DSPIC30F2012 Microchip Technology Inc., DSPIC30F2012 Datasheet - Page 84

• Manufacturer Part Number: DSPIC30F2012
• Description: Dspic30f2011/2012/3012/3013 High-performance Digital Signal Controllers
• Manufacturer: Microchip Technology Inc.

dsPIC30F2011/2012/3012/3013
11.1.2
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 is set on the first input capture event and
remains 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 occurs and the ICOV
bit is set to a logic ‘1’. The fifth capture event is lost and
is not stored in the FIFO. No additional events are cap-
tured until 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.
11.1.3
The input capture module consists of up to 8 input cap-
ture channels. Each 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.
11.1.4
When the input capture module is set for capture on
every edge, rising and falling, ICM<2:0> = 001, the fol-
lowing 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
DS70139E-page 82
edge, rising and falling.
ICI<1:0>, is ignored since every capture
generates an interrupt.
this mode.
CAPTURE BUFFER OPERATION
TIMER2 AND TIMER3 SELECTION
MODE
HALL SENSOR MODE
11.2
An input capture event generates 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 cap-
ture module wakes 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 inter-
rupts.
11.2.1
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 cap-
ture module can only function as an external interrupt
source.
The capture module must be configured for interrupt
only on 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.
11.2.2
CPU Idle mode allows input capture module operation
with full functionality. In the CPU Idle mode, the Inter-
rupt mode selected by the ICI<1:0> bits is applicable,
as well as the 4:1 and 16:1 capture prescale settings
which are defined by control bits ICM<2:0>. This mode
requires the selected timer to be enabled. Moreover,
the ICSIDL bit must be asserted to a logic ‘0’.
If
ICM<2:0> = 111 in CPU Idle mode, the input capture
pin serves only as an external interrupt pin.
11.3
The input capture channels have the ability to generate
an interrupt based upon the selected number of cap-
ture events. The selection number is set by control bits,
ICI<1:0> (ICxCON<6:5>).
Each channel provides an interrupt flag (ICxIF) bit. The
respective capture channel interrupt flag is located in
the corresponding IFSx register.
Enabling an interrupt is accomplished via the respec-
tive capture channel interrupt enable (ICxIE) bit. The
capture interrupt enable bit is located in the
corresponding IEC Control register.
the
Input Capture Operation During
Sleep and Idle Modes
Input Capture Interrupts
input
INPUT CAPTURE IN CPU SLEEP
MODE
INPUT CAPTURE IN CPU IDLE
MODE
capture
© 2006 Microchip Technology Inc.
module
is
defined
as