MAX1233/MAX1234触摸屏控制器入门

时间：03-17 来源：互联网点击：

T R B1	Read BAT1 result BAT1 _code	0x8005 0x0000
T R B2	Read BAT2 result BAT2_code	0x8006 0x0000
T R A1	Read AUX1 result AUX1 _code	0x8007 0x0000
T R A2	Read AUX2 result AUX2 _code	0x8008 0x0000
T R T1	Read TEMP1 result TEMP1 _code	0x8009 0x0000
T R T2	Read TEMP2 result TEMP2 _code	0x800a 0x0000

3) 触摸屏实例

下面的例子解释了怎样使用DEMO1234.EXE程序来获得触摸屏数据。

3.1) 低成本商用触摸屏

在互联网上搜索"PDA Digitizer/Glasstop"，寻找合适的替代触摸屏。高清触摸屏玻璃的价格范围在50美元至10美元之间，价格取决于型号以及玻璃是否全部贴在显示屏上。

3.2) 连接触摸屏和评估板

MAX1234评估板提供突出插头H5/H6来连接10mm柔性电缆或者长度更短的电缆。H6连接器的间距是0.5mm，比实际触摸屏柔性电缆间距更精细。把柔性电缆插入H6，上锁，选择位于四条柔性电缆中每一电缆中心位置的H5引脚。跳接器连接H5和标有U1的X+、Y+、X-以及Y-测试点。

3.3) 检验触摸屏的连接

第一次连接触摸屏时，通过下面的步骤来验证X和Y连接是否正确。可以有几个触摸屏交叉连接，但大部分不会正常工作。在这些例子中，我们假设X- = left，X+ = right，Y- = top，Y+ = bottom。

表10. 触摸屏物理连接验证命令序列

DEMO1234 Command	Action	SPI data in	Verification
	Connect DVM to X+/GND
T MD	No measurement; drive Y+,Y-	0x0040 0x3701
	Touch top left		X+ = approx. Y-
	Touch top right		X+ = approx. Y-
	Touch bottom left		X+ = approx. Y+
	Touch bottom right		X+ = approx. Y+
	Connect DVM to Y+/GND
T ME	No measurement; drive X+,X-	0x0040 0x3b01
	Touch top left		Y+ = approx. X-
	Touch top right		Y+ = approx. X+
	Touch bottom left		Y+ = approx. X-
	Touch bottom right		Y+ = approx. X+

表11. 纠正触摸屏连接问题

Symptom	Correction
Touch coordinates are mirrored top-to-bottom	Swap the Y+ and Y- connections
Touch coordinates are mirrored left-to-right	Swap the X+ and X- connections
Touch coordinates are rotated 180 degrees	Swap the X+ and X- connections, and swap the Y+ and Y- connections
Touch coordinates are mirrored diagonally	Swap the X+ and Y+ connections, and swap the X- and Y- connections
Touch coordinates do not seem to track, and the distortion is not a simple flip/rotate/mirror transformation	Swap the X+ and Y+ connections; if distortion persists, swap the X+ and Y- connections; if distortion still persists, disconnect touch screen and use DVM to verify X+ to X- resistance and Y+ to Y- resistance; verify with no touch X+ and X- are isolated from Y+ and Y-

3.4) 检测触摸屏的操作：根据需要扫描

在配置MAX1234检测触摸屏操作，根据需要数字化接触屏的位置时，写入寄存器0x40 (ADC控制)，其PENSTS=0，ADSTS=0 (请参考MAX1233/MAX1234数据资料的表6)。读取寄存器0x00 (X轴)后，检测到后续的触摸屏操作时，/PENIRQ信号锁存至低电平，在写入ADC控制寄存器测量X、Y轴之前，保持低电平。

表12. 触摸屏检测命令序列：根据需要扫描

DEMO1234 Command	Action	SPI data in	Verification
T W AC 0b01	Demand scan	0x0040 0x0b01
T R AX	Read conversion result register X	0x8000 0x0000
P R 6	Read PENIRQ-bar pin status		PENIRQ = 1
	Touch the touch screen
P R 6	Read PENIRQ-bar pin status		PENIRQ = 0
T M2	Measure X,Y,Z1,Z2	0x0040 0x0b01 0x8000 0x0000 0x8001 0x0000 0x8002 0x0000 0x8003 0x0000
P R 6	Read PENIRQ-bar pin status		PENIRQ = 1
	Touch and hold the touch screen
P R 6	Read PENIRQ-bar pin status		PENIRQ = 0
T M2	Measure X,Y,Z1,Z2	0x0040 0x0b01 0x8000 0x0000 0x8001 0x0000 0x8002 0x0000 0x8003 0x0000
P R 6	Read PENIRQ-bar pin status		PENIRQ = 0
T M2	Measure X,Y,Z1,Z2	0x0040 0x0b01 0x8000 0x0000 0x8001 0x0000 0x8002 0x0000 0x8003 0x0000
P R 6	Read PENIRQ-bar pin status		PENIRQ = 0
	Release the touch screen
P R 6	Read PENIRQ-bar pin status		PENIRQ = 0
T M2	Measure X,Y,Z1,Z2	0x0040 0x0b01 0x8000 0x0000 0x8001 0x0000 0x8002 0x0000 0x8003 0x0000
P R 6	Read PENIRQ-bar pin status		PENIRQ = 1

3.5) 检测触摸屏操作：自动扫描

在检测触摸屏操作，配置MAX1234，自动数字化触摸屏的接触位置时，写入寄存器0x40 (ADC控制)，其PENSTS=1，ADSTS=0 (请参考MAX1233/MAX1234数据资料的表6)。第一次接触屏幕时，/PENIRQ信号暂时变为低电平，并在读取X寄存器之前不会变化。

表13. 触摸屏检测命令序列：自动扫描

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