门限滞回设置的C程序代码

将接近检测传感器集成到系统后，一个经常遇到的问题是如何正确选择接近检测的门限，以便在用户通话期间打开或关闭屏幕。门限设置须确保出现错误判断的几率非常低，而且能够支持绝大多数使用者的情况。
门限滞回例程

#define MAX44000_ADDR	0x94#define INT_STATUS_REG	0x00#define OFF_THRESHOLD	4600#define OFF_DELAY		1#define ON_THRESHOLD	4000#define ON_DELAY		3uint8 screenStatus;	// 0 means off, 1 means on/*i2cWriteBytes()Arguments:uint8 address - device addressuint8 start_reg - register where the first byte is writtenuint8 *data - data to writeuint8 nbytes - number of bytes to writeConsecutively writes several bytes to some i2c device starting at some specified address -- implemented elsewhere*/void i2cWriteBytes(uint8 address,uint8 start_reg,uint8 *data,uint8 nbytes);/*MAX44000InterruptHandler()

以下代码用于实现MAX44000 INT引脚的中断处理，假设MAX44000的接近检测传感器设置为14位模式，并已使能中断。此外，假设屏幕状态初始化为1或0，详细信息请参阅数据资料的寄存器说明部分。

*/void MAX44000InterruptHandler() {uint8 i2cData[3];i2cRead1Byte(MAX44000_ADDR,INT_STATUS_REG,i2cData);if (i2cData0x01 != 0)return;	// check to make sure interrupt really fired// this simultaneously clears the interrupt flagif (screenStatus) {i2cData[0] = ON_DELAY;	i2cData[1] = ON_THRESHOLD >> 8  0xBF; // set ABOVE = 0i2cData[2] = ON_THRESHOLD  0xFF;} else {i2cData[0] = OFF_DELAY;	 i2cData[1] = OFF_THRESHOLD >> 8 | 0x40; // set ABOVE = 1i2cData[2] = OFF_THRESHOLD  0xFF;} // set the new threshold depending on what the screen status was// set the delay and threshold after each interrupti2cWriteBytes(MAX44000_ADDR,0x0A,i2cData,3);return;} // MAX44000InterruptHandler