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11.3 Structure of A/D Converter
Table 11.3-2 A/D Control Register 1 (ADC1) Bitss
Bit
Function
Bit 7
Bit 6
Bit 5
Unused bits
The read value is indeterminate.
Writing to these bits has no effect on the operation.
Bit 4
ADCK:
Input clock
selection bit
This bit selects the input clock used to activate the A/D
conversion or sense function when continuous activation is
specified (EXT = "1"). Setting this bit to "0" selects the
timebase timer output (divide=by=28 main clock source
oscillation). Setting this bit to "1" selects the 16-bit timer
output (TO1) in 8/16 timer/counter.
Check:
In the subclock mode, the main clock oscillator is stopped,
which means that the timebase timer output cannot be
used to trigger continuous mode conversions/comparisons.
Bit 3
ADIE:
Interrupt request
enable bit
This bit enables or disables an interrupt request output to
the CPU.
An interrupt request is output when both this bit and the
interrupt request flag bit (ADC1: ADI) are "1".
Bit 2
ADMD:
Function
selection bit
This bit switches between the A/D conversion function and
sense function.
The A/D converter operates as the A/D conversion function
when this bit is set to "0" and as the sense function when
this bit is set to "1".
Check:
Do not modify this bit when the conversion-in-progress bit
(ADC1: ADMV) is set to "1". Also, clear the interrupt
request flag bit (ADC1: ADI = "0") at switching functions.
Bit 1
EXT:
Continuous
activation enable
bit
This bit selects whether to activate the A/D conversion and
sense functions by software or to operate continuously
synchronized with an input clock.
Setting this bit to "0" enables software activation by the A/D
converter activation bit (ADC1: AD). Setting this bit to "1"
enables continuous activation on the rising edge of the
clock selected in the input clock selection bit (ADC2:
ADCK).
Bit 0
RESV1:
Reserved bit
Check:
Always write "1" to this bit.
The read value is always "1".