Information

MSSP MODULE

4. Module: MSSP (I

C Mode)

The description of the I

C pins related to the TRIS

bits is clarified. To ensure proper communication of

the I

C Slave mode, the TRIS bits (TRISx [SDA,

SCL]) corresponding to the I

C pins must be set to

‘1’. If any TRIS bits (TRISx<7:0>) of the port con-

taining the I

C pins (PORTx [SDA, SCL]) are

changed in software during I

C communication

using a Read-Modify-Write instruction (BSF, BCF),

then the I

C mode may stop functioning properly

and I

C communication may suspend. Do not

change any of the TRISx bits (TRIS bits of the port

containing the I

C pins) using the instruction BSF

or BCF during I

C communication. If it is absolutely

necessary to change the TRISx bits during

communication, the following method can be

used:

Note: Item 4 applies to the Data Sheets for the

following devices:

• PIC16C717/770/771 (DS41120B)

• PIC16C773/774 (DS30275A)

• PIC16F872 (DS30221B)

• PIC16F873/874/876/877 (DS30292C)

• PIC16F873A/874A/876A/877A

(DS39582B)

MOVF TRISC, W ; Example for a 40-pin part such as the PIC16F877A

IORLW 0x18 ; Ensures <4:3> bits are ‘11’

ANDLW B’11111001’ ; Sets <2:1> as output, but will not alter other bits

; User can use their own logic here, such as IORLW, XORLW and ANDLW

MOVWF TRISC