PIC18F23K22 Datasheet, PDF (232/492 Pages) Microchip Technology – 28/40/44-Pin, Low-Power, High-Performance Microcontrollers with nanoWatt XLP Technology

PIC18(L)F2X/4XK22
15.5.4 SLAVE MODE 10-BIT ADDRESS
RECEPTION
This section describes a standard sequence of events
for the MSSPx module configured as an I²C slave in
10-bit Addressing mode.
Figure 15-19 and is used as a visual reference for this
description.
This is a step by step process of what must be done by
slave software to accomplish I²C communication.
1. Bus starts Idle.
2. Master sends Start condition; S bit of SSPxSTAT
is set; SSPxIF is set if interrupt on Start detect is
enabled.
3. Master sends matching high address with R/W
bit clear; UA bit of the SSPxSTAT register is set.
4. Slave sends ACK and SSPxIF is set.
5. Software clears the SSPxIF bit.
6. Software reads received address from SSPxBUF
clearing the BF flag.
7. Slave loads low address into SSPxADD,
releasing SCLx.
8. Master sends matching low address byte to the
slave; UA bit is set.
Note: Updates to the SSPxADD register are not
allowed until after the ACK sequence.
9. Slave sends ACK and SSPxIF is set.
Note: If the low address does not match, SSPxIF
and UA are still set so that the slave software
can set SSPxADD back to the high address.
BF is not set because there is no match.
CKP is unaffected.
10. Slave clears SSPxIF.
11. Slave reads the received matching address
from SSPxBUF clearing BF.
12. Slave loads high address into SSPxADD.
13. Master clocks a data byte to the slave and clocks
out the slaves ACK on the 9th SCLx pulse;
SSPxIF is set.
14. If SEN bit of SSPxCON2 is set, CKP is cleared
by hardware and the clock is stretched.
15. Slave clears SSPxIF.
16. Slave reads the received byte from SSPxBUF
clearing BF.
17. If SEN is set the slave sets CKP to release the
SCLx.
18. Steps 13-17 repeat for each received byte.
19. Master sends Stop to end the transmission.
15.5.5 10-BIT ADDRESSING WITH ADDRESS OR
DATA HOLD
Reception using 10-bit addressing with AHEN or
DHEN set is the same as with 7-bit modes. The only
difference is the need to update the SSPxADD register
using the UA bit. All functionality, specifically when the
CKP bit is cleared and SCLx line is held low are the
same. Figure 15-20 can be used as a reference of a
slave in 10-bit addressing with AHEN set.
Figure 15-21 shows a standard waveform for a slave
transmitter in 10-bit Addressing mode.
DS41412B-page 232
Preliminary
 2010 Microchip Technology Inc.