PIC24EP256GU810-I Datasheet, PDF (338/622 Pages) Electronic Film Capacitors, Inc. – 16-Bit Microcontrollers and Digital Signal Controllers with High-Speed PWM, USB and Advanced Analog

dsPIC33EPXXX(GP/MC/MU)806/810/814 and PIC24EPXXX(GP/GU)810/814
18.1 SPI Helpful Tips
1. In Frame mode, if there is a possibility that the
master may not be initialized before the slave:
a) If FRMPOL (SPIxCON2<13>) = 1, use a
pull-down resistor on SSx.
b) If FRMPOL = 0, use a pull-up resistor on
SSx.
Note:
This insures that the first frame
transmission after initialization is not
shifted or corrupted.
2. In Non-Framed 3-Wire mode, (i.e., not using
SSx from a master):
a) If CKP (SPIxCON1<6>) = 1, always place a
pull-up resistor on SSx.
b) If CKP = 0, always place a pull-down
resistor on SSx.
Note:
This will insure that during power-up and
initialization, the master/slave will not lose
synchronization due to an errant SCKx
transition that would cause the slave to
accumulate data shift errors, for both
transmit and receive, appearing as
corrupted data.
3. FRMEN (SPIxCON2<15>) = 1 and SSEN
(SPIxCON1<7>) = 1 are exclusive and invalid.
In Frame mode, SCKx is continuous and the
Frame Sync pulse is active on the SSx pin,
which indicates the start of a data frame.
Note:
Not all third-party devices support Frame
mode timing. Refer to the SPIx electrical
characteristics for details.
4. In Master mode only, set the SMP bit
(SPIxCON1<9>) to a ‘1’ for the fastest SPI data
rate possible. The SMP bit can only be set at the
same time or after the MSTEN bit
(SPIxCON1<5>) is set.
To avoid invalid slave read data to the master, the
user’s master software must ensure enough time for
slave software to fill its write buffer before the user
application initiates a master write/read cycle. It is
always advisable to preload the SPIxBUF Transmit
register in advance of the next master transaction
cycle. SPIxBUF is transferred to the SPIx Shift register
and is empty once the data transmission begins.
18.2 SPI Resources
Many useful resources related to SPI are provided on
the main product page of the Microchip web site for the
devices listed in this data sheet. This product page,
which can be accessed using this link, contains the
latest updates and additional information.
Note:
In the event you are not able to access the
product page using the link above, enter
this URL in your browser:
http://www.microchip.com/wwwproducts/
Devices.aspx?dDocName=en554301
18.2.1 KEY RESOURCES
• Section 18. “Serial Peripheral Interface (SPI)”
(DS70569) in the “dsPIC33E/PIC24E Family
Reference Manual”
• Code Samples
• Application Notes
• Software Libraries
• Webinars
• All related “dsPIC33E/PIC24E Family Reference
Manual” Sections
• Development Tools
DS70616G-page 338
 2009-2012 Microchip Technology Inc.