PIC18F4520-I/P Microchip Technology Inc., PIC18F4520-I/P Datasheet - Page 197

• Manufacturer Part Number: PIC18F4520-I/P
• Description: 40 Pin, 32 KB Flash, 1536 RAM, 36 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F4520-I/P

• A/d Inputs: 13-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 10 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 36
• Interface: I2C/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 40-pin PDIP
• Programmable Memory: 32K Bytes
• Ram Size: 1.5K Bytes
• Speed: 40 MHz
• Timers: 1-8-bit, 3-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

17.4.14
While in Sleep mode, the I
addresses or data and when an address match or com-
plete byte transfer occurs, wake the processor from
Sleep (if the MSSP interrupt is enabled).
17.4.15
A Reset disables the MSSP module and terminates the
current transfer.
17.4.16
In Multi-Master mode, the interrupt generation on the
detection of the Start and Stop conditions allows the
determination of when the bus is free. The Stop (P) and
Start (S) bits are cleared from a Reset or when the
MSSP module is disabled. Control of the I
be taken when the P bit (SSPSTAT<4>) is set, or the
bus is Idle, with both the S and P bits clear. When the
bus is busy, enabling the SSP interrupt will generate
the interrupt when the Stop condition occurs.
In multi-master operation, the SDA line must be
monitored for arbitration to see if the signal level is the
expected output level. This check is performed in
hardware with the result placed in the BCLIF bit.
The states where arbitration can be lost are:
• Address Transfer
• Data Transfer
• A Start Condition
• A Repeated Start Condition
• An Acknowledge Condition
FIGURE 17-25:
 2004 Microchip Technology Inc.
SDA
SCL
BCLIF
SLEEP OPERATION
EFFECTS OF A RESET
MULTI-MASTER MODE
BUS COLLISION TIMING FOR TRANSMIT AND ACKNOWLEDGE
2
C module can receive
Data changes
while SCL = 0
2
C bus may
PIC18F2420/2520/4420/4520
Preliminary
SDA released
by master
SDA line pulled low
by another source
17.4.17
Multi-Master mode support is achieved by bus arbitra-
tion. When the master outputs address/data bits onto
the SDA pin, arbitration takes place when the master
outputs a ‘1’ on SDA, by letting SDA float high and
another master asserts a ‘0’. When the SCL pin floats
high, data should be stable. If the expected data on
SDA is a ‘1’ and the data sampled on the SDA pin = 0,
then a bus collision has taken place. The master will set
the Bus Collision Interrupt Flag, BCLIF and reset the
I
If a transmit was in progress when the bus collision
occurred, the transmission is halted, the BF flag is
cleared, the SDA and SCL lines are deasserted and the
SSPBUF can be written to. When the user services the
bus collision Interrupt Service Routine and if the I
bus is free, the user can resume communication by
asserting a Start condition.
If a Start, Repeated Start, Stop or Acknowledge condi-
tion was in progress when the bus collision occurred, the
condition is aborted, the SDA and SCL lines are deas-
serted and the respective control bits in the SSPCON2
register are cleared. When the user services the bus col-
lision Interrupt Service Routine and if the I
the user can resume communication by asserting a Start
condition.
The master will continue to monitor the SDA and SCL
pins. If a Stop condition occurs, the SSPIF bit will be set.
A write to the SSPBUF will start the transmission of
data at the first data bit, regardless of where the
transmitter left off when the bus collision occurred.
In Multi-Master mode, the interrupt generation on the
detection of Start and Stop conditions allows the deter-
mination of when the bus is free. Control of the I
can be taken when the P bit is set in the SSPSTAT
register, or the bus is Idle and the S and P bits are
cleared.
2
C port to its Idle state (Figure 17-25).
MULTI -MASTER COMMUNICATION,
BUS COLLISION AND BUS
ARBITRATION
Sample SDA. While SCL is high,
data doesn’t match what is driven
by the master.
Bus collision has occurred.
Set bus collision
interrupt (BCLIF)
DS39631A-page 195
2
C bus is free,
2
C bus
2
C