A/D Converter Operating Mode - NEC 78014Y Series User Manual

14.4.3 A/D converter operating mode

The operating mode is a select mode. One analog input channel is selected from among ANI0 to ANI7 with the
A/D converter input select register (ADIS) and A/D converter mode register (ADM) and start the A/D conversion.
The following two ways are available to start A/D conversion.
• Hardware start: Conversion is started by trigger input (INTP3).
• Software start: Conversion is started by setting ADM.
The A/D conversion result is stored in the A/D conversion result register (ADCR) and the interrupt request signal
(INTAD) is simultaneously generated.
(1) A/D conversion by hardware start
When bit 6 (TRG) and bit 7 (CS) of A/D converter mode register (ADM) are set to 1, the A/D conversion standby
state is set. When the external trigger signal (INTP3) is input, the A/D conversion starts on the voltage applied
to the analog input pins specified with bits 1 to 3 (ADM1 to ADM3) of ADM.
Upon termination of the A/D conversion, the conversion result is stored in the A/D conversion result register
(ADCR) and the interrupt request signal (INTAD) is generated. After one A/D conversion operation is started
and terminated, another operation is not started until a new external trigger signal is input.
If data with CS set to 1 is written to ADM again during A/D conversion, the converter suspends its A/D conversion
operation and waits for a new external trigger signal to be input. When the external trigger input signal is reinput,
A/D conversion is carried out from the beginning.
If data with CS set to 0 is written to ADM during A/D conversion, the A/D conversion operation stops immediately.
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A/D Conversion
Remark
Figure 14-6. A/D Conversion by Hardware Start
INTP3
ADM Rewrite
CS = 1, TRG = 1
Standby State
ADCR
INTAD
n = 0, 1, ..., 7
m = 0, 1, ..., 7
CHAPTER 14 A/D CONVERTER
Standby
ANIn ANIn ANIn
State
ANIn ANIn
ADM Rewrite
CS = 1, TRG = 1
Standby State ANIm
ANIn
ANIm ANIm
ANIm ANIm
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