我正在使用Arduino mega 2560和光传感器BH1750FVI。要显示结果我正在使用minicom,请在Ubuntu 16.04 LTS上工作
我写代码,它的工作,并从光传感器向我发送数据结果读取,我只能读取一次信息。我不明白如何通过中断(TWI_vect)使它工作,并且每次使用uart时都显示结果。
#include "my_header.h"
#define I2C_STATUS_MASK 0xF8
#define START_COND_TRANSMITTED 0x08
#define REPEATED_START_COND_TRANSMITTED 0x10
#define SLA_W_TRANSMITTED_ACK_RECEIVED 0x18
#define DATA_TRANSMITTED_ACK_RECEIVED 0x28
#define SLA_R_TRANSMITTED_ACK_RECEIVED 0x40
#define DATA_RECEIVED_ACK_RETURNED 0x50
#define DATA_RECEIVED_NACK_RETURNED 0x58
volatile int light_intensity = 0; // var for read data from sensor
ISR(USART0_UDRE_vect) {
if (!bufferIsEmpty(&buffer)) //if we have something to read do it
UDR0 = popFromBuff(&buffer);
else
UCSR0B &= ~_BV(UDRIE0); //disallow interrupts
}
int main(void) {
cli();
init_port(); //initialize my port
init_buffer(&buffer, BUFF_SIZE); //init ring_buffer for uart
init_uart();
TWI_init();
sei();
TWI_start(); //send start
TWI_send_SLA(WRITE); //send SLA+W to light sensor
TWI_sendData(0b00010000); //opecode for Measurement
TWI_stop(); //stop
TWI_start(); //send start
TWI_send_SLA(READ); // send SLA+R to sensor
TWI_readData(); // read data from it light_intensity = TWDR
TWI_stop(); // stop
u_printnumbers(light_intensity); /*my func that send data to ring_buffer and later
*using interrupts send it form buffer to UDR
*/
u_print("\n");
while (1) {
if (!bufferIsEmpty(&buffer)) /*if buffer is not empty allow interrupts for uart*/
UCSR0B |= _BV(UDRIE0);
}
}
所以这段代码有效,我从传感器接收数据,一切正常。但是我想将其与中断(TWI_vect)一起使用,并始终像while()一样从传感器接收数据。我读了很多信息,但不明白它的外观。
您能通过一些示例向我展示使用我的代码与中断(TWI_vect)的正确方法。谢谢!
最佳答案
要使用中断驱动的双向电源接口(I²C; TWI),必须在TWI ISR内部实现某种状态机。
Atmel Application Note AVR135简要说明如何完成此操作。您将必须准备好缓冲区,并将事务抽象为某种结构。例如,您可以
struct i2c_transfer {
uint8_t i2c_sla; /* slave address */
const uint8_t *txbuf;
size_t txbytes;
uint8_t *rxbuf;
size_t rxbytes;
}
设置好之后,便有一个功能开始传输I2C,并通过检查
txbytes == 0 && rxbytes == 0
还是发生错误来检查是否完成。然后,您的ISR需要检查其状态,并根据应写入和读取的字节数采取适当的措施。