MC9S08DN60F1CLF datasheet(166/356 Pages) FREESCALE

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Chapter 9 Analog Comparator (S08ACMPV3)

MC9S08DN60 Series Data Sheet, Rev 3

166

Freescale Semiconductor

9.4

Functional Description

The analog comparator can compare two analog input voltages applied to ACMPx+ and ACMPx

−, or it

can compare an analog input voltage applied to ACMPx

− with an internal bandgap reference voltage.

ACBGS selects 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 selects the condition that causes ACF to be set. ACF can be set on a rising edge of the comparator

output, a falling edge of the comparator output, or 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.

ACO

Analog Comparator Output. Reading ACO returns the current value of the analog comparator output. ACO is

reset to a 0 and reads as a 0 when the ACMP is disabled (ACME = 0).

ACOPE

Analog Comparator Output Pin Enable. Enables 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

1:0

ACMOD

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

Table 9-3. ACMPxSC Field Descriptions (continued)

Field

Description

MC9S08DN60F1CLF Datasheet(PDF) 166 Page - Freescale Semiconductor, Inc