MC9S08QE128 MCU Series Reference Manual, Rev. 2
Freescale Semiconductor
171
Analog Comparator (S08ACMPV3)
Figure 9-2. Analog Comparator (ACMP) Block Diagram
9.2
External Signal Description
The ACMP has two analog input pins, ACMPx+ and ACMPx- and one digital output pin ACMPxO. Each
of these pins can accept an input voltage that varies across the full operating voltage range of the MCU.
As shown in
, the ACMPx- pin is connected to the inverting input of the comparator, and the
ACMPx+ pin is connected to the comparator non-inverting input if ACBGS is a 0. As shown in
the ACMPxO pin can be enabled to drive an external pin.
The signal properties of ACMP are shown in
9.3
Register Definition
The ACMP includes one register:
•
An 8-bit status and control register
Table 9-1. Signal Properties
Signal
Function
I/O
ACMPx-
Inverting analog input to the ACMP. (Minus input)
I
ACMPx+
Non-inverting analog input to the ACMP. (Positive input)
I
ACMPxO
Digital output of the ACMP.
O
+
-
Interrupt
Control
Internal
Reference
ACBGS
Internal Bus
Status & Control
Register
A
CMOD
set A
CF
ACME
ACF
ACIE
ACOPE
Comparator
ACMPx
INTERRUPT
REQUEST
ACMPx+
ACMPx-
ACMPxO
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