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SPI and I2C (MSSP)

The MSSP (Master Synchronous Serial Port) module supports SPI and I2C.

SPI (Serial Peripheral Interface)

Master generates clock (SCK)
Lines: SDO, SDI, SCK, SS (chip select)
Full duplex, synchronous
Used with serial EEPROMs, displays, sensors

SPI master mode waveforms on the PIC18F4550 — SPI master waveforms: relationship between SCK, SDO, SDI and CKP, CKE, SMP bits. — Microchip PIC18F4550 Datasheet — FIGURE 19-3

SPI mode table and MSSP registers — Standard SPI modes (CKP/CKE) and related registers: SSPCON1, SSPSTAT, SSPBUF. — Microchip PIC18F4550 Datasheet — TABLE 19-1 and 19-2

I2C (Inter-Integrated Circuit)

Two wires: SDA (data), SCL (clock)
Modes: Master, Multi-Master, Slave
7- or 8-bit device addressing
Used with sensors, RTC, memories

I2C slave mode timing on the PIC18F4550 — I2C slave timing: address sequence, read/write, and ACK. — Microchip PIC18F4550 Datasheet — FIGURE 19-8

MSSP registers

SSPCON1, SSPCON2 — control
SSPSTAT — status
SSPBUF — data buffer
SSPADD — I2C address (slave mode)

See the datasheet for detailed configuration tables.

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