MEC1322 Datasheet, PDF (359/456 Pages) Microchip Technology – Keyboard and Embedded Controller for Notebook PC

MEC1322
The maximum speed at which the BC-Link Master Interface can operate reliably depends on the drive strength of the
BC-Link BCM_CLK and BCM_DAT pins, as well as the nature of the connection to the Companion device (over ribbon
cable or on a PC board). The following table shows the recommended maximum speeds over a PC board as well as a
12 inch ribbon cable for selected drive strengths. The frequency is set with the BC-Link Clock Select Register.
TABLE 31-2:
Pin Drive
Strength
16mA
BC-LINK MASTER PIN DRIVE STRENGTH VS. FREQUENCY
Max Freq
on PC Board
Min Value in
BC-Link Clock Select
Register
Max Freq
over Ribbon cable
24Mhz
1
16Mhz
Min Value in BC-Link
Clock Select Register
2
31.6 Host Interface
The registers defined for the BC-Link Master Interface are accessible by the various hosts as indicated in Section 31.11,
"EC-Only Registers".
31.7 Power, Clocks and Reset
31.7.1 POWER DOMAINS
TABLE 31-3:
POWER SOURCES
Name
VCC1
31.7.2 CLOCK INPUTS
Description
The logic and registers implemented in this block are powered by this
power well.
TABLE 31-4: CLOCK INPUTS
Name
48 MHz Ring Oscillator
31.7.3 RESETS
Description
This is the clock source for Keyboard Scan Interface logic.
TABLE 31-5: RESET SIGNALS
Name
VCC1_RESET
Description
This signal resets all the registers and logic in this block to their default
state.
31.8 Interrupts
This section defines the Interrupt Sources generated from this block.
TABLE 31-6: EC INTERRUPTS
Source
BCM_INT Busy
BCM_INT Err
BC_INT_N_WK
Description
Interrupt request to the Interrupt Aggregator, generated from the status
event BUSYdefined in the BC-Link Status Register.
Interrupt request to the Interrupt Aggregator, generated from the status
event defined in the BC-Link Status Register.
Wake-up request to the Interrupt Aggregator’s wake-up interface for BC-
Link Master port.
In order to enable BC-Link wakeup interrupts, the pin control registers for
the BC_INT# pin must be programmed to Input, Falling Edge Triggered,
non-inverted polarity detection.
 2014 - 2015 Microchip Technology Inc.
DS00001719D-page 359