【TI 测评】TI-MSP432P401R LanchPad评测（二）ADC采样加速度传感器MMA7361

    这几天尝试玩了一下MSP432P401R的ADC采样外设。MSP432P401R这款单片机的ADC是14位精度，通过软件过采样可以支持达到16位精度，高达1Msps采样速率。有单端和差分方式输入，2个窗口比较器，有32个采样通道，其中内部通道6个。有3个内部电压基准：1.2V，1.45V，2.5V。

   下图是ADC框图：

    正好自己有用模拟型加速度传感器MMA7361，以前项目做震动和倾斜检测用的。这次正好拿来测试一下MSP432P401R的ADC功能。MMA7361有XYZ轴模拟电压，需要3路AD采样。

硬件连接：
Z轴—>P5.5(A0)
Y轴—>P5.4(A1)
X轴—>P4.7(A6)
选择这3个引脚是因为板子上3个引脚正好在一起，方便连接。

配置ADC为3个通道连续循环转换，使用软件触发采样源，基准电压使用AVCC=3.3V。程序实现简单的倾斜和震动检测，当发生倾斜或者震动时点亮LED灯。可以调整感应灵敏度阈值。

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//
// main.c - MSP-EXP432P401R Out Of Box Demo
//
//Blinks RGB LED at 1Hz. Button S1 allows taps-to-beat that will
//match the RGB blink frequency to the tap frequency. Button S2
//cycles through 4 different color states, R/G/B/RandomColor, each
//with its saved blink frequency.
//
//The demo also accepts UART data from the Out Of Box GUI that
//allows changing the RGB LED's color with a color wheel and
//frequency by entering desired beats-per-minute
//
//****************************************************************************

#include <ti/devices/msp432p4xx/driverlib/driverlib.h>
#include <time.h>
#include <stdlib.h>

#define MCLK_FREQUENCY 3000000

int sysTickCount = 0;// Counts # of SysTick interrupts since last tap


/* UART Configuration Parameter. These are the configuration parameters to
 * make the eUSCI A UART module to operate with a 115200 baud rate. These
 * values were calculated using the online calculator that TI provides
 * at:
 *processors.wiki.ti.com/.../USCI_UART_Baud_Rate_Gen_Mode_Selection
 */
const eUSCI_UART_Config uartConfig =
{EUSCI_A_UART_CLOCKSOURCE_SMCLK,// SMCLK Clock Source26,// BRDIV = 260,// UCxBRF = 00,// UCxBRS = 0EUSCI_A_UART_NO_PARITY,// No ParityEUSCI_A_UART_LSB_FIRST,// MSB FirstEUSCI_A_UART_ONE_STOP_BIT,// One stop bitEUSCI_A_UART_MODE,// UART modeEUSCI_A_UART_LOW_FREQUENCY_BAUDRATE_GENERATION  // Low Frequency Mode
};

/* Statics */
static volatile uint16_t curADCResult;
static volatile float normalizedADCRes;
uint8_t		AdcValue[16];
uint32_t	tickcnt;


uint16_t	ADC_x[5];
uint16_t	ADC_y[5];
uint16_t	ADC_z[5];
uint16_t	ADC_x_cnt = 0;
uint16_t	ADC_y_cnt = 0;
uint16_t	ADC_z_cnt = 0;

uint16_t	ADC_x_cen = 0;	//ˮƽֵ
uint16_t	ADC_y_cen = 0;	//ˮƽֵ
uint16_t	ADC_z_cen = 0;	//ˮƽֵ

uint16_t	ADC_x_cur = 0;	//µ±Ç°Öµ
uint16_t	ADC_y_cur = 0;	//µ±Ç°Öµ
uint16_t	ADC_z_cur = 0;	//µ±Ç°Öµ

uint16_t SortValue(uint16_t *buf, uint16_t len)
{
	uint16_t	i,j;
	uint16_t	temp;
	
	if(len < 3)	return 0;	
	for(i=1; i<len; i++)
	{
		for(j = 0; j < (len-i); j++)
		{
			if(buf[j] > buf[j+1])
			{
				temp = buf[j];
				buf[j] = buf[j+1];
				buf[j+1] = temp;
			}
		}
	}
	temp = 0;
	for(i=1;i<(len-1);i++)
	{
		temp += buf[i];
	}
	temp /= (len-2);
	return temp;
	
}
/*
 * Main function
 */
int main(void)
{/* Halting WDT and disabling master interrupts */MAP_WDT_A_holdTimer();MAP_Interrupt_disableMaster();/* Initializing Variables */curADCResult = 0;
	AdcValue[0] = 0xff;
	AdcValue[1] = 0xff;
	AdcValue[2] = 0;
	AdcValue[3] = 0;
	AdcValue[4] = 0;
	AdcValue[5] = 0;
	AdcValue[6] = 0;
	AdcValue[7] = 0;
	AdcValue[8] = 0;
	AdcValue[9] = 0;/* Set the core voltage level to VCORE1 */MAP_PCM_setCoreVoltageLevel(PCM_VCORE1);/* Set 2 flash wait states for Flash bank 0 and 1*/MAP_FlashCtl_setWaitState(FLASH_BANK0, 2);MAP_FlashCtl_setWaitState(FLASH_BANK1, 2);/* Initialize main clock to 3MHz */MAP_CS_setDCOCenteredFrequency(CS_DCO_FREQUENCY_3);MAP_CS_initClockSignal(CS_MCLK, CS_DCOCLK_SELECT, CS_CLOCK_DIVIDER_1 );MAP_CS_initClockSignal(CS_HSMCLK, CS_DCOCLK_SELECT, CS_CLOCK_DIVIDER_1 );MAP_CS_initClockSignal(CS_SMCLK, CS_DCOCLK_SELECT, CS_CLOCK_DIVIDER_1 );/* Confinguring P1.1 & P1.4 as an input and enabling interrupts */MAP_GPIO_setAsInputPinWithPullUpResistor(GPIO_PORT_P1, GPIO_PIN1 | GPIO_PIN4);MAP_GPIO_clearInterruptFlag(GPIO_PORT_P1, GPIO_PIN1 | GPIO_PIN4);MAP_GPIO_enableInterrupt(GPIO_PORT_P1, GPIO_PIN1 | GPIO_PIN4);MAP_GPIO_interruptEdgeSelect(GPIO_PORT_P1, GPIO_PIN1 | GPIO_PIN4, GPIO_HIGH_TO_LOW_TRANSITION);/* Selecting P1.2 and P1.3 in UART mode */MAP_GPIO_setAsPeripheralModuleFunctionInputPin(GPIO_PORT_P1,GPIO_PIN2 | GPIO_PIN3, GPIO_PRIMARY_MODULE_FUNCTION);/* Configuring UART Module */MAP_UART_initModule(EUSCI_A0_BASE, &uartConfig);/* Enable UART module */MAP_UART_enableModule(EUSCI_A0_BASE);
	
	
	//P1.0,P2.0,P2.1,P2.2MAP_GPIO_setAsOutputPin(GPIO_PORT_P1, GPIO_PIN0);MAP_GPIO_setAsOutputPin(GPIO_PORT_P2, GPIO_PIN0 | GPIO_PIN1 | GPIO_PIN2);/* Enabling the FPU for floating point operation */MAP_FPU_enableModule();MAP_FPU_enableLazyStacking();//![Single Sample Mode Configure]/* Initializing ADC (MCLK/1/1) */MAP_ADC14_enableModule();MAP_ADC14_initModule(ADC_CLOCKSOURCE_MCLK, ADC_PREDIVIDER_1, ADC_DIVIDER_4,0);/* Configuring GPIOs (5.5 A0)(5.4 A1) */MAP_GPIO_setAsPeripheralModuleFunctionInputPin( GPIO_PORT_P5, GPIO_PIN4|GPIO_PIN5,
													GPIO_TERTIARY_MODULE_FUNCTION);
	//(4.7 A6)
	MAP_GPIO_setAsPeripheralModuleFunctionInputPin(GPIO_PORT_P4,GPIO_PIN7, 
													GPIO_TERTIARY_MODULE_FUNCTION);/* Configuring ADC Memory */MAP_ADC14_configureMultiSequenceMode(ADC_MEM0,ADC_MEM2, true);MAP_ADC14_configureConversionMemory(ADC_MEM0, ADC_VREFPOS_AVCC_VREFNEG_VSS,
										ADC_INPUT_A0, false);MAP_ADC14_configureConversionMemory(ADC_MEM1, ADC_VREFPOS_AVCC_VREFNEG_VSS,
										ADC_INPUT_A1, false);
	MAP_ADC14_configureConversionMemory(ADC_MEM2, ADC_VREFPOS_AVCC_VREFNEG_VSS,
										ADC_INPUT_A6, false);/* Configuring Sample Timer */MAP_ADC14_enableSampleTimer(ADC_MANUAL_ITERATION);/* Enabling/Toggling Conversion */MAP_ADC14_enableConversion();//![Single Sample Mode Configure]/* Configure and enable SysTick 1ms*/MAP_SysTick_setPeriod(1500);MAP_SysTick_enableModule();MAP_SysTick_enableInterrupt();
	/* Enabling interrupts */MAP_GPIO_clearInterruptFlag(GPIO_PORT_P1, GPIO_PIN1 | GPIO_PIN4);MAP_UART_enableInterrupt(EUSCI_A0_BASE, EUSCI_A_UART_RECEIVE_INTERRUPT);MAP_ADC14_enableInterrupt(ADC_INT0 | ADC_INT1 | ADC_INT2);MAP_Interrupt_enableInterrupt(INT_EUSCIA0);MAP_Interrupt_enableInterrupt(INT_PORT1);MAP_Interrupt_enableInterrupt(INT_ADC14);MAP_Interrupt_enableMaster();/* Main while loop */MAP_ADC14_toggleConversionTrigger();

	
	tickcnt = sysTickCount;while(1){
		if((sysTickCount -  tickcnt) > 10)
		{					
			MAP_UART_transmitData(EUSCI_A0_BASE, AdcValue[0]);
			MAP_UART_transmitData(EUSCI_A0_BASE, AdcValue[1]);
			MAP_UART_transmitData(EUSCI_A0_BASE, AdcValue[2]);
			MAP_UART_transmitData(EUSCI_A0_BASE, AdcValue[3]);
			MAP_UART_transmitData(EUSCI_A0_BASE, AdcValue[4]);
			MAP_UART_transmitData(EUSCI_A0_BASE, AdcValue[5]);
			MAP_UART_transmitData(EUSCI_A0_BASE, AdcValue[6]);
			MAP_UART_transmitData(EUSCI_A0_BASE, AdcValue[7]);
			MAP_UART_transmitData(EUSCI_A0_BASE, AdcValue[8]);
			MAP_UART_transmitData(EUSCI_A0_BASE, AdcValue[9]);
			
			if((ADC_x_cur > (ADC_x_cen + 0x800)) || 
				((ADC_x_cur + 0x800) < (ADC_x_cen)))
			{
				MAP_GPIO_setOutputHighOnPin(GPIO_PORT_P2, GPIO_PIN0);
			}else
			{
				MAP_GPIO_setOutputLowOnPin(GPIO_PORT_P2, GPIO_PIN0);
			}

			if((ADC_y_cur > (ADC_y_cen + 0x800)) || 
				((ADC_y_cur + 0x800) < (ADC_y_cen)))
			{
				MAP_GPIO_setOutputHighOnPin(GPIO_PORT_P2, GPIO_PIN1);
			}else
			{
				MAP_GPIO_setOutputLowOnPin(GPIO_PORT_P2, GPIO_PIN1);
			}

			if((ADC_z_cur > (ADC_z_cen + 0x800)) || 
				((ADC_z_cur + 0x800) < (ADC_z_cen)))
			{
				MAP_GPIO_setOutputHighOnPin(GPIO_PORT_P2, GPIO_PIN2);
			}else
			{
				MAP_GPIO_setOutputLowOnPin(GPIO_PORT_P2, GPIO_PIN2);
			}
			
			MAP_GPIO_setOutputLowOnPin(GPIO_PORT_P1, GPIO_PIN0);
			
			tickcnt = sysTickCount;
		}
		
//MAP_PCM_gotoLPM0();}
}

/*
 * Port 1 interrupt handler. This handler is called whenever switches attached
 * to P1.1 (S1) and P1.4 (S2) are pressed.
 */
void PORT1_IRQHandler(void)
{
//newTick = MAP_SysTick_getValue();uint32_t status = MAP_GPIO_getEnabledInterruptStatus(GPIO_PORT_P1);MAP_GPIO_clearInterruptFlag(GPIO_PORT_P1, status);/* Handles S1 button press */if (status & GPIO_PIN1){
		MAP_GPIO_setOutputHighOnPin(GPIO_PORT_P1, GPIO_PIN0);
		
		ADC_x_cen = ((AdcValue[6]<<8) | (AdcValue[7]));
		ADC_y_cen = ((AdcValue[4]<<8) | (AdcValue[5]));
		ADC_z_cen = ((AdcValue[2]<<8) | (AdcValue[3]));}/* Handles S2 button press */if (status & GPIO_PIN4){}
}//![Single Sample Result]
/* ADC Interrupt Handler. This handler is called whenever there is a conversion
 * that is finished for ADC_MEM0.
 */

void ADC14_IRQHandler(void)
{uint64_t 	status = MAP_ADC14_getEnabledInterruptStatus();MAP_ADC14_clearInterruptFlag(status);if (ADC_INT0 & status){curADCResult = MAP_ADC14_getResult(ADC_MEM0);normalizedADCRes = (curADCResult * 3.3) / 16384;
		
		ADC_z[ADC_z_cnt++] = curADCResult;
		if(ADC_z_cnt == 5)
		{
			ADC_z_cnt = 0;
			ADC_z_cur = SortValue(ADC_z, 5);
			AdcValue[2] = ADC_z_cur>>8; 
			AdcValue[3] = ADC_z_cur&0xff;			
		}MAP_ADC14_toggleConversionTrigger();}if (ADC_INT1 & status){curADCResult = MAP_ADC14_getResult(ADC_MEM1);normalizedADCRes = (curADCResult * 3.3) / 16384;
		
		ADC_y[ADC_y_cnt++] = curADCResult;
		if(ADC_y_cnt == 5)
		{
			ADC_y_cnt = 0;
			ADC_y_cur = SortValue(ADC_y, 5);
			AdcValue[4] = ADC_y_cur>>8; 
			AdcValue[5] = ADC_y_cur&0xff;			
		}MAP_ADC14_toggleConversionTrigger();}if (ADC_INT2 & status){curADCResult = MAP_ADC14_getResult(ADC_MEM2);normalizedADCRes = (curADCResult * 3.3) / 16384;
		
		ADC_x[ADC_x_cnt++] = curADCResult;
		if(ADC_x_cnt == 5)
		{
			ADC_x_cnt = 0;
			ADC_x_cur = SortValue(ADC_x, 5);
			AdcValue[6] = ADC_x_cur>>8; 
			AdcValue[7] = ADC_x_cur&0xff;			
		}MAP_ADC14_toggleConversionTrigger();}	
	
}
/*
 * SysTick interrupt handler. This handler toggles RGB LED on/off.
 */
void SysTick_Handler(void)
{
	sysTickCount++;
	
}

/*
 * EUSCI A0 UART interrupt handler. Receives data from GUI and sets LED color/blink frequency
 */
void EUSCIA0_IRQHandler(void)
{int receiveByte = UCA0RXBUF;/* Send acknowledgement to the GUI */MAP_UART_transmitData(EUSCI_A0_BASE, 'A');
	MAP_UART_transmitData(EUSCI_A0_BASE, receiveByte);


}

gaoyang9992006：

楼主的模块装备挺丰富的。

Susan Yang：

谢谢分享！

user5284236：

对MSP432的ADC做了很详细的介绍，通过对MMA7361的实际采样验证，贴出代码，讲解了硬件接线，很好的展示了ADC的功能。
程序也有结果展示，不错的评测。

user5845663：

很棒的介绍，还有示例程序，便于他人学习和验证。

user1913794：

楼主硬件有3路AD采样，同时果断的开源了代码，值得学习。同时对MSP432的ADC做了很详细的介绍，通过对MMA7361的实际采样验证，讲解了硬件接线，很好的展示了ADC的功能。

user5788289：

谢谢大家支持。

user5788289：

本来还计划准备加入OLED显示数据，和加速度传感器配合实现oled根据加速度值旋转屏幕，类是手机屏幕旋转功能的。由于时间关系，加上本身比较忙，就没完成该项功能。上面暂时就实现了倾斜XYZ方向点亮LED灯。后续有时间再深入测试一番，做点实际应用。

user3687004：

（1）项目开发不错，有过程有试验。
（2）ADC运用熟练，14位精度没有体现。
（3）两个方向的倾斜用不同颜色的灯指示，创意十足，就是测量精度堪忧。
（4）调整感应灵敏度阈值，没有体现。

user3735680：

这篇分享讲解的是ADC采样和加速度传感器的使用，通过对板卡的ADC文字描述和框图图片给出了ADC的一些参数，同时对加速度传感器简要介绍，接着给出了程序源码，并附上了实物图片，总的来说，具有比较好的参考价值！

ping yang：

1.楼主开源的做法值得肯定加赞赏。

2.评测不同方向加速度创意很好。

3.如果在倾斜角度上体现灵敏度阈值调节效果，相信大家会有更好的收获。感谢楼主的辛苦付出。