PIC18F4550-I/P Microchip Technology Inc., PIC18F4550-I/P Datasheet - Page 209

• Manufacturer Part Number: PIC18F4550-I/P
• Description: 40 PIN, 32 KB FLASH, 2048 RAM, FS-USB 2.0
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F4550-I/P

• 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: 40-pin PDIP
• 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

19.4.2
The MSSP module functions are enabled by setting
MSSP Enable bit, SSPEN (SSPCON1<5>).
The SSPCON1 register allows control of the I
operation. Four mode selection bits (SSPCON1<3:0>)
allow one of the following I
• I
• I
• I
• I
• I
• I
Selection of any I
forces the SCL and SDA pins to be open-drain,
provided these pins are programmed as inputs by
setting the appropriate TRISC or TRISD bits. To ensure
proper operation of the module, pull-up resistors must
be provided externally to the SCL and SDA pins.
19.4.3
In Slave mode, the SCL and SDA pins must be
configured as inputs (TRISC<4:3> set). The MSSP
module will override the input state with the output data
when required (slave-transmitter).
The I
interrupt on an address match. Address masking will
allow the hardware to generate an interrupt for more
than one address (up to 31 in 7-bit addressing and up
to 63 in 10-bit addressing). Through the mode select
bits, the user can also choose to interrupt on Start and
Stop bits.
When an address is matched, or the data transfer after
an address match is received, the hardware auto-
matically will generate the Acknowledge (ACK) pulse
and load the SSPBUF register with the received value
currently in the SSPSR register.
Any combination of the following conditions will cause
the MSSP module not to give this ACK pulse:
• The Buffer Full bit, BF (SSPSTAT<0>), was set
• The overflow bit, SSPOV (SSPCON1<6>), was
In this case, the SSPSR register value is not loaded
into the SSPBUF, but bit SSPIF is set. The BF bit is
cleared by reading the SSPBUF register, while bit
SSPOV is cleared through software.
The SCL clock input must have a minimum high and
low for proper operation. The high and low times of the
I
MSSP module, are shown in timing parameter 100 and
parameter 101.
© 2006 Microchip Technology Inc.
2
C specification, as well as the requirement of the
Stop bit interrupts enabled
Stop bit interrupts enabled
Idle
before the transfer was received.
set before the transfer was received.
2
2
2
2
2
2
C Master mode, clock
C Slave mode (7-bit address)
C Slave mode (10-bit address)
C Slave mode (7-bit address) with Start and
C Slave mode (10-bit address) with Start and
C Firmware Controlled Master mode, slave is
2
C Slave mode hardware will always generate an
OPERATION
SLAVE MODE
2
C mode with the SSPEN bit set
2
C modes to be selected:
PIC18F2455/2550/4455/4550
Preliminary
2
C
19.4.3.1
Once the MSSP module has been enabled, it waits for
a Start condition to occur. Following the Start condition,
the 8 bits are shifted into the SSPSR register. All
incoming bits are sampled with the rising edge of the
clock (SCL) line. The value of register SSPSR<7:1> is
compared to the value of the SSPADD register. The
address is compared on the falling edge of the eighth
clock (SCL) pulse. If the addresses match and the BF
and SSPOV bits are clear, the following events occur:
1.
2.
3.
4.
In 10-Bit Address mode, two address bytes need to be
received by the slave. The five Most Significant bits
(MSbs) of the first address byte specify if this is a 10-bit
address. Bit R/W (SSPSTAT<2>) must specify a write so
the slave device will receive the second address byte.
For a 10-bit address, the first byte would equal ‘11110
A9 A8 0’, where ‘A9’ and ‘A8’ are the two MSbs of the
address. The sequence of events for 10-bit address is as
follows, with steps 7 through 9 for the slave-transmitter:
1.
2.
3.
4.
5.
6.
7.
8.
9.
The SSPSR register value is loaded into the
SSPBUF register.
The Buffer Full bit, BF, is set.
An ACK pulse is generated.
The MSSP Interrupt Flag bit, SSPIF, is set (and
interrupt is generated, if enabled) on the falling
edge of the ninth SCL pulse.
Receive first (high) byte of address (bits SSPIF,
BF and UA (SSPSTAT<1>) are set on address
match).
Update the SSPADD register with second (low)
byte of address (clears bit UA and releases the
SCL line).
Read the SSPBUF register (clears bit BF) and
clear flag bit SSPIF.
Receive second (low) byte of address (bits
SSPIF, BF and UA are set).
Update the SSPADD register with the first (high)
byte of address. If match releases SCL line, this
will clear bit UA.
Read the SSPBUF register (clears bit BF) and
clear flag bit SSPIF.
Receive Repeated Start condition.
Receive first (high) byte of address (bits SSPIF
and BF are set).
Read the SSPBUF register (clears bit BF) and
clear flag bit SSPIF.
Addressing
DS39632C-page 207