Microchip Technology MA180025 Data Sheet

 2010 Microchip Technology Inc.

DS39933D-page 211

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 (I

2

C™)

- Full Master mode
- Slave mode (with general address call)

The I

2

C interface supports the following modes in

hardware:
• Master  mode
• Multi-Master mode
• Slave mode

Each MSSP module has three associated control
registers. These include a status register (SSPSTAT)
and two control registers (SSPCON1 and SSPCON2).
The use of these registers and their individual bits differ
significantly depending on whether the MSSP module
is operated in SPI or I

2

C mode.

Additional details are provided under the individual
sections.

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/SEG12
• Serial Data In (SDI) – RC4/SDI/SDA/SEG16
• Serial Clock (SCK) – RC3/SCK/SCL/SEG17 
Additionally, a fourth pin may be used when in a Slave
mode of operation:
• Slave Select (SS) – RF7/AN5/SS/SEG25
Figure 18-1 shows the block diagram of the MSSP
module when operating in SPI mode. 

(          )

Read

Write

Internal

Data Bus

SSPSR reg

SSPM<3:0>

bit 0

Shift

Clock

SS Control

Enable

Edge

Select

Clock Select

TMR2 Output

T

OSC

Prescaler

4, 16, 64

2

Edge

Select

2

4

Data to TXx/RXx in SSPSR

TRIS bit

2

SMP:CKE

SDO

SSPBUF reg

SDI

SS

SCK