MC9S12G FREESCALE [Freescale Semiconductor, Inc], MC9S12G Datasheet - Page 418

• Manufacturer Part Number: MC9S12G
• Description: Ignores external trigger. Performs one conversion sequence and stops.
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Analog-to-Digital Converter (ADC10B12CV2)
12.4.2
This subsection describes some of the digital features in more detail. See
Descriptions”
12.4.2.1
The external trigger feature allows the user to synchronize ATD conversions to an external event rather
than relying only on software to trigger the ATD module when a conversions is about to take place. The
external trigger signal (out of reset ATD channel 11, configurable in ATDCTL1) is programmable to be
edge or level sensitive with polarity control.
combinations of control bits and their effect on the external trigger function.
In either level or edge sensitive modes, the first conversion begins when the trigger is received.
Once ETRIGE is enabled a conversion must be triggered externally after writing to ATDCTL5 register.
During a conversion in edge sensitive mode, if additional trigger events are detected the overrun error flag
ETORF is set.
If level sensitive mode is active and the external trigger de-asserts and later asserts again during a
conversion sequence, this does not constitute an overrun. Therefore, the flag is not set. If the trigger is left
active in level sensitive mode when a sequence is about to complete, another sequence will be triggered
immediately.
418
This document is valid for the S12G96 and the S12G128 device. All information related to other devices is preliminary.
Digital Sub-Block
External Trigger Input
ETRIGLE
for all details.
X
X
0
0
1
1
ETRIGP
X
X
0
1
0
1
Table 12-23. External Trigger Control Bits
MC9S12G Family Reference Manual,
ETRIGE
0
0
1
1
1
1
Table 12-23
SCAN
0
1
X
X
X
X
gives a brief description of the different
Ignores external trigger. Performs one
conversion sequence and stops.
Ignores external trigger. Performs
continuous conversion sequences.
Trigger falling edge sensitive. Performs
one conversion sequence per trigger.
Trigger rising edge sensitive. Performs one
conversion sequence per trigger.
Trigger low level sensitive. Performs
continuous conversions while trigger level
is active.
Trigger high level sensitive. Performs
continuous conversions while trigger level
is active.
Rev.1.01
Description
Section 12.3.2, “Register
Freescale Semiconductor