Intel
®
81341 and 81342—I
2
C Bus Interface Units
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
932
Order Number: 315037-002US
16.6
Glitch Suppression Logic
The I
2
C Bus Interface Unit has built-in glitch suppression logic. Glitches are suppressed
according to: 2 * I
2
C clock period. For example, with the 33 MHz (30. ns period) I
2
C
clock glitches of 60ns or less are suppressed. This is within the 50 ns glitch suppression
specified.
16.7
Reset Conditions
The I
2
C unit is reset with internal bus reset. Software is responsible for ensuring the
I
2
C unit is not busy (ISR[3]) before asserting reset. Software is also responsible for
ensuring the I
2
C bus is idle when the unit is enabled after reset. When directed to
reset, the I
2
C unit returns to its default reset condition with the exception of the ISAR.
ISAR is not affected by a reset.
When the Unit Reset bit in the ICRx is set, only the 81341 and 81342 I
2
C unit resets,
the associated I
2
C MMRs remain intact. When resetting the I
2
C unit with the ICRx unit
reset, use the following guidelines:
1. In the ICRx register, set the reset bit and clear the remainder of the register.
2. Clear the ISRx register.
3. Clear reset in the ICRx.
16.8
Register Definitions
The following registers are associated with the I
2
C Bus Interface Units. Each I
2
C Bus
Interface Unit has five memory-mapped control registers for independent operation. In
register titles, x is 0 or 1 for unit 0 or 1, respectively.
They are all located within the peripheral memory- mapped address space of the 81341
and 81342.
Table 587. I
2
C Register Summary
Section, Register Name, Acronym, Page
Section 16.8.1, “I2C Control Register x — ICRx” on page 933
Section 16.8.2, “I2C Status Register x — ISRx” on page 935
Section 16.8.3, “I2C Slave Address Register x — ISARx” on page 937
Section 16.8.4, “I2C Data Buffer Register x — IDBRx” on page 938
Section 16.8.5, “I2C Bus Monitor Register x — IBMRx” on page 939
Section 16.8.6, “I2C Manual Bus Control Register x — IMBCRx” on page 940