PIC16F/LF1946/47
23.5.4 SLAVE MODE 10-BIT ADDRESS
RECEPTION
23.5.5 10-BIT ADDRESSING WITH ADDRESS OR
DATA HOLD
This section describes a standard sequence of events
for the MSSPx module configured as an I2C Slave in
10-bit Addressing mode.
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 23-20 can be used as a reference of a
slave in 10-bit addressing with AHEN set.
Figure 23-19 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.
Figure 23-21 shows a standard waveform for a slave
transmitter in 10-bit Addressing mode.
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.
DS41414A-page 260
Preliminary
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