R01UH0822EJ0100 Rev.1.00
Page 832 of 1041
Jul 31, 2019
RX13T Group
26. 12-Bit A/D Converter (S12ADF)
26.2.14
A/D Sample-and-Hold Circuit Control Register (ADSHCR)
ADSHCR sets the parameters related to channel-dedicated sample-and-hold circuits.
SSTSH[7:0] Bits (Channel-Dedicated Sample-and-Hold Circuit Sampling Time Setting)
These bits set the sampling time for the channel-dedicated sample-and-hold circuits. If one state is one ADCLK (A/D
conversion clock) cycle and the ADCLK clock is 32 MHz, one state is 31.25 ns. The initial value is 26 states. If the
impedance of analog input signal source is too high to secure sufficient sampling time or if the ADCLK clock is slow, the
sampling time can be adjusted. The SSTSH[7:0] bits should be set while the ADCSR.ADST bit is 0. The sampling time
must be set to a value that is 4 states or more and is 255 or less. Also, the sampling state setting value should be at least
the specified test condition in
section 32.5, A/D Conversion Characteristics
.
SHANS[2:0] Bits (Channel-Dedicated Sample-and-Hold Circuit Bypass Select)
These bits select whether to use or not use (bypass) AN000 to AN002 channel-dedicated sample-and-hold circuits. The
SHANS[0] bit selects AN000, SHANS[1] bit selects AN001, and SHANS[2] bit selects AN002. The SHANS[2:0] bits
should be set while the ADCSR.ADST bit is 0.
If any channel from among AN000 to AN002 is selected for group B or C while operation is in group scan mode under
group priority control, make the setting to bypass the channel-dedicated sample-and-hold circuit.
Address(es): S12AD.ADSHCR 0008 9066h
b15
b14
b13
b12
b11
b10
b9
b8
b7
b6
b5
b4
b3
b2
b1
b0
—
—
—
—
—
SHANS[2:0]
SSTSH[7:0]
Value after reset:
0
0
0
0
0
0
0
0
0
0
0
1
1
0
1
0
Bit
Symbol
Bit Name
Description
R/W
b7 to b0
Channel-Dedicated Sample-and-Hold
Circuit Sampling Time Setting
Set the sampling time (4 to 255 states).
R/W
b10 to b8
Channel-Dedicated Sample-and-Hold
Circuit Bypass Select
Select whether to use or not use (bypass) AN000 to
AN002 channel-dedicated sample-and-hold circuits.
0: Bypass the channel-dedicated sample-and-hold
circuits.
1: Use the channel-dedicated sample-and-hold circuits.
R/W
b15 to b11 —
Reserved
These bits are read as 0. The write value should be 0.
R/W