261CHAPTER 14 A/D CONVERTER14.1 A/D Converter FunctionsThe A/D converter converts an analog input into a digital value. It consists of 8 channels (ANI0 to ANI7) with an8-bit resolution.The conversion method is based on successive approximation and the conversion result is held in the 8-bit A/Dconversion result register (ADCR).The following two methods are used for starting an A/D conversion operation.(1) Hardware startConversion is started by trigger input (INTP3).(2) Software startConversion is started by setting the A/D converter mode register (ADM).Select 1 channel from the analog inputs ANI0 to ANI7 and execute A/D conversion. An A/D conversion operationends after the A/D conversion operation at hardware start is completed and an interrupt request (INTAD) is generated.In the case of software start, the A/D conversion operation is repeated. Each time an A/D conversion ends, an interruptrequest (INTAD) is generated.Cautions For pins which have common functions with a port (See 3.1.1 or 4.1.1 Normal operating modepins, (1) Port pins), do not execute the following operations during A/D conversion. Ifperformed, then the general error standards cannot be maintained during A/D conversion.<1> If it is used as a port, rewriting the output latch of its output.<2> Even if it is not used as a port, changing the output level of pins used as outputs.
