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CY8C28xxx PSoC Programmable System-on-Chip TRM, Document No. 001-52594 Rev. *G
Switched Capacitor PSoC
®
Block
23.3.2
ASCxxCR1 Register
The Analog Switch Cap Type C Block Control Register 1
(ASCxxCR1) is one of four registers used to configure a type
C switch capacitor PSoC block.
Depending on the address of the registers in the above table
(in the “Add.” column), these registers are used for four and
two column PSoC devices (in the “Cols.” column).
Bits 7 to 5: ACMUX[2:0].
These bits control the input mux-
ing for both the A and C capacitor branches. The high order
bit, ACMux[2], selects one of two inputs for the C branch.
Bits 4 to 0: BCap[4:0].
The BCap bits set the value of the
capacitor in the B path.
For additional information, refer to the
23.3.3
ASCxxCR2 Register
The Analog Switch Cap Type C Block Control Register 2
(ASCxxCR2) is one of four registers used to configure a type
C switch capacitor PSoC block.
Depending on the address of the registers in the above table
(in the “Add.” column), these registers are used for four and
two column PSoC devices (in the “Cols.” column).
Bit 7: AnalogBus.
This bit gates the output to the analog
column bus (ABUS). The output on the ABUS is affected by
the state of the ClockPhase bit in the Control 0 register. If
AnalogBus is set to ‘0’, the output to the analog column bus
is tri-stated. If AnalogBus is set to ‘1’, the signal that is out-
put to the analog column bus is selected by the ClockPhase
bit. If the ClockPhase bit is ‘0’, the block output is gated by
sampling clock on the last part of PHI2. If the ClockPhase bit
is ‘1’, the block output continuously drives the ABUS.
Bit 6: CompBus.
This bit controls the output to the column
comparator bus (CBUS). Note that if the CBUS is not driven
by anything in the column, it is pulled low. The comparator
output is evaluated on the rising edge of internal PHI1 and is
latched so it is available during internal PHI2.
Bit 5: AutoZero.
This bit controls the shorting of the output
to the inverting input of the opamp. When shorted, the
opamp is basically a follower. The output is the opamp off-
set. By using the feedback capacitor of the integrator, the
block can memorize the offset and create an offset cancella-
tion scheme. AutoZero also controls a pair of switches
between the A and B branches and the summing node of
the opamp. If AutoZero is enabled, then the pair of switches
is active. AutoZero also affects the function of the FSW1 bit
in the Control 3 register.
Bits 4 to 0: CCap[4:0].
The CCap bits set the value of the
capacitor in the C path.
For additional information, refer to the
Add.
Name
Cols.
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Access
0,81h
4, 2
ACMux[2:0]
BCap[4:0]
RW : 00
0,89h
4
ACMux[2:0]
BCap[4:0]
RW : 00
0,95h
4, 2
ACMux[2:0]
BCap[4:0]
RW : 00
0,9Dh
4
ACMux[2:0]
BCap[4:0]
RW : 00
Add.
Name
Cols.
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Access
0,82h
4, 2
AnalogBus
CompBus
AutoZero
CCap[4:0]
RW : 00
0,8Ah
4
AnalogBus
CompBus
AutoZero
CCap[4:0]
RW : 00
0,96h
4, 2
AnalogBus
CompBus
AutoZero
CCap[4:0]
RW : 00
0,9Eh
4
AnalogBus
CompBus
AutoZero
CCap[4:0]
RW : 00
Summary of Contents for CY8C28 series
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