PIC16LF18854 Datasheet, PDF (481/668 Pages) Microchip Technology – C Compiler Optimized RISC Architecture

PIC16(L)F18856/76
31.5.3.3 7-bit Transmission with Address
Hold Enabled
Setting the AHEN bit of the SSPxCON3 register
enables additional clock stretching and interrupt
generation after the eighth falling edge of a received
matching address. Once a matching address has
been clocked in, CKP is cleared and the SSPxIF
interrupt is set.
Figure 31-19 displays a standard waveform of a 7-bit
address slave transmission with AHEN enabled.
1. Bus starts Idle.
2. Master sends Start condition; the S bit of
SSPxSTAT is set; SSPxIF is set if interrupt on
Start detect is enabled.
3. Master sends matching address with R/W bit
set. After the eighth falling edge of the SCL line
the CKP bit is cleared and SSPxIF interrupt is
generated.
4. Slave software clears SSPxIF.
5. Slave software reads ACKTIM bit of SSPxCON3
register, and R/W and D/A of the SSPxSTAT
register to determine the source of the interrupt.
6. Slave reads the address value from the
SSPxBUF register clearing the BF bit.
7. Slave software decides from this information if it
wishes to ACK or not ACK and sets the ACKDT
bit of the SSPxCON2 register accordingly.
8. Slave sets the CKP bit releasing SCL.
9. Master clocks in the ACK value from the slave.
10. Slave hardware automatically clears the CKP bit
and sets SSPxIF after the ACK if the R/W bit is
set.
11. Slave software clears SSPxIF.
12. Slave loads value to transmit to the master into
SSPxBUF setting the BF bit.
Note: SSPxBUF cannot be loaded until after the
ACK.
13. Slave sets the CKP bit releasing the clock.
14. Master clocks out the data from the slave and
sends an ACK value on the ninth SCL pulse.
15. Slave hardware copies the ACK value into the
ACKSTAT bit of the SSPxCON2 register.
16. Steps 10-15 are repeated for each byte transmit-
ted to the master from the slave.
17. If the master sends a not ACK the slave
releases the bus allowing the master to send a
Stop and end the communication.
Note: Master must send a not ACK on the last
byte to ensure that the slave releases the
SCL line to receive a Stop.
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Preliminary
DS40001824A-page 481