Using STM8L051 ADC PD0, 3.7V~4.2V Li-Po battery, 1M+1M resistor to divde the battery voltage, 100nF capacitor to GND.
If set PD0 floating input and halt, total current 40uA, if set PD0 push-pull output LOW, 10uA. But the drawback of output LOW is that I have to wait 350ms for the 100nF cap charging before a new ADC reading.
Is there any method to reduce current consumption and remain floating input?
GPIOD->CR2 &= ~0x01; // External interrupt disable
GPIOD->CR1 &= ~0x01; // Floating input
GPIOD->DDR &= ~0x01; // Input
delay_ms(350); //Waiting capacitor charging and stable
/* Enable ADC1 peripheral clock*/
CLK->PCKENR2 |= 1<<0;
/*clear CR1 register */
ADC1->CR1 = 0x00;
/* set the resolution and the conversion mode */
ADC1->CR1 |= 1<<2; //continuous mode, 12bit
//ADC1->CR1 &= ~(1<<2); //single mode, 12bit
/*clear CR2 register */
ADC1->CR2 &= ~0x80;
/* set the Prescaler */
ADC1->CR2 |= 0x80; //CLK/2
/* Configures the sampling time for the Slow ADC channel group. */
ADC1->CR2 &= ~0x07;
ADC1->CR2 |= 0x07; //384 cycles
/* Set the ADON bit to wake up the specified ADC from power down mode */
ADC1->CR1 |= 0x01;
/* Enable the selected ADC channel(s). */
ADC1->SQR[1] |= 1<<6; //SQR2, PD0 channel 22
/* Clear EOC flag */
//ADC1->SR &= ~0x01;
/* Start the ADC software conversion */
ADC1->CR1 |= 0x02;
for(i=0;i<8;i++)
{
//ADC1->CR1 |= 0x02;
while((ADC1->SR & 0x01) == 0x00);
temp = (uint16_t)(ADC1->DRH);
temp = (uint16_t)((uint16_t)((uint16_t)temp << 8) | ADC1->DRL);
ADCdata += temp;
}
ADCdata >>= 3;
/* power down mode */
ADC1->CR1 &= ~0x01;
/* Disable the selected ADC channel(s). */
ADC1->SQR[1] &= ~(1<<6); //SQR2, PD0 channel 22
/* Disable ADC1 peripheral clock*/
CLK->PCKENR2 &= ~0x01;
// PD0, ADC_IN
GPIOD->CR2 &= ~0x01; // 2MHz slow
GPIOD->CR1 |= 0x01; // Push-pull
GPIOD->ODR &= ~0x01; // Output Low
GPIOD->DDR |= 0x01; // Output
