We always say that the pcDuino is compatible with arduino platform, but there are some different in some part, here I will introduce the different of ADC between the pcDuino and arduino and what we should pay attention to in a normal application.
1.Accuracy difference: arduino platforms are generally atmel’s AVR SCM, ADC accuracy of these SCM is 10 bite, while the ADC accuracy of pcduino has two kinds, one is six bite, one is 12 bite, many people will certainly ask and why there is a six precision ADC and what’s this for. The answer is: A10 is a chip for flat-panel manufacturers, this six precision ADC wise full name is LRADC (Low Resolution Analog To Digital Converter) which is used to make key identify . On pcDuino there are two circuit which has six bite ADC, the compatible interface on arduino are respectively A0 and A1, the another four circuits (A2-A5) is a resistive touch screen controllers. Due to the difference of the precision, we should pay attention to the problem when transplant the arduino code to pcduino.
2. Conversion rate: Generally the largest conversion rate of AVR microcontroller ADC is 15KSPS, so that we can reduce the accuracy to improve the sampling rate and here the pcDuino has two types, one is LRADC, this maximum conversion rate is 250HZ, while the maximum conversion speed of another 12 bite progress is 125KSPS.
3.Range: general arduino ADC reference voltage is 5V, so its range is also 5V, while pcduino ADC reference voltage is 3.3V, so pcduino ADC range is only 3.3V, if you want to measure 5V signal outside, we should use a resistor divider.