mc68hc916y3 Freescale Semiconductor, Inc, mc68hc916y3 Datasheet - Page 295

• Manufacturer Part Number: mc68hc916y3
• Description: Mc68hc16y3 16 Bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

13.5 Pin Descriptions
13.5.1 Input Capture Pins
13.5.2 Input Capture/Output Compare Pin
13.5.3 Output Compare Pins
MC68HC16Y3/916Y3
USER’S MANUAL
The internal GPT interrupt priority hierarchy is shown in Table 13-2. The lower the in-
terrupt source number, the higher the priority. A single GPT interrupt source can be
given priority over all other GPT interrupt sources by assigning the priority adjust field
(IPA[3:0]) in the ICR a value equal to its source number.
Interrupt requests are asserted until associated status flags are cleared. Status flags
must be cleared in a particular sequence. The status register must first be read for set
flags, then zeros must be written to the flags that are to be cleared. If a new event oc-
curs between the time that the register is read and the time that it is written, the asso-
ciated flag is not cleared.
For more information on interrupts, refer to 5.8 Interrupts. For more information on on
exceptions, refer to 4.13.4 Types of Exceptions.
The GPT uses 12 of the MCU pins. Each pin can perform more than one function. De-
scriptions of GPT pins divided into functional groups follow.
Each input capture pin is associated with a single GPT input capture function. Each
pin has hysteresis. Any pulse longer than two system clocks is guaranteed to be valid
and any pulse shorter than one system clock is ignored. Each pin has an associated
16-bit capture register that holds the captured counter value. These pins can also be
used for general-purpose I/O. Refer to 13.8.2 Input Capture Functions for more
information.
The input capture/output compare pin can be configured for use by either an input cap-
ture or an output compare function. It has an associated 16-bit register that is used for
holding either the input capture value or the output match value. When used for input
capture the pin has the same hysteresis as other input capture pins. The pin can be
used for general-purpose I/O. Refer to 13.8.2 Input Capture Functions and 13.8.3 Out-
put Compare Functions for more information.
Output compare pins are used for GPT output compare functions. Each pin has an as-
sociated 16-bit compare register and a 16-bit comparator. Pins OC2, OC3, and OC4
are associated with a specific output compare function. The OC1 function can affect
the output of all compare pins. If the OC1 pin is not needed for an output compare func-
tion it can be used to output the clock selected for the timer counter register. Any of
these pins can also be used for general-purpose I/O. Refer to 13.8.3 Output Compare
Functions for more information.
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