PIC18F4550-I/PT Microchip Technology Inc., PIC18F4550-I/PT Datasheet - Page 232

• Manufacturer Part Number: PIC18F4550-I/PT
• Description: 44 PIN, 32 KB FLASH, 2048 RAM, FS-USB 2.0
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F4550-I/PT

• A/d Inputs: 13-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 12 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 34
• Interface: I2C/SPI/UART/USART/USB
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 44-pin TQFP
• Programmable Memory: 32K Bytes
• Ram Size: 2K Bytes
• Speed: 48 MHz
• Timers: 1-8-bit, 3-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIC18F2455/2550/4455/4550
19.4.12
An Acknowledge sequence is enabled by setting the
Acknowledge
(SSPCON2<4>). When this bit is set, the SCL pin is
pulled low and the contents of the Acknowledge data bit
are presented on the SDA pin. If the user wishes to gen-
erate an Acknowledge, then the ACKDT bit should be
cleared. If not, the user should set the ACKDT bit before
starting an Acknowledge sequence. The Baud Rate
Generator then counts for one rollover period (T
and the SCL pin is deasserted (pulled high). When the
SCL pin is sampled high (clock arbitration), the Baud
Rate Generator counts for T
pulled low. Following this, the ACKEN bit is automatically
cleared, the Baud Rate Generator is turned off and the
MSSP module then goes into an inactive state
(Figure 19-25).
19.4.12.1
If the user writes the SSPBUF when an Acknowledge
sequence is in progress, then WCOL is set and the
contents of the buffer are unchanged (the write doesn’t
occur).
FIGURE 19-25:
FIGURE 19-26:
DS39632C-page 230
ACKNOWLEDGE SEQUENCE
TIMING
WCOL Status Flag
Note: T
SSPIF
Note: T
SCL
SDA
Sequence
SDA
Acknowledge sequence starts here,
SCL
Write to SSPCON2,
Falling edge of
ninth clock
BRG
BRG
ACKNOWLEDGE SEQUENCE WAVEFORM
STOP CONDITION RECEIVE OR TRANSMIT MODE
= one Baud Rate Generator period.
= one Baud Rate Generator period.
ACKEN = 1, ACKDT = 0
Set SSPIF at the
end of receive
BRG
ACK
set PEN
Enable
write to SSPCON2
. The SCL pin is then
SDA asserted low before rising edge of clock
to setup Stop condition
bit,
8
D0
T
T
BRG
BRG
ACKEN
BRG
Preliminary
T
SCL brought high after T
BRG
)
Cleared in
software
T
BRG
P
ACK
SCL = 1 for T
after SDA sampled high. P bit (SSPSTAT<4>) is set.
T
BRG
19.4.13
A Stop bit is asserted on the SDA pin at the end of a
receive/transmit by setting the Stop Enable bit, PEN
(SSPCON2<2>). At the end of a receive/transmit, the
SCL line is held low after the falling edge of the ninth
clock. When the PEN bit is set, the master will assert
the SDA line low. When the SDA line is sampled low,
the Baud Rate Generator is reloaded and counts down
to ‘0’. When the Baud Rate Generator times out, the
SCL pin will be brought high and one T
Generator rollover count) later, the SDA pin will be
deasserted. When the SDA pin is sampled high while
SCL is high, the P bit (SSPSTAT<4>) is set. A T
later, the PEN bit is cleared and the SSPIF bit is set
(Figure 19-26).
19.4.13.1
If the user writes the SSPBUF when a Stop sequence
is in progress, then the WCOL bit is set and the
contents of the buffer are unchanged (the write doesn’t
occur).
T
BRG
Set SSPIF at the end
of Acknowledge sequence
9
PEN bit (SSPCON2<2>) is cleared by
hardware and the SSPIF bit is set
BRG
BRG
, followed by SDA = 1 for T
STOP CONDITION TIMING
ACKEN automatically cleared
WCOL Status Flag
Cleared in
software
© 2006 Microchip Technology Inc.
BRG
BRG
(Baud Rate
BRG