PIC16F872-E/SP Microchip Technology, PIC16F872-E/SP Datasheet - Page 660

• Manufacturer Part Number: PIC16F872-E/SP
• Description: IC,MICROCONTROLLER,8-BIT,PIC CPU,CMOS,DIP,28PIN,PLASTIC
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F872-E/SP

• Rohs Compliant: YES
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 22
• Program Memory Size: 3.5KB (2K x 14)
• Program Memory Type: FLASH
• Eeprom Size: 64 x 8
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 5x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 28-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PICmicro MID-RANGE MCU FAMILY
A.4
A.4.1
DS31034A-page 34-8
Multi-master
Arbitration
The I
When two or more masters try to transfer data at the same time, arbitration and synchronization
occur.
Arbitration takes place on the SDA line, while the SCL line is high. The master which transmits a
high when the other master transmits a low loses arbitration
output stage. A master which lost arbitration can generate clock pulses until the end of the data
byte where it lost arbitration. When the master devices are addressing the same device, arbitra-
tion continues into the data.
Figure A-9:
Masters that also incorporate the slave function, and have lost arbitration must immediately
switch over to slave-receiver mode. This is because the winning master-transmitter may be
addressing it.
Arbitration is not allowed between:
• A repeated START condition
• A STOP condition and a data bit
• A repeated START condition and a STOP condition
Care needs to be taken to ensure that these conditions do not occur.
2
C protocol allows a system to have more than one master. This is called multi-master.
Multi-Master Arbitration (Two Masters)
DATA 2
SDA
SCL
DATA 1
transmitter 1 loses arbitration
DATA 1 SDA
(Figure
1997 Microchip Technology Inc.
A-9), and turns off its data