Microchip Technology DM164134 Scheda Tecnica

© 2006 Microchip Technology Inc.

DS41159E-page 143

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

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 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 

• 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) – RA5/AN4/SS/LVDIN

Figure 17-1 shows the block diagram of the MSSP
module when operating in SPI mode. 

(          )

Read

Write

Internal

Data Bus

SSPSR reg

SSPM3:SSPM0

bit0

Shift

Clock

SS Control

Enable

Edge

Select

Clock Select

TMR2 Output

T

OSC

Prescaler

4, 16, 64

2

Edge

Select

2

4

Data to TX/RX in SSPSR

TRIS bit

2

SMP:CKE

RC5/SDO

SSPBUF reg

RC4/SDI/SDA

RA5/AN4/

RC3/SCK/

SCL

SS/LVDIN