PIC18F2221_1 Datasheet, PDF (167/402 Pages) Microchip Technology – Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology

PIC18F2221/2321/4221/4321 FAMILY
18.0 MASTER SYNCHRONOUS
SERIAL PORT (MSSP)
MODULE
18.1 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,
display 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 address masking for both
10-bit and 7-bit addressing)
The I²C interface supports the following modes in
hardware:
• Master mode
• Multi-Master mode
• Slave mode
18.2 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.
18.3 SPI Mode
The SPI mode allows 8 bits of data to be synchronously
transmitted and received simultaneously. All four SPI
modes are supported. To accomplish communication,
typically three pins are used:
• Serial Data Out (SDO) – SDO
• Serial Data In (SDI) – SDI/SDA
• Serial Clock (SCK) – SCK/SCL
Additionally, a fourth pin may be used when in a Slave
mode of operation:
• Slave Select (SS)
Figure 18-1 shows the block diagram of the MSSP
module when operating in SPI mode.
FIGURE 18-1:
MSSP BLOCK DIAGRAM
(SPI MODE)
Internal
Data Bus
Read
Write
SSPBUF reg
SDI/SDA
SDO
SSPSR reg
bit 0
Shift
Clock
SS
SCK/SCL
SS Control
Enable
Edge
Select
2
Clock Select
SSPM<3:0>
SMP:CKE ₄
2
( ) TMR2 Output
2
Edge
Select
Prescaler TOSC
4, 16, 64
Data to TX/RX in SSPSR
TRIS bit
© 2009 Microchip Technology Inc.
DS39689F-page 167