PIC18F2221-E/ML Microchip Technology, PIC18F2221-E/ML Datasheet - Page 208

• Manufacturer Part Number: PIC18F2221-E/ML
• Description: 4KB, Flash, 512bytes-RAM, 25I/O, 8-bit Family,nanoWatt 28 QFN 6x6mm TUBE
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F2221-E/ML

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, HLVD, POR, PWM, WDT
• Number Of I /o: 25
• Program Memory Size: 4KB (2K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 10x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 28-VQFN Exposed Pad, 28-HVQFN, 28-SQFN, 28-DHVQFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PIC18F2221/2321/4221/4321 FAMILY
18.4.17.2
During a Repeated Start condition, a bus collision
occurs if:
a)
b)
When the user deasserts SDA and the pin is allowed to
float high, the BRG is loaded with SSPADD<6:0> and
counts down to 0. The SCL pin is then deasserted and
when sampled high, the SDA pin is sampled.
FIGURE 18-31:
FIGURE 18-32:
DS39689F-page 208
A low level is sampled on SDA when SCL goes
from low level to high level.
SCL goes low before SDA is asserted low,
indicating that another master is attempting to
transmit a data ‘1’.
SDA
SCL
BCLIF
RSEN
S
SSPIF
SDA
SCL
RSEN
BCLIF
S
SSPIF
Bus Collision During a Repeated
Start Condition
BUS COLLISION DURING A REPEATED START CONDITION (CASE 1)
BUS COLLISION DURING REPEATED START CONDITION (CASE 2)
SCL goes low before SDA,
set BCLIF. Release SDA and SCL.
T
BRG
Sample SDA when SCL goes high.
If SDA = 0, set BCLIF and release SDA and SCL.
masters can assert SDA at exactly the same time.
If SDA is low, a bus collision has occurred (i.e., another
master is attempting to transmit a data ‘0’, Figure 18-31).
If SDA is sampled high, the BRG is reloaded and begins
counting. If SDA goes from high-to-low before the BRG
times out, no bus collision occurs because no two
If SCL goes from high-to-low before the BRG times out
and SDA has not already been asserted, a bus collision
occurs. In this case, another master is attempting to
transmit a data ‘1’ during the Repeated Start condition,
see Figure 18-32.
If, at the end of the BRG time-out, both SCL and SDA
are still high, the SDA pin is driven low and the BRG is
reloaded and begins counting. At the end of the count,
regardless of the status of the SCL pin, the SCL pin is
driven low and the Repeated Start condition is
complete.
T
Cleared in software
BRG
© 2009 Microchip Technology Inc.
Interrupt cleared
in software
‘0’
‘0’
‘0’