAG_ADDSEND));
/* clear the ADDSEND bit */
i2c_flag_clear(I2C0,I2C_FLAG_ADDSEND);
/* wait until the transmit data buffer is empty */
while(SET != i2c_flag_get( I2C0 , I2C_FLAG_TBE));
/* enable I2C0*/
i2c_enable(I2C0);
/* send the EEPROM's internal address to write to */
i2c_data_transmit(I2C0, read_address);
/* wait until BTC bit is set */
while(!i2c_flag_get(I2C0, I2C_FLAG_BTC));
/* send a start condition to I2C bus */
i2c_start_on_bus(I2C0);
/* wait until SBSEND bit is set */
while(!i2c_flag_get(I2C0, I2C_FLAG_SBSEND));
/* send slave address to I2C bus */
i2c_master_addressing(I2C0, eeprom_address, I2C_RECEIVER);
if(number_of_byte < 3){
/* disable acknowledge */
i2c_ack_config(I2C0,I2C_ACK_DISABLE);
}
/* wait until ADDSEND bit is set */
while(!i2c_flag_get(I2C0, I2C_FLAG_ADDSEND));
/* clear the ADDSEND bit */
i2c_flag_clear(I2C0,I2C_FLAG_ADDSEND);
if(1 == number_of_byte){
/* send a stop condition to I2C bus */
i2c_stop_on_bus(I2C0);
}
/* while there is data to be read */
while(number_of_byte){
if(3 == number_of_byte){
/* wait until BTC bit is set */
while(!i2c_flag_get(I2C0, I2C_FLAG_BTC));
/* disable acknowledge */
i2c_ack_config(I2C0,I2C_ACK_DISABLE);
}
if(2 == number_of_byte){
/* wait until BTC bit is set */
while(!i2c_flag_get(I2C0, I2C_FLAG_BTC));
/* send a stop condition to I2C bus */
i2c_stop_on_bus(I2C0);
}
/* wait until the RBNE bit is set and clear it */
if(i2c_flag_get(I2C0, I2C_FLAG_RBNE)){
/* read a byte from the EEPROM */
*p_buffer = i2c_data_receive(I2C0);
/* point to the next location where the byte read will be saved */
p_buffer++;
/* decrement the read bytes counter */
number_of_byte--;
}
}
/* wait until the stop condition is finished */
while(I2C_CTL0(I2C0)&0x0200);
/* enable acknowledge */
i2c_ack_config(I2C0,I2C_ACK_ENABLE);
i2c_ackpos_config(I2C0,I2C_ACKPOS_CURRENT);
}
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