CHAPTER 11 A/D CONVERTER
User’s Manual U13850EJ4V0UM
354
11.4.3 A/D converter operation mode
In this mode one of the analog input channels ANI0 to ANI11 is selected by the analog input channel specification
register (ADS) and A/D conversion is executed.
The A/D conversion can be started in the following two ways:
•
Hardware start:
Started by trigger input (ADTRG) (rising edge, falling edge, or both rising and falling edges
can be specified)
•
Software start:
Started by setting A/D converter mode register 1 (ADM1)
The result of the A/D conversion is stored in the A/D conversion result register (ADCR) and an interrupt request
signal (INTAD) is generated at the same time.
(1) A/D conversion by hardware start
A/D conversion is on standby if bit 6 (TRG) and bit 7 (ADCS) of A/D converter mode register 1 (ADM1) are set to
1. When an external trigger signal is input, the A/D converter starts converting the voltage applied to the analog
input pin specified by the analog input channel specification register (ADS) into a digital signal.
When the A/D conversion has been completed, the result of the conversion is stored in the A/D conversion result
register (ADCR), and an interrupt request signal (INTAD) is generated. Once the A/D conversion has been
started and completed, conversion is not started again unless a new external trigger signal is input.
If data with ADCS set to 1 is written to ADM during A/D conversion, the conversion under execution is stopped,
and the A/D converter stands by until a new external trigger signal is input. If the external trigger signal is input,
A/D conversion is executed again from the beginning.
If data with ADCS set to 0 is written to ADM1 during A/D conversion, the conversion is immediately stopped.
Figure 11-7. A/D Conversion by Hardware Start (with Falling Edge Specified)
Rewriting ADS
ADCS = 1, TRG = 1
Rewriting ADS
ADCS = 1, TRG = 1
A/D conversion
ADCR
INTAD
ANIn
Standby
status
Standby
status
Standby
status
ANIn
ANIn
ANIm
ANIm
ANIm
ANIn
ANIn
ANIn
ANIm
ANIm
External trigger
input signal
Remarks 1.
n = 0, 1, ..., 11
2.
m = 0, 1, ..., 11
Содержание MPD703030A
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