M16C User Manual.pdf

A-D ConverterMitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTER2.7.2 Operation of A-D converter (one-shot mode)In one-shot mode, choose functions from those listed in Table 2.7.2. Operations of the circled items aredescribed below. Figure 2.7.5 shows the operation timing, and Figure 2.7.6 shows the set-up procedure.Table 2.7.2. 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 begin operating.(2) After A-D conversion is completed, the content of the successive comparison register (conversionresult) is transmitted to A-D register i. At this time, the A-D conversion interrupt requestbit goes to “1”. Also, the A-D conversion start flag goes to “0”, and the A-D converterstops operating.(1) Start A-D conversion (2) A-D conversion 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 conversioninterrupt request“1”“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 2.7.5. Operation timing of one-shot mode388