M16C User Manual.pdf

A-D ConverterMitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTER2.7.4 Operation of A-D Converter (in one-shot mode, expanded analog input pin selected)In one-shot mode, choose functions from those listed in Table 2.7.4. Operations of the circled itemsare described below. Figure 2.7.9 shows timing chart, and Figure 2.7.10 shows the set-up procedure.Table 2.7.4. Choosed functionsItemSet-upItemSet-upOperation clockφADResolutionAnalog input pinOOODivided-by-4 fAD / dividedby-2fAD / fAD8-bit / 10-bitOne of AN0 pin to AN7 pinExpanded analoginput pinONot usedEither ANEX0 pin orANEX1 pinExternal operation amplifierconnection modeTrigger for startingA-D conversionOSoftware triggerTrigger by ADTRGSample & HoldONot activatedActivatedOperation (1) Setting the A-D conversion start flag to “1” causes the A-D converter to start the conversion onvoltage input to the ANEXi pin.(2) After the A-D conversion of voltage input to the ANEXi pin is completed, the content of thesuccessive comparison register (conversion result) is transmitted to the A-D register. At thesame time, the A-D conversion interrupt request bit goes to “1”. Also, the A-D conversion startflag goes to “0”, and the A-D converter stops operating.(1) Start A-D conversion (2) A-D convesion is complete8-bit resolution : 28 φAD cycles10-bit resolution : 33 φAD cyclesφADSet to “1” by softwareA-D conversionstart flag“1”“0”A-D register iResultA-D conversion“1”interrupt request “0”Cleared to “0” when interrupt request is accepted, or cleared by softwareNote: When φAD frequency is less than 1MHZ, sample and hold function cannot be selected.Conversion rate per analog input pin is 49 φAD cycles for 8-bit resolution and 59 φAD cycles for 10-bit resolution.Figure 2.7.9. Operation timing of one-shot mode, with expanded analog input pin selected392