MC9S08DN60 Datasheet, PDF (164/354 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 9 Analog Comparator (S08ACMPV3)
Table 9-3. ACMPxSC Field Descriptions (continued)
Field
3
ACO
2
ACOPE
1:0
ACMOD
Description
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).
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
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
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.
MC9S08DN60 Series Data Sheet, Rev 2
164
Freescale Semiconductor