觸控設備手勢喚醒的設計思路及其實現

　　// this handles hardware-level interrupts on the micro

　　__interrupt void irq_handler（ void ）

　　{

　　...

　　// if the hardware interrupt came from the MAX44000 sensor

　　// pulling its INT pin low

　　if （ irq_source == MAX44000 ）

　　{

　　// if the device is in sleep mode

　　if （device_status == SLEEP_MODE）

　　{

　　device_status = WAKE_MODE; // wake up the device

　　...

　　// reconfigure whatever else you need here as the system wakes up

　　}

　　// otherwise， handle it however it is you wish

　　else

　　{

　　...

　　}

　　}

　　...

　　}

　　/**

　　* configure_max44000_for_sleep_mode（）

　　*

　　* Sets up the MAX44000 to trigger a hardware interrupt when the proximity

　　* counts go above some set threshold.

　　*

　　* Arguments：

　　* uint8 upper_threshold - the set threshold （8-bit mode）

　　*

　　* Returns：

　　* n/a

　　*/

　　void configure_max44000_for_sleep_mode（uint8 upper_threshold）

　　{

　　uint8 max44000_thresh_registers［］ = {0x0B，0x0C};

　　uint8 max44000_upper_thresh［］ = {0x40，0};

　　max44000_upper_thresh［1］ = upper_threshold;

　　// do a consecutive write of 0 followed by upper_threshold to

　　// registers 0xB and 0xC， respectively

　　// MAX44000_ADDR is usually 0x94

　　// interrupt will trigger only if proximity value is above the threshold

　　write_i2c_register（MAX44000_ADDR，max44000_thresh_registers，

　　max44000_upper_thresh，2）;

　　// write to bits 2 and 3 of register 0x0A here if you wish to set the

　　// persist time to anything other than one sample

　　// writes to register 0x01 to enable interrupts on the MAX44000

　　max44000_enable_interrupt（）;

　　return;

　　}