通过带隙电压测量VCC

1万 · 2019-4-25 23:58

如果我们可以确定带隙电压和对应的ADC原始数据那么我们就可以通过比例运算知道VCC，因为满量程对应的就是VCC，也就是0x0FFF对应VCC
即VCC:0xFFF=带隙电压：带隙电压ADC

1万 · 2019-4-25 23:58

double Bandgap_Voltage,VDD_Voltage;

void ADC_Bypass (void) // The first three times convert should be

bypass

{

unsigned char ozc;

for (ozc=0;ozc<0x03;ozc++)

{

clr_ADCF;

set_ADCS;

while(ADCF == 0);

}

}

void main (void)

{

double bgvalue;

READ_BANDGAP();

Enable_ADC_BandGap;

ADC_Bypass();

clr_ADCF;

set_ADCS;

while(ADCF == 0);

bgvalue = (ADCRH<<4) + ADCRL;

VDD_Voltage = (0xFFF/bgvalue)*Bandgap_Voltage;

printf ("\n Bandgap voltage = %e", Bandgap_Voltage);

printf ("\n VDD voltage = %e", VDD_Voltage);

 while(1);

}

1万 · 2019-4-25 23:59

而带隙电压可以通过特定的操作获取

复制

#define set_IAPEN

BIT_TMP=EA;EA=0;TA=0xAA;TA=0x55;CHPCON|=SET_BIT0 ;EA=BIT_TMP

#define set_IAPGO

BIT_TMP=EA;EA=0;TA=0xAA;TA=0x55;IAPTRG|=SET_BIT0 ;EA=BIT_TMP

#define clr_IAPEN

BIT_TMP=EA;EA=0;TA=0xAA;TA=0x55;CHPCON&=~SET_BIT0;EA=BIT_TMP

void READ_BANDGAP()

{

UINT8 BandgapHigh,BandgapLow;

Set_IAPEN; // Enable IAPEN

IAPAL = 0x0C;

IAPAH = 0x00;

IAPCN = 0x04;

set_IAPGO; // Trig set IAPGO

BandgapHigh = IAPFD;

IAPAL = 0x0d;

IAPAH = 0x00;

IAPCN = 0x04;

set_IAPGO; // Trig set IAPGO

BandgapLow = IAPFD;

BandgapLow = BandgapLow&0x0F;

Clr_IAPEN; // Disable IAPEN

Bandgap_Value = (BandgapHigh<<4)+BandgapLow;

Bandgap_Voltage = 3072/(0x1000/Bandgap_Value);