PIC18F452-I/L Microchip Technology Inc., PIC18F452-I/L Datasheet - Page 161

• Manufacturer Part Number: PIC18F452-I/L
• Description: 44 PIN, 32 KB FLASH, 1536 RAM, 34 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F452-I/L

• A/d Inputs: 8-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: 44-pin PLCC
• 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

15.4.14
While in SLEEP mode, the I
addresses or data, and when an address match or
complete byte transfer occurs, wake the processor
from SLEEP (if the MSSP interrupt is enabled).
15.4.15
A RESET disables the MSSP module and terminates
the current transfer.
15.4.16
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
may 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 moni-
tored 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 15-25:
© 2006 Microchip Technology Inc.
SDA
SCL
BCLIF
SLEEP OPERATION
EFFECT OF A RESET
MULTI-MASTER MODE
BUS COLLISION TIMING FOR TRANSMIT AND ACKNOWLEDGE
Data changes
while SCL = 0
2
C module can receive
2
C bus
SDA released
by master
SDA line pulled low
by another source
15.4.17
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
port to its IDLE state (Figure 15-25).
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 de-asserted, and
the SSPBUF can be written to. When the user services
the bus collision Interrupt Service Routine, and if the
I
asserting a START condition.
If a START, Repeated START, STOP, or Acknowledge
condition was in progress when the bus collision
occurred, the condition is aborted, the SDA and SCL
lines are de-asserted, and the respective control bits in
the SSPCON2 register are cleared. When the user ser-
vices the bus collision Interrupt Service Routine, and if
the I
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
determination of when the bus is free. Control of the I
bus 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 bus is free, the user can resume communication by
2
C bus is free, the user can resume communication
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)
PIC18FXX2
DS39564C-page 159
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2
C
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