PIC18F6520-I Datasheet, PDF (159/380 Pages) Micrel Semiconductor – 64/80-Pin High-Performance, 256 Kbit to 1 Mbit Enhanced Flash Microcontrollers with A/D

PIC18F6520/8520/6620/8620/6720/8720
17.0 MASTER SYNCHRONOUS
SERIAL PORT (MSSP)
MODULE
17.1 Master SSP (MSSP) Module
Overview
The Master Synchronous Serial Port (MSSP) module is
a serial interface, useful for communicating with other
peripheral or microcontroller devices. These peripheral
devices may be serial EEPROMs, shift registers, dis-
play drivers, A/D converters, etc. The MSSP module
can operate in one of two modes:
• Serial Peripheral Interface (SPI)
• Inter-Integrated Circuit (I²C)
- Full Master mode
- Slave mode (with general address call)
The I²C interface supports the following modes in
hardware:
• Master mode
• Multi-Master mode
• Slave mode
17.2 Control Registers
The MSSP module has three associated registers.
These include a status register (SSPSTAT) and two
control registers (SSPCON1 and SSPCON2). The use
of these registers and their individual configuration bits
differ significantly, depending on whether the MSSP
module is operated in SPI or I²C mode.
Additional details are provided under the individual
sections.
17.3 SPI Mode
The SPI mode allows 8 bits of data to be synchronously
transmitted and received simultaneously. All four modes
of SPI are supported. To accomplish communication,
typically three pins are used:
• Serial Data Out (SDO) – RC5/SDO
• Serial Data In (SDI) – RC4/SDI/SDA
• Serial Clock (SCK) – RC3/SCK/SCL
Additionally, a fourth pin may be used when in a Slave
mode of operation:
• Slave Select (SS) – RF7/SS
Figure 17-1 shows the block diagram of the MSSP
module when operating in SPI mode.
FIGURE 17-1:
MSSP BLOCK DIAGRAM
(SPI MODE)
Internal
Data Bus
Read
Write
SSPBUF reg
RC4/SDI/SDA
RC5/SDO
SSPSR reg
bit0
Shift
Clock
RF7/SS
RC3/SCK/
SCL
SS Control
Enable
Edge
Select
2
Clock Select
SSPM3:SSPM0
SMP:CKE ₄
2
( ) TMR2 Output
2
Edge
Select
Prescaler TOSC
4, 16, 64
Data to TX/RX in SSPSR
TRIS bit
 2004 Microchip Technology Inc.
DS39609B-page 157