MA180025 Microchip Technology, MA180025 Datasheet - Page 215

• 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

18.3.3
To enable the serial port, the MSSP Enable bit, SSPEN
(SSPCON1<5>), must be set. To reset or reconfigure
SPI mode, clear the SSPEN bit, reinitialize the
SSPCON registers and then set the SSPEN bit. This
configures the SDI, SDO, SCK and SS pins as serial
port pins. For the pins to behave as the serial port func-
tion, some must have their data direction bits (in the
TRIS register) appropriately programmed as follows:
• SDI is automatically controlled by the SPI module
• SDO must have TRISC<5> bit cleared
• SCK (Master mode) must have TRISC<3> bit
• SCK (Slave mode) must have TRISC<3> bit set
• SS must have TRISF<7> bit set
Any serial port function that is not desired may be
overridden by programming the corresponding data
direction (TRIS) register to the opposite value.
18.3.4
The drivers for the SDO output and SCK clock pins can
be optionally configured as open-drain outputs. This
feature allows the voltage level on the pin to be pulled
FIGURE 18-2:
 2010 Microchip Technology Inc.
cleared
ENABLING SPI I/O
OPEN-DRAIN OUTPUT OPTION
SPI Master SSPM<3:0> =
MSb
PROCESSOR 1
Serial Input Buffer
SPI MASTER/SLAVE CONNECTION
Shift Register
(SSPBUF)
(SSPSR)
00xx
LSb
SDO
SCK
SDI
Serial Clock
PIC18F87J90 FAMILY
to a higher level through an external pull-up resistor,
and allows the output to communicate with external
circuits without the need for additional level shifters.
The open-drain output option is controlled by the
SPIOD bit (TRISG<7>). Setting this bit configures both
pins for open-drain operation.
18.3.5
Figure 18-2 shows a typical connection between two
microcontrollers. The master controller (Processor 1)
initiates the data transfer by sending the SCK signal.
Data is shifted out of both shift registers on their pro-
grammed clock edge and latched on the opposite edge
of the clock. Both processors should be programmed to
the same Clock Polarity (CKP), then both controllers
would send and receive data at the same time.
Whether the data is meaningful (or dummy data)
depends on the application software. This leads to
three scenarios for data transmission:
• Master sends data–Slave sends dummy data
• Master sends data–Slave sends data
• Master sends dummy data–Slave sends data
SDO
SCK
SDI
TYPICAL CONNECTION
SPI Slave SSPM<3:0> =
MSb
Serial Input Buffer
Shift Register
PROCESSOR 2
(SSPBUF)
(SSPSR)
LSb
DS39933D-page 215
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