CHAPTER 9 A/D CONVERTER
User’s Manual U11969EJ3V0UM00
319
9.8 Precautions Regarding Operations
9.8.1 Stop of conversion operations
When 0 is written to the CE bit of the ADM0 register during conversion, conversion stops and the conversion results
are not stored in the ADCRn register (n = 0 to 7).
9.8.2 Interval of the external/timer trigger
Set the interval (input time interval) of the trigger during the external or timer trigger mode longer than the conversion
time specified by the FR2 to FR0 bits of the ADM1 register.
When 0 < interval
≤
conversion operation time
When the next external trigger or timer trigger is input during conversion, conversion stops and conversion
starts according to the last timer trigger input.
When conversion operations are stopped, the conversion results are not stored in the ADCRn register
(n = 0 to 7). However, the number of triggers input are counted, and when an interrupt is generated, the
value at which conversion ended is stored in the ADCRn register.
9.8.3 Operation in the standby mode
(1) HALT mode
Continues A/D conversion operations. When canceled by NMI input, the ADM0/ADM1 register and ADCRn
register hold the value (n = 0 to 7).
(2) IDLE mode, STOP mode
As clock supply to the A/D converter is stopped, no conversion operations are performed. When canceled
using NMI input, the ADM0/ADM1 register and the ADCRn register hold the value (n = 0 to 7). However, when
these modes are set during conversion, conversion stops. At this time, if canceled using the NMI input, the
conversion operation resumes, but the conversion result written to the ADCRn register will become undefined.
In the IDLE and STOP modes, operation of the serial resistor string is also stopped to reduce the power
consumption. To further reduce current consumption, set the voltage of the AV
REF
to V
SS
.
9.8.4 Compare coincide interrupt in the timer trigger mode
The coincidence interrupt of the compare register becomes the A/D conversion start trigger and conversion
operations are started. At this time, the coincidence interrupt of the compare register also functions as the coincidence
interrupt of the compare register for the CPU. To prevent generation of the coincidence interrupt of the compare
register for the CPU, set interrupt disable using the interrupt mask bit (CC0MK3) of the interrupt control register
(CC0IC3).
Содержание V854 UPD703006
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