M16C User Manual.pdf

A-D ConverterMitsubishi microcomputersM16C / 62 GroupSINGLE-CHIP 16-BIT CMOS MICROCOMPUTER2.7.6 Operation of A-D Converter (in repeat mode)In repeat mode, choose functions from those listed in Table 2.7.6. Operations of the circled items aredescribed below. Figure 2.7.13 shows timing chart, and Figure 2.7.14 shows the set-up procedure.Table 2.7.6. 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 operating.(2) After the first conversion is completed, the content of the successive comparison register(conversion result) is transmitted to A-D register i. The A-D conversion interrupt request bitdoes not go to “1”.(3) The A-D converter continues operating until the A-D conversion start flag is set to “0” bysoftware. The conversion result is transmitted to A-D register i every time a conversion iscompleted.(1) Start A-D conversion (2) Conversion result is transferred to the A-D register8-bit resolution : 28 φAD cycles10-bit resolution : 33 φAD cycles8-bit resolution : 28 φAD cycles10-bit resolution : 33 φAD cycles(3) A-D conversionis completeφADSet to “1” by softwareCleared to “0” by softwareA-D conversionstart flag“1”“0”A-D register iResultResultA-D conversionStop Convert Convert Convert StopNote: 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 cyclesfor 10-bit resolution.Figure 2.7.13. Operation timing of repeat mode396