PIC24FJ16MC101_12 Datasheet, PDF (172/350 Pages) Microchip Technology – 16-bit Microcontrollers (up to 32 KB Flash and 2 KB SRAM)

PIC24FJ16MC101/102 AND PIC24FJ32MC101/102/104
16.1 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
sync due to an errant SCK 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 SPI 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.
5. To avoid invalid slave read data to the master,
the user’s master software must guarantee
enough time for slave software to fill its write buf-
fer before the user application initiates a master
write/read cycle. It is always advisable to pre-
load the SPIxBUF transmit register in advance
of the next master transaction cycle. SPIxBUF is
transferred to the SPI shift register and is empty
once the data transmission begins.
16.2 SPI Resources
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 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=en554339
16.2.1 KEY RESOURCES
• Section 23. “Serial Peripheral Interface (SPI)”
(DS39699)
• Code Samples
• Application Notes
• Software Libraries
• Webinars
• All related PIC24F Family Reference Manual
sections
• Development Tools
DS39997C-page 172
Preliminary
© 2011-2012 Microchip Technology Inc.