How to avoid the conflict values between adc multiple channels using polling method

[VRajk.1]

Hai,

I am working on the stm32f070c6 MCU , I just want to enable the multiple channels of ADC using polling method, all the channels are enabled for suppose when I connect the sensor to the AD0 pin the values coming from the sensor effects the all the channels(which I don't use(kept as floating) ), when I connect the all the channels to the 3.3V it is exact values at all the channels but when I use 1 or 2 channels the other channels are also effected and gives the values , actually I put a min value as 100 , if it greater than 100mv at particular channel it transmit the adc value, if it is less than 100mv it doesn't transmit the adc values to the serial monitor , problem is when i use less than 8 channels (either 1 or 2) the values are incorrect and effects to the all other channels , how can I overcome this problem if any one have idea please give a suggestion

Thanks and Regards

RAJ

[Ozone]

All channels of one ADC use the Sample&Hold capacitor.

This forms a simple first-order RC element, which needs to be charged / discharged to the input voltage of the channel.

If your sample times are too short, you get this bleed-over effect.

Calculate the RC behavior according to the STM datasheet and your input schematics, and adapt the required sample time accordingly.