12.2 Register Descriptions
12.2.1 A/D Result Registers (ADRRH, ADRRL)
ADRRH and ADRRL together comprise a 16-bit read-only register for holding the results of
analog-to-digital conversion. The upper 8 bits of the data are held in ADRRH, and the lower 2 bits
in ADRRL.
ADRRH and ADRRL can be read by the CPU at any time, but the ADRRH and ADRRL values
during A/D conversion are not fixed. After A/D conversion is complete, the conversion result is
stored as 10-bit data, and this data is held until the next conversion operation starts.
ADRRH and ADRRL are not cleared on reset.
12.2.2 A/D Mode Register (AMR)
AMR is an 8-bit read/write register for specifying the A/D conversion speed, external trigger option,
and the analog input pins.
Upon reset, AMR is initialized to H'30.
Bit 7: Clock select (CKS)
Bit 7 sets the A/D conversion speed.
Bit 7
Conversion Time
CKS
Conversion Period
ø = 1 MHz
ø = 5 MHz
0
62/ø (initial value)
62 µs
31 µs
1
31/ø
31 µs
15.5 µs
*
Note:
*
Operation is not guaranteed if the conversion time is less than 15.5 µs. Set bit 7 for a value
of at least 15.5 µs.
Bit
Initial value
Read/Write
7
CKS
0
R/W
6
TRGE
0
R/W
5
—
1
—
4
—
1
—
3
CH3
0
R/W
0
CH0
0
R/W
2
CH2
0
R/W
1
CH1
0
R/W
Bit
7
6
5
4
3
ADRRH
ADRRL
0
2
1
7
6
5
4
3
0
2
1
Initial value
Read/Write
Not
fixed
R
Not
fixed
R
Not
fixed
R
Not
fixed
R
Not
fixed
R
Not
fixed
R
Not
fixed
R
Not
fixed
R
Not
fixed
R
Not
fixed
R
—
—
—
—
—
—
—
—
—
—
—
—
ADR9 ADR8 ADR7 ADR6 ADR5
ADR2
ADR4 ADR3
ADR1 ADR0
—
—
—
—
—
—
315