DSPIC30F3010_13 Datasheet, PDF (94/228 Pages) Microchip Technology – High-Performance,16-Bit Digital Signal Controllers

dsPIC30F3010/3011
14.7 QEI Module Operation During CPU
Idle Mode
Since the QEI module can function as a Quadrature
Encoder Interface, or as a 16-bit timer, the following
section describes operation of the module in both
modes.
14.7.1 QEI OPERATION DURING CPU IDLE
MODE
When the CPU is placed in the Idle mode, the QEI
module will operate if the QEISIDL bit
(QEICON<13>) = 0. This bit defaults to a logic ‘0’
upon executing POR and BOR. For halting the QEI
module during the CPU Idle mode, QEISIDL should
be set to ‘1’.
14.7.2 TIMER OPERATION DURING CPU
IDLE MODE
When the CPU is placed in the Idle mode and the QEI
module is configured in the 16-Bit Timer mode, the
16-bit timer will operate if the QEISIDL bit (QEI-
CON<13>) = 0. This bit defaults to a logic ‘0’ upon
executing POR and BOR. For halting the timer module
during the CPU Idle mode, QEISIDL should be set
to ‘1’.
If the QEISIDL bit is cleared, the timer will function
normally as if the CPU Idle mode had not been
entered.
14.8 Quadrature Encoder Interface
Interrupts
The Quadrature Encoder Interface has the ability to
generate an interrupt on occurrence of the following
events:
• Interrupt on 16-bit up/down position counter
rollover/underflow
• Detection of qualified index pulse, or if CNTERR
bit is set
• Timer period match event (overflow/underflow)
• Gate accumulation event
The QEI Interrupt Flag bit, QEIIF, is asserted upon
occurrence of any of the above events. The QEIIF bit
must be cleared in software. QEIIF is located in the
IFS2 register.
Enabling an interrupt is accomplished through the
respective enable bit, QEIIE. The QEIIE bit is located in
the IEC2 register.
DS70141F-page 94
© 2010 Microchip Technology Inc.