MA180025 Microchip Technology, MA180025 Datasheet - Page 214

• Manufacturer Part Number: MA180025
• Description: MODULE PLUG-IN PIC18F87J90 PIM
• Manufacturer: Microchip Technology
• Series: PIC®r

Specifications of MA180025

• Accessory Type: Plug-In Module (PIM) - PIC18F87J90
• Product: Microcontroller Modules
• Silicon Manufacturer: Microchip
• Core Architecture: PIC
• Core Sub-architecture: PIC18
• Silicon Core Number: PIC18F
• Silicon Family Name: PIC18FxxJxx
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: PICDEM LCD 2 Demonstration Board (DM163030)
• For Use With: DM163030 - KIT DEV PICDEM LCD2
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PIC18F87J90 FAMILY
18.3.2
When initializing the SPI, several options need to be
specified. This is done by programming the appropriate
control bits (SSPCON1<5:0> and SSPSTAT<7:6>).
These control bits allow the following to be specified:
• Master mode (SCK is the clock output)
• Slave mode (SCK is the clock input)
• Clock Polarity (Idle state of SCK)
• Data Input Sample Phase (middle or end of data
• Clock Edge (output data on rising/falling edge of
• Clock Rate (Master mode only)
• Slave Select mode (Slave mode only)
Each MSSP consists of a transmit/receive shift register
(SSPSR) and a buffer register (SSPBUF). The SSPSR
shifts the data in and out of the device, MSb first. The
SSPBUF holds the data that was written to the SSPSR
until the received data is ready. Once the 8 bits of data
have been received, that byte is moved to the SSPBUF
register. Then, the Buffer Full detect bit, BF
(SSPSTAT<0>), and the interrupt flag bit, SSPIF, are
set. This double-buffering of the received data
(SSPBUF) allows the next byte to start reception before
EXAMPLE 18-1:
DS39933D-page 214
LOOP
output time)
SCK)
BTFSS
BRA
MOVF
MOVWF
MOVF
MOVWF
OPERATION
SSPSTAT, BF
LOOP
SSPBUF, W
RXDATA
TXDATA, W
SSPBUF
LOADING THE SSPBUF (SSPSR) REGISTER
;Has data been received (transmit complete)?
;No
;WREG reg = contents of SSPBUF
;Save in user RAM, if data is meaningful
;W reg = contents of TXDATA
;New data to xmit
SSPBUF has been loaded with the received data (trans-
reading the data that was just received. Any write to the
SSPBUF register during transmission/reception of data
will be ignored and the Write Collision detect bit, WCOL
(SSPCON1<7>), will be set. User software must clear
the WCOL bit so that it can be determined if the following
write(s) to the SSPBUF register completed successfully.
When the application software is expecting to receive
valid data, the SSPBUF should be read before the next
byte of data to transfer is written to the SSPBUF. The
Buffer Full bit, BF (SSPSTAT<0>), indicates when
mission is complete). When the SSPBUF is read, the BF
bit is cleared. This data may be irrelevant if the SPI is
only a transmitter. Generally, the MSSP interrupt is used
to determine when the transmission/reception has com-
pleted. The SSPBUF must be read and/or written. If the
interrupt method is not going to be used, then software
polling can be done to ensure that a write collision does
not occur. Example 18-1 shows the loading of the
SSPBUF (SSPSR) for data transmission.
The SSPSR is not directly readable or writable and can
only be accessed by addressing the SSPBUF register.
Additionally, the SSPSTAT register indicates the
various status conditions.
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