PIC24HJ128GP206-I Datasheet, PDF (158/286 Pages) Microchip Technology – High-Performance, 16-Bit Microcontrollers

PIC24HJXXXGPX06/X08/X10
16.11 Slope Control
The I²C standard requires slope control on the SDAx
and SCLx signals for Fast mode (400 kHz). The control
bit, DISSLW, enables the user to disable slew rate con-
trol if desired. It is necessary to disable the slew rate
control for 1 MHz mode.
16.12 Clock Arbitration
Clock arbitration occurs when the master deasserts the
SCLx pin (SCLx allowed to float high) during any
receive, transmit or Restart/Stop condition. When the
SCLx pin is allowed to float high, the Baud Rate Gen-
erator (BRG) is suspended from counting until the
SCLx pin is actually sampled high. When the SCLx pin
is sampled high, the Baud Rate Generator is reloaded
with the contents of I2CxBRG and begins counting.
This ensures that the SCLx high time will always be at
least one BRG rollover count in the event that the clock
is held low by an external device.
16.13 Multi-Master Communication, Bus
Collision and Bus Arbitration
Multi-Master mode support is achieved by bus
arbitration. When the master outputs address/data bits
onto the SDAx pin, arbitration takes place when the
master outputs a ‘1’ on SDAx by letting SDAx float high
while another master asserts a ‘0’. When the SCLx pin
floats high, data should be stable. If the expected data
on SDAx is a ‘1’ and the data sampled on the
SDAx pin = 0, then a bus collision has taken place. The
master will set the I²C master events interrupt flag and
reset the master portion of the I²C port to its Idle state.
DS70175F-page 156
© 2007 Microchip Technology Inc.