19 12-BIT A/D CONVERTER (ADC12A)
S1C31D50/D51 TECHNICAL MANUAL
Seiko Epson Corporation
19-7
(Rev. 2.00)
19.7 Control Registers
ADC12A Ch.
n
Control Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
ADC12A_nCTL
15 –
0
–
R
–
14–12 ADSTAT[2:0]
0x0
H0
R
11 –
0
–
R
10 BSYSTAT
0
H0
R
9–8 –
0x0
–
R
7–2 –
0x00
–
R
1
ADST
0
H0
R/W
0
MODEN
0
H0
R/W
Bit 15
Reserved
Bits 14–12 ADSTAT[2:0]
These bits indicate the analog input pin number
m
being A/D converted.
Table 19.7.1 Relationship Between Control Bit Value and Analog Input Pin
ADC12A_nCTL.ADSTAT[2:0] bits
ADC12A_nTRG.STAAIN[2:0] bits
ADC12A_nTRG.ENDAIN[2:0] bits
Analog input pin
0x7
ADINn7
0x6
ADINn6
0x5
ADINn5
0x4
ADINn4
0x3
ADINn3
0x2
ADINn2
0x1
ADINn1
0x0
ADINn0
These bits indicate the last converted analog input pin number after A/D conversion is forcefully
terminated by writing 0 to the ADC12A_
n
CTL.ADST bit or automatically terminated in one-time
conversion mode (ADC12A_
n
TRG.CNVMD = 0). If A/D conversion is stopped after the maximum
analog input pin number (different in each model) has been completed, these bits indicate ADIN
n
0.
Bit 11
Reserved
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 ADC12A_
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.