Information

PIC18F2585/2680/4585/4680
DS80283E-page 4 © 2007 Microchip Technology Inc.
16. Module: MSSP
In its current implementation, the I
2
C™ Master
mode operates as follows:
1. The Baud Rate Generator for I
2
C in Master
mode is slower than the rates specified in
Table 17-3 of the Device Data Sheet.
For this revision of silicon, use the values
shown in Table 1 in place of those shown in
Table 17-3 of the Device Data Sheet. The
differences are shown in bold text.
2. Use the following formula in place of the one
shown in Register 17-4 (SSPCON1) of the
Device Data Sheet for bit description,
SSPM3:SSPM0 = 1000.
SSPADD = INT((F
CY/FSCL) – (FCY/1.111 MHz)) – 1
TABLE 1: I
2
C™ CLOCK RATE w/BRG
17. Module: MSSP
RCEN becomes set when the system is idle. In
normal operation, the setting of RCEN should be
ignored by the module while the system is not idle.
Work around
Wait for the system to become idle. This requires
a check for the following bits to be reset:
ACKEN, RCEN, PEN, RSEN and SEN.
Date Codes that pertain to this issue:
All engineering and production devices.
18. Module: MSSP
In an I
2
C system with multiple slave nodes, an
unaddressed slave may respond to bus activity
when data on the bus matches its address. The
first occurrence will set the BF bit. The second
occurrence will set the BF and the SSPOV bits. In
both situations, the SSPIF bit is not set and an
interrupt will not occur. The device will vector to the
Interrupt Service Routine only if the interrupt is
enabled and an address match occurs.
Work around
The I
2
C slave must clear the SSPOV bit after each
I
2
C event to maintain normal operation.
Date Codes that pertain to this issue:
All engineering and production devices.
F
OSC FCY FCY*2 BRG Value
F
SCL
(2 Rollovers of BRG)
40 MHz 10 MHz 20 MHz 0Eh 400 kHz
(1)
40 MHz 10 MHz 20 MHz 15h 312.5 kHz
40 MHz 10 MHz 20 MHz 59h 100 kHz
16 MHz 4 MHz 8 MHz 05h 400 kHz
(1)
16 MHz 4 MHz 8 MHz 08h 308 kHz
16 MHz 4 MHz 8 MHz 23h 100 kHz
4 MHz 1 MHz 2 MHz 01h 333 kHz
(1)
4 MHz 1 MHz 2 MHz 08h 100 kHz
4 MHz 1 MHz 2 MHz 00h 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.