How to sample improve ADC speed?

[STM32L09]

My application senario: sample the sensor signal every second, and transmit through UART. 

to save power supply, I select ADC single mode, and used average as filter.

void ConfigureADC(void)
{
ADC1->CFGR1 |= ADC_CFGR1_AUTOFF;
ADC1->CFGR2 = (ADC1->CFGR2 & (~ADC_CFGR2_CKMODE))
| (ADC_CFGR2_OVSE | ADC_CFGR2_OVSR_2 | ADC_CFGR2_OVSR_1 | ADC_CFGR2_OVSR_0| ADC_CFGR2_OVSS_2); 
ADC1->SMPR |= ADC_SMPR_SMP_0 | ADC_SMPR_SMP_1 | ADC_SMPR_SMP_2; 
ADC1->CR |= ADC_CR_ADEN; 
ADC->CCR |= ADC_CCR_VREFEN|ADC_CCR_TSEN; 
}


unsigned int SignleADC(unsigned long int channel)
{
ADC1->CHSELR = channel; 
ADC1->CR |= ADC_CR_ADSTART;
while ((ADC1->ISR & ADC_ISR_EOC) == 0) 
{
}
ADC1->CR |= ADC_CR_ADSTP;
return ADC1->DR;
}

unsigned int Sensor_Read(void)
{
unsigned int gas[128];
unsigned long int read=0;
for(unsigned char i=0;i<128;i++)
gas[i] = SignleADC(ADC_CHSELR_CHSEL5);
for(unsigned char i=0;i<128;i++)
read += gas[i];

read = read>>7;
return((unsigned int)read);
}

Now the run time for Sensor_Read is about 700ms, it's too long, how can I improve the speed?

 

[Tesla DeLorean]

The most obvious would be to sum/average over fewer samples, or use the longer sample/hold to negate the need.

[STM32L09]

thanks, but 128 is minimum, otherwise the noise too high

[TDK]

Convert with DMA in background. Perform averaging on demand when you send out sample.

[mƎALLEm]

Hello @STM32L09 ,

In next time please use </> button to paste your code. See this post. I've edited your post.

 

[STM32L09]

got it.

[STM32L09]

currently my idea is：

1. Configure ADC and DMA to sample PA0 and PA5 16 times

2. Re-configure ADC and DMA to sample PA5 256-16 times

repeat step 1.