mcf51ac256a Freescale Semiconductor, Inc, mcf51ac256a Datasheet - Page 166

• Manufacturer Part Number: mcf51ac256a
• Description: Mcf51ac Flexis
• Manufacturer: Freescale Semiconductor, Inc

Analog Comparator (ACMPV3)
8.4
The analog comparator can be used to compare two analog input voltages applied to ACMPx+ and
ACMPx-; or it can be used to compare an analog input voltage applied to ACMPx- with an internal
bandgap reference voltage. ACBGS is used to select between the bandgap reference voltage or the
ACMPx+ pin as the input to the non-inverting input of the analog comparator. The comparator output is
high when the non-inverting input is greater than the inverting input, and is low when the non-inverting
input is less than the inverting input. ACMOD is used to select the condition which will cause ACF to be
set. ACF can be set on a rising edge of the comparator output, a falling edge of the comparator output, or
either a rising or a falling edge (toggle). The comparator output can be read directly through ACO. The
comparator output can be driven onto the ACMPxO pin using ACOPE.
8-6
ACMOD
ACBGS
ACOPE
ACME
Field
ACIE
ACO
ACF
1:0
7
6
5
4
3
2
Functional Description
Analog Comparator Module Enable — ACME enables the ACMP module.
0 ACMP not enabled
1 ACMP is enabled
Analog Comparator Bandgap Select — ACBGS is used to select between the bandgap reference voltage or
the ACMPx+ pin as the input to the non-inverting input of the analog comparatorr.
0 External pin ACMPx+ selected as non-inverting input to comparator
1 Internal reference select as non-inverting input to comparator
Note: refer to this chapter introduction to verify if any other config bits are necessary to enable the bandgap
Analog Comparator Flag — ACF is set when a compare event occurs. Compare events are defined by ACMOD.
ACF is cleared by writing a one to ACF.
0 Compare event has not occured
1 Compare event has occured
Analog Comparator Interrupt Enable — ACIE enables the interrupt from the ACMP. When ACIE is set, an
interupt will be asserted when ACF is set.
0 Interrupt disabled
1 Interrupt enabled
Analog Comparator Output — Reading ACO will return the current value of the analog comparator output. ACO
is reset to a 0 and will read as a 0 when the ACMP is disabled (ACME = 0).
Analog Comparator Output Pin Enable — ACOPE is used to enable the comparator output to be placed onto
the external pin, ACMPxO.
0 Analog comparator output not available on ACMPxO
1 Analog comparator output is driven out on ACMPxO
Analog Comparator Mode — ACMOD selects the type of compare event which sets ACF.
00 Encoding 0 — Comparator output falling edge
01 Encoding 1 — Comparator output rising edge
10 Encoding 2 — Comparator output falling edge
11 Encoding 3 — Comparator output rising or falling edge
reference in the chip level.
MCF51AC256 ColdFire Integrated Microcontroller Reference Manual, Rev. 5
Table 8-3. ACMPx Status and Control Register Field Descriptions
Description
Freescale Semiconductor