Operation Mode Of 10-Bit A/D Converter - NEC mPD789426 Series User Manual

CHAPTER 11 10-BIT A/D CONVERTER ( µ µ µ µ PD789436 AND 789456 SUBSERIES)

11.4.3 Operation mode of 10-bit A/D converter

The A/D converter is initially in select mode. In this mode, analog input channel specification register 0 (ADS0) is
used to select an analog input channel from ANI0 to ANI5 for A/D conversion.
A/D conversion can be started only by software, that is, by setting A/D converter mode register 0 (ADM0).
The A/D conversion result is saved to A/D conversion result register 0 (ADCR0). At the same time, an interrupt
request signal (INTAD0) is generated.
• • • • Software-started A/D conversion
Setting bit 7 (ADCS0) of A/D converter mode register 0 (ADM0) to 1 triggers A/D conversion for a voltage
applied to the analog input pin specified in A/D input selection register 0 (ADS0).
Upon completion of A/D conversion, the conversion result is saved to A/D conversion result register 0
(ADCR0). At the same time, an interrupt request signal (INTAD0) is generated. Once A/D conversion is
activated, and completed, another session of A/D conversion is started. A/D conversion is repeated until new
data is written to ADM0.
If data where ADCS0 is 1 is written to ADM0 again during A/D conversion, the ongoing session of A/D
conversion is discontinued, and a new session of A/D conversion begins for the new data.
If data where ADCS0 is 0 is written to ADM0 again during A/D conversion, A/D conversion is stopped
immediately.
Rewriting ADM0
ADCS0 = 1
A/D conversion
ADCR0
INTAD0
Remarks 1. n = 0 to 5
2. m = 0 to 5
Figure 11-6. Software-Started A/D Conversion
ANIn ANIn
ANIn
User's Manual U15075EJ1V0UM00
Overwriting ADM0
ADCS0 = 1
ANIn ANIm
Conversion is
discontinued;
no conversion
result is preserved.
ANIn
ADCS0 = 0
ANIm
Stop
ANIm
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