Microchip Technology DM330023-2 Data Sheet

DS70283K-page 174

© 2007-2012 Microchip Technology Inc.

Many useful resources are provided on the main prod-
uct page of the Microchip web site for the devices listed
in this data sheet. This product page, which can be
accessed using this 

, contains the latest updates

and additional information.

16.1.1

KEY RESOURCES

• Section 15. “Quadrature Encoder Interface 

(QEI)” (DS70208)

• Code Samples
• Application Notes
• Software Libraries
• Webinars
• All related dsPIC33F/PIC24H Family Reference 

Manuals Sections

• Development Tools

The QEI module has four user-accessible registers,
accessible in either Byte or Word mode:
• Control/Status Register (QEICON) – Allows 

control of the QEI operation and status flags 
indicating the module state.

• Digital Filter Control Register (DFLTCON) – 

Allows control of the digital input filter operation.

• Position Count Register (POSCNT) – Allows 

reading and writing of the 16-bit position counter.

• Maximum Count Register (MAXCNT) – Holds a 

value that is compared to the POSCNT counter in 
some operations.

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The POSCNT register allows byte
accesses. However, reading the register
in Byte mode can result in partially
updated values in subsequent reads.
Either use Word mode reads/writes, or
ensure that the counter is not counting
during Byte operations.