Datasheet

 2011 Microchip Technology Inc. DS39932D-page 313
PIC18F46J11 FAMILY
19.5.7.1 Baud Rate and Module
Interdependence
Because MSSP1 and MSSP2 are independent, they
can operate simultaneously in I
2
C Master mode at
different baud rates. This is done by using different
BRG reload values for each module.
Because this mode derives its basic clock source from
the system clock, any changes to the clock will affect
both modules in the same proportion. It may be
possible to change one or both baud rates back to a
previous value by changing the BRG reload value.
FIGURE 19-19: BAUD RATE GENERATOR BLOCK DIAGRAM
TABLE 19-3: I
2
C™ CLOCK RATE w/BRG
FOSC FCY FCY * 2 BRG Value
F
SCL
(2 Rollovers of BRG)
40 MHz 10 MHz 20 MHz 18h 400 kHz
(1)
40 MHz 10 MHz 20 MHz 1Fh 312.5 kHz
40 MHz 10 MHz 20 MHz 63h 100 kHz
16 MHz 4 MHz 8 MHz 09h 400 kHz
(1)
16 MHz 4 MHz 8 MHz 0Ch 308 kHz
16 MHz 4 MHz 8 MHz 27h 100 kHz
4 MHz 1 MHz 2 MHz 02h 333 kHz
(1)
4 MHz 1 MHz 2 MHz 09h 100 kHz
16 MHz 4 MHz 8 MHz 03h 1 MHz
(1)
Note 1: The I
2
C interface does not conform to the 400 kHz I
2
C specification (which applies to rates greater than
100 kHz) in all details, but may be used with care where higher rates are required by the application.
SSPM<3:0>
BRG Down Counter
CLKO
F
OSC/4
SSPxADD<6:0>
SSPM<3:0>
SCLx
Reload
Control
Reload