PIC18F-LF1XK50 MICROCHIP [Microchip Technology], PIC18F-LF1XK50 Datasheet - Page 171

• Manufacturer Part Number: PIC18F-LF1XK50
• Description: 20-Pin USB Flash Microcontrollers
• Manufacturer: MICROCHIP [Microchip Technology]

15.3.10
Transmission of a data byte, a 7-bit address or the
other half of a 10-bit address is accomplished by simply
writing a value to the SSPBUF register. This action will
set the Buffer Full flag bit, BF and allow the Baud Rate
Generator to begin counting and start the next trans-
mission. Each bit of address/data will be shifted out
onto the SDA pin after the falling edge of SCL is
asserted
parameter SP106). SCL is held low for one Baud Rate
Generator rollover count (T
before SCL is released high (see data setup time spec-
ification parameter SP107). When the SCL pin is
released high, it is held that way for T
the SDA pin must remain stable for that duration and
some hold time after the next falling edge of SCL. After
the eighth bit is shifted out (the falling edge of the eighth
clock), the BF flag is cleared and the master releases
SDA. This allows the slave device being addressed to
respond with an ACK bit during the ninth bit time if an
address match occurred, or if data was received prop-
erly. The status of ACK is written into the ACKDT bit on
the falling edge of the ninth clock. If the master receives
an
ACKSTAT, is cleared. If not, the bit is set. After the ninth
clock, the SSPIF bit is set and the master clock (Baud
Rate Generator) is suspended until the next data byte
is loaded into the SSPBUF, leaving SCL low and SDA
unchanged
After the write to the SSPBUF, each bit of the address
will be shifted out on the falling edge of SCL until all
seven address bits and the R/W bit are completed. On
the falling edge of the eighth clock, the master will
deassert the SDA pin, allowing the slave to respond
with an Acknowledge. On the falling edge of the ninth
clock, the master will sample the SDA pin to see if the
address was recognized by a slave. The status of the
ACK bit is loaded into the ACKSTAT status bit of the
SSPCON2 register. Following the falling edge of the
ninth clock transmission of the address, the SSPIF is
set, the BF flag is cleared and the Baud Rate Generator
is turned off until another write to the SSPBUF takes
place, holding SCL low and allowing SDA to float.
15.3.10.1
In Transmit mode, the BF bit of the SSPSTAT register
is set when the CPU writes to SSPBUF and is cleared
when all 8 bits are shifted out.
15.3.10.2
If the user writes the SSPBUF when a transmit is
already in progress (i.e., SSPSR is still shifting out a
data byte), the WCOL is set and the contents of the buf-
fer are unchanged (the write doesn’t occur).
WCOL must be cleared by software before the next
transmission.
 2010 Microchip Technology Inc.
Acknowledge,
I
TRANSMISSION
(see
(Figure
2
C MASTER MODE
BF Status Flag
WCOL Status Flag
data
15-21).
the Acknowledge
hold
BRG
). Data should be valid
time
BRG
. The data on
specification
Status bit,
Preliminary
15.3.10.3
In Transmit mode, the ACKSTAT bit of the SSPCON2
register is cleared when the slave has sent an Acknowl-
edge (ACK = 0) and is set when the slave does not
Acknowledge (ACK = 1). A slave sends an Acknowl-
edge when it has recognized its address (including a
general call), or when the slave has properly received
its data.
15.3.11
Master mode reception is enabled by programming the
Receive Enable bit, RCEN bit of the SSPCON2
register.
The Baud Rate Generator begins counting and on each
rollover,
(high-to-low/low-to-high) and data is shifted into the
SSPSR. After the falling edge of the eighth clock, the
receive enable flag is automatically cleared, the con-
tents of the SSPSR are loaded into the SSPBUF, the
BF flag bit is set, the SSPIF flag bit is set and the Baud
Rate Generator is suspended from counting, holding
SCL low. The MSSP is now in Idle state awaiting the
next command. When the buffer is read by the CPU,
the BF flag bit is automatically cleared. The user can
then send an Acknowledge bit at the end of reception
by setting the Acknowledge Sequence Enable, ACKEN
bit of the SSPCON2 register.
15.3.11.1
In receive operation, the BF bit is set when an address
or data byte is loaded into SSPBUF from SSPSR. It is
cleared when the SSPBUF register is read.
15.3.11.2
In receive operation, the SSPOV bit is set when 8 bits
are received into the SSPSR and the BF flag bit is
already set from a previous reception.
15.3.11.3
If the user writes the SSPBUF when a receive is
already in progress (i.e., SSPSR is still shifting in a data
byte), the WCOL bit is set and the contents of the buffer
are unchanged (the write doesn’t occur).
Note:
PIC18F/LF1XK50
the
I
The MSSP module must be in an Idle
state before the RCEN bit is set or the
RCEN bit will be disregarded.
2
ACKSTAT Status Flag
C MASTER MODE RECEPTION
BF Status Flag
SSPOV Status Flag
WCOL Status Flag
state
of
the
SCL
DS41350E-page 171
pin
changes