Si te referís a esta parte
SSPM<3:0>: Synchronous Serial Port Mode Select bits
0000 = SPI Master mode, clock = OSC/4
0001 = SPI Master mode, clock = OSC/16
0010 = SPI Master mode, clock = OSC/64
0011 = SPI Master mode, clock = TMR2 output/2
0100 = SPI Slave mode, clock = SCK pin. SS pin control enabled.
0101 = SPI Slave mode, clock = SCK pin. SS pin control disabled. SS can be used as I/O pin.
0110 = I2C Slave mode, 7-bit address
0111 = I2C Slave mode, 10-bit address
1011 = I2C Firmware Controlled Master mode (Slave Idle)
1110 = I2C Slave mode, 7-bit address with Start and Stop bit interrupts enabled
1111 = I2C Slave mode, 10-bit address with Start and Stop bit interrupts enabled
1000, 1001, 1010, 1100, 1101 = Reserved
el unico que puede trabajar en maestro es el SPI.
La unica opción de maestro para I2C es "I2C Firmware Controlled Master mode (Slave Idle)", pero no es parte del módulo SSP, hay que implementarla utilizando interrupciones,
AN554.
Saludos.