MAX1233/MAX1234触摸屏控制器入门

时间：03-17 来源：互联网点击：

表5. 外部基准命令

DEMO1234 Command	Action	SPI data in
T W AC 0300	External reference must be provided; ADC_control_wr_demand_scan:(write)demand scan ADC_control_AD0000:configure reference ADC_control_RES11:external reference	0x0040 0x0300

2.3) 测量外部电压输入AUX1和AUX2

表6. ADC测量命令序列

DEMO1234 Command	Action (Triggered by A/D3210 Bits)	SPI data in
T M8	Measure AUX1 with 12-bit resolution and 3.5μs conversion rate	0x0040 0x2301 0x8007 0x0000
T W AC 2301	Trigger ADC scan of AUX1; ADC control word 0x2301 means: ADC_control_wr_demand_scan ADC_control_AD1000 /* measure AUX1 / ADC_control_RES11 / 12-bit resolution / ADC_control_AVG00 / no averaging / ADC_control_CNR00 / conversion rate 3.5μs / ADC_control_RFV / RFV=1: VREF=2.5V */	0x0040 0x2301
T R A1	Read AUX1 result AUX1_code	0x8007 0x0000
T M9	Measure AUX2 with 12-bit resolution and 3.5μs conversion rate	0x0040 0x2701 0x8008 0x0000

2.4) 将AUX1和AUX2转换结果译为物理值

下面的C/C++伪代码片断总结了DEMO1234程序是怎样解释AUX1和AUX2转换结果的。

    /* ADC control resolution value selects num_codes 4096 (12-bit), 1024 (10-bit), or 256 (8-bit) */int num_codes = 4096; /* ADC_control_RES11: 12-bit resolution *//* Voltage that corresponds to the full-scale ADC code; may be internal 1V or 2.5V ref, or ext ref. */double ADC_fullscale_voltage = 2.5; /* ADC_control_RFV=1: VREF=2.5V.  RFV=0: VREF=1.0V. *//* AUX1_code is the 16-bit result read by SPI command 0x8007 */double AUX1_Voltage = (AUX1_code * ADC_fullscale_voltage) / num_codes;/* AUX2_code is the 16-bit result read by SPI command 0x8008 */double AUX2_Voltage = (AUX2_code * ADC_fullscale_voltage) / num_codes;

2.5) 测量外部电压输入BAT1和BAT2

表7. ADC测量命令序列

DEMO1234 Command	Action (Triggered by A/D3210 Bits)	SPI data in
T M6	Measure BAT1 with 12-bit resolution and 3.5μs conversion rate	0x0040 0x1b01 0x8005 0x0000
T W AC 1b01	Trigger ADC scan of BAT1; ADC control word 0x1b01 means: ADC_control_wr_demand_scan ADC_control_AD0110 /* measure BAT1 / ADC_control_RES11 / 12-bit resolution / ADC_control_AVG00 / no averaging / ADC_control_CNR00 / conversion rate 3.5μs / ADC_control_RFV / RFV=1: VREF=2.5V */	0x0040 0x1b01
T R B1	Read BAT1 result BAT1_code	0x8005 0x0000
T W AC 1b21	Trigger ADC scan of BAT1; ADC control word 0x1b21 means: ADC_control_wr_demand_scan ADC_control_AD0110 /* measure BAT1 / ADC_control_RES11 / 12-bit resolution / ADC_control_AVG00 / no averaging / ADC_control_CNR10 / conversion rate 10μs / ADC_control_RFV / RFV=1: VREF=2.5V */	0x0040 0x1b21
T R B1	Read BAT1 result BAT1_code	0x8005 0x0000
T M7	Measure BAT2 with 12-bit resolution and 3.5μs conversion rate	0x0040 0x1f01 0x8006 0x0000

2.6) 将BAT1和BAT2转换结果译为物理值

下面的C/C++伪代码片断总结了DEMO1234程序是怎样解释BAT1和BAT2转换结果的。注意：通过一个4:1输入分配器来测量BAT1和BAT2。

    /* ADC control resolution value selects num_codes 4096 (12-bit), 1024 (10-bit), or 256 (8-bit) */int num_codes = 4096; /* ADC_control_RES11: 12-bit resolution *//* Voltage that corresponds to the full-scale ADC code; may be internal 1V or 2.5V ref, or ext ref. */double ADC_fullscale_voltage = 2.5; /* ADC_control_RFV=1: VREF=2.5V.  RFV=0: VREF=1.0V. *//* Note: BAT1 and BAT2 measure through a 4:1 input divider. *//* BAT1_code is the 16-bit result read by SPI command 0x8005 */double BAT1_Voltage = 4 * (BAT1_code * ADC_fullscale_voltage) / num_codes;/* BAT2_code is the 16-bit result read by SPI command 0x8006 */double BAT2_Voltage = 4 * (BAT2_code * ADC_fullscale_voltage) / num_codes;

2.7) 测量内部温度TEMP1和TEMP2

表8. ADC测量命令序列

DEMO1234 Command

Action (Triggered by A/D3210 Bits)

SPI data in

T MA

Measure TEMP1 with 12-bit resolution and 3.5μs conversion rate

0x0040 0x2b01

0x8009 0x0000

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