19 12-BIT A/D CONVERTER (ADC12A)
S1C17M20/M21/M22/M23/M24/M25
Seiko Epson Corporation
19-7
TECHNICAL MANUAL (Rev. 1.0)
Bit 10
BSYSTAT
This bit indicates whether the ADC12A is executing A/D conversion or not.
1 (R/W): A/D converting
0 (R/W): Idle
Bits 9–2
Reserved
Bit 1
ADST
This bit starts A/D conversion or enables to accept triggers.
1 (R/W): Start sampling and conversion (software trigger)/
Enable trigger acceptance (external trigger, 16-bit timer underflow trigger)
0 (R/W): Terminate conversion
This bit does not revert to 0 automatically after A/D conversion has completed. Write 0 to this bit once
and write 1 again to start another A/D conversion. After 0 is written to this bit to forcefully terminate
conversion, the ADC12A stops after the A/D conversion being executed is completed. Therefore, this
bit cannot be used to determine whether the ADC12A is executing A/D conversion or not.
Note
: The data written to the ADC12_
n
CTL.ADST bit must be retained for one or more CLK_T16_
k
clock cycles when 1 is written or two or more CLK_T16_
k
clock cycles when 0 is written.
Bit 0
MODEN
This bit enables the ADC12A operations.
1 (R/W): Enable ADC12A operations (The operating clock is supplied.)
0 (R/W): Disable ADC12A operations (The operating clock is stopped.)
Note
: After 0 is written to the ADC12_
n
CTL.MODEN bit, the ADC12A executes a terminate
processing. Before the clock source is deactivated, read the ADC12_
n
CTL.MODEN bit to
make sure that it is set to 0.
ADC12A Ch.
n
Trigger/Analog Input Select Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
ADC12_nTRG
15–14 –
0x0
–
R
–
13–11 ENDAIN[2:0]
0x0
H0
R/W
10–8 STAAIN[2:0]
0x0
H0
R/W
7
STMD
0
H0
R/W
6
CNVMD
0
H0
R/W
5–4 CNVTRG[1:0]
0x0
H0
R/W
3
–
0
–
R
2–0 SMPCLK[2:0]
0x7
H0
R/W
Note: Make sure that the ADC12_nCTL.BSYSTAT bit is set to 0 before altering the ADC12_nTRG register.
Bits 15–14 Reserved
Bits 13–11 ENDAIN[2:0]
These bits set the analog input pin to be A/D converted last.
See Table 19.6.1 for the relationship between analog input pins and bit setting values.
Note
: The analog input pin range to perform A/D conversion must be set as ADC12_
n
TRG.
ENDAIN[2:0] bits
≥
ADC12_
n
TRG.STAAIN[2:0] bits.
Bits 10–8 STAAIN[2:0]
These bits set the analog input pin to be A/D converted first.
See Table 19.6.1 for the relationship between analog input pins and bit setting values.