Programming Manual Elektor Proton Robot - ELEKTOR.se

Analogue to digital conversion explainedMost modern microcontrollers have 1 analogue to digital convertor onboard. This one ADconvertor input is multiplexed to several input pins of the uC – giving these pins A/Dfunctionality.MICROCONTROLLER WITHEMBEDDED AD CONVERTORAN0AN1ANALOGMULTIPLEXERAN2RESULTA/DCONVERTORAN3AN4AN58 BIT RESULT10 BIT RESULTAN6AN7The result of the AD convertor – in many cases – is a 10 bit binary (digital) value. In most cases –an accuracy of 8 bit is sufficient – so we can choose to only use the 8 MSB’s – or the full 10 bits.The Analogue values are measured between 0 and 5V – 0v resulting in an 8 bit digital value of0b00000000 (or 0) and 5V resulting in an 8 bit digital value of 0b11111111 (or 255). For example:2.5V will result in 0b10000000 (or 128).In robotics – often analogue sensors (like the sharp sensors) are used to measure distance –temperature – humidity – light intensity – sound pressure - …With the embedded A/D convertors of modern microcontrollers – it is no problem at all toconnect these sensors directly to the analogue input pins of the microcontroller.Bart Huyskens Manual Elektor Proton V1.0 3 April 2011 85