DSPIC30F3011 Microchip Technology Inc., DSPIC30F3011 Datasheet - Page 80

• Manufacturer Part Number: DSPIC30F3011
• Description: Dspic30f3010/3011 Enhanced Flash 16-bit Digital Signal Controller
• Manufacturer: Microchip Technology Inc.

dsPIC30F3010/3011
12.1
The simple capture events in the dsPIC30F product
family are:
• Capture every falling edge
• Capture every rising edge
• Capture every 4th rising edge
• Capture every 16th rising edge
• Capture every rising and falling edge
These simple Input Capture modes are configured by
setting the appropriate bits ICM<2:0> (ICxCON<2:0>).
12.1.1
There are four input capture prescaler settings, speci-
fied by bits ICM<2:0> (ICxCON<2:0>). Whenever the
capture channel is turned off, the prescaler counter will
be cleared. In addition, any Reset will clear the
prescaler counter.
12.1.2
Each capture channel has an associated FIFO buffer,
which is four 16-bit words deep. There are two status
flags, which provide status on the FIFO buffer:
• ICBNE — Input Capture Buffer Not Empty
• ICOV — Input Capture Overflow
The ICBNE will be set on the first input capture event
and remain set until all capture events have been read
from the FIFO. As each word is read from the FIFO, the
remaining words are advanced by one position within
the buffer.
In the event that the FIFO is full with four capture
events and a fifth capture event occurs prior to a read
of the FIFO, an overflow condition will occur and the
ICOV bit will be set to a logic ‘1’. The fifth capture event
is lost and is not stored in the FIFO. No additional
events will be captured till all four events have been
read from the buffer.
If a FIFO read is performed after the last read and no
new capture event has been received, the read will
yield indeterminate results.
DS70141D-page 78
Simple Capture Event Mode
CAPTURE PRESCALER
CAPTURE BUFFER OPERATION
Confidential
12.1.3
Each capture channel can select between one of two
timers for the time base, Timer2 or Timer3.
Selection of the timer resource is accomplished
through SFR bit ICTMR (ICxCON<7>). Timer3 is the
default timer resource available for the input capture
module.
12.1.4
When the input capture module is set for capture on
every edge, rising and falling, ICM<2:0> = 001, the
following operations are performed by the input
capture logic:
• The input capture interrupt flag is set on every
• The interrupt on Capture Mode Setting bits,
• A capture overflow condition is not generated in
12.2
An input capture event will generate a device wake-up
or interrupt, if enabled, if the device is in CPU Idle or
Sleep mode.
Independent of the timer being enabled, the input
capture module will wake-up from the CPU Sleep or Idle
mode when a capture event occurs, if ICM<2:0> = 111
and the Interrupt Enable bit is asserted. The same
wake-up can generate an interrupt, if the conditions for
processing the interrupt have been satisfied. The wake-
up feature is useful as a method of adding extra external
pin interrupts.
12.2.1
CPU Sleep mode allows input capture module opera-
tion with reduced functionality. In the CPU Sleep
mode, the ICI<1:0> bits are not applicable, and the
input capture module can only function as an external
interrupt source.
The capture module must be configured for interrupt
only on the rising edge (ICM<2:0> = 111) in order for
the input capture module to be used while the device
is in Sleep mode. The prescale settings of 4:1 or 16:1
are not applicable in this mode.
edge, rising and falling.
ICI<1:0>, is ignored, since every capture
generates an interrupt.
this mode.
Input Capture Operation During
Sleep and Idle Modes
TIMER2 AND TIMER3 SELECTION
MODE
HALL SENSOR MODE
INPUT CAPTURE IN CPU SLEEP
MODE
© 2007 Microchip Technology Inc.