PIC12F1822 MICROCHIP [Microchip Technology], PIC12F1822 Datasheet - Page 242

• Manufacturer Part Number: PIC12F1822
• Description: 8/14-Pin Flash Microcontrollers with nanoWatt XLP Technology
• Manufacturer: MICROCHIP [Microchip Technology]

PIC12F/LF1822/16F/LF1823
24.5.2
When the R/W bit of a matching received address byte
is clear, the R/W bit of the SSP1STAT register is
cleared. The received address is loaded into the
SSP1BUF register and acknowledged.
When the overflow condition exists for a received
address, then not Acknowledge is given. An overflow
condition is defined as either bit BF of the SSP1STAT
register is set, or bit SSP1OV of the SSP1CON1 regis-
ter is set. The BOEN bit of the SSP1CON3 register
modifies this operation. For more information see
Register 24-4.
An MSSP1 interrupt is generated for each transferred
data byte. Flag bit, SSP1IF, must be cleared by soft-
ware.
When the SEN bit of the SSP1CON2 register is set,
SCL will be held low (clock stretch) following each
received byte. The clock must be released by setting
the CKP bit of the SSP1CON1 register, except
sometimes in 10-bit mode. See Section 24.2.3 “SPI
Master Mode” for more detail.
24.5.2.1
This section describes a standard sequence of events
for the MSSP1 module configured as an I
7-bit Addressing mode. All decisions made by hard-
ware or software and their effect on reception.
Figure 24-13 and Figure 24-14 is used as a visual
reference for this description.
This is a step by step process of what typically must
be done to accomplish I
1.
2.
3.
4.
5.
6.
7.
8.
9.
10. Software clears SSP1IF.
11. Software
12. Steps 8-12 are repeated for all received bytes
13. Master sends Stop condition, setting P bit of
DS41413A-page 242
Start bit detected.
S bit of SSP1STAT is set; SSP1IF is set if inter-
rupt on Start detect is enabled.
Matching address with R/W bit clear is received.
The slave pulls SDA low sending an ACK to the
master, and sets SSP1IF bit.
Software clears the SSP1IF bit.
Software
SSP1BUF clearing the BF flag.
If SEN = 1; Slave software sets CKP bit to
release the SCL line.
The master clocks out a data byte.
Slave drives SDA low sending an ACK to the
master, and sets SSP1IF bit.
SSP1BUF clearing BF.
from the Master.
SSP1STAT, and the bus goes idle.
SLAVE RECEPTION
7-bit Addressing Reception
reads
reads
2
the
C communication.
received
received
address
byte
2
C Slave in
from
from
Preliminary
24.5.2.2
Slave device reception with AHEN and DHEN set
operate the same as without these options with extra
interrupts and clock stretching added after the 8th fall-
ing edge of SCL. These additional interrupts allow the
slave software to decide whether it wants to ACK the
receive address or data byte, rather than the hard-
ware. This functionality adds support for PMBus™ that
was not present on previous versions of this module.
This list describes the steps that need to be taken by
slave software to use these options for I
cation. Figure 24-15 displays a module using both
address and data holding. Figure 24-16 includes the
operation with the SEN bit of the SSP1CON2 register
set.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10. Slave clears SSP1IF.
11. SSP1IF set and CKP cleared after 8th falling
12. Slave looks at ACKTIM bit of SSP1CON3 to
13. Slave reads the received data from SSP1BUF
14. Steps 7-14 are the same for each received data
15. Communication is ended by either the slave
Note: SSP1IF is still set after the 9th falling edge of
S bit of SSP1STAT is set; SSP1IF is set if inter-
rupt on Start detect is enabled.
Matching address with R/W bit clear is clocked
in. SSP1IF is set and CKP cleared after the 8th
falling edge of SCL.
Slave clears the SSP1IF.
Slave can look at the ACKTIM bit of the
SSP1CON3 register to determine if the SSP1IF
was after or before the ACK.
Slave reads the address value from SSP1BUF,
clearing the BF flag.
Slave sets ACK value clocked out to the master
by setting ACKDT.
Slave releases the clock by setting CKP.
SSP1IF is set after an ACK, not after a NACK.
If SEN = 1 the slave hardware will stretch the
clock after the ACK.
edge of SCL for a received data byte.
determine the source of the interrupt.
clearing BF.
byte.
sending an ACK = 1, or the master sending a
Stop condition. If a Stop is sent and Interrupt on
Stop Detect is disabled, the slave will only know
by polling the P bit of the SSTSTAT register.
SCL even if there is no clock stretching and
BF has been cleared. Only if NACK is sent to
Master is SSP1IF not set
7-bit Reception with AHEN and DHEN
 2010 Microchip Technology Inc.
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C commun-