MEC1322 Datasheet, PDF (219/456 Pages) Microchip Technology – Keyboard and Embedded Controller for Notebook PC

MEC1322
16.6 Power, Clocks and Reset
This section defines the Power, Clock, and Reset parameters of the block.
16.6.1 POWER DOMAINS
TABLE 16-1:
POWER SOURCES
Name
VCC1
16.6.2 CLOCK INPUTS
Description
The logic and registers implemented in this block reside on this single
power well.
TABLE 16-2: CLOCK INPUTS
Name
32KHz_Clk
16.6.3 RESETS
Description
The 32KHz_Clk clock input is the clock source to the Watchdog Timer
functional logic, including the counter.
TABLE 16-3: RESET SIGNALS
Name
VCC1_RESET
Description
Power on Reset to the block. This signal resets all the register and logic
in this block to its default state.
TABLE 16-4: RESET OUTPUT EVENT
Source
Description
WDT Event
Pulse generated when WDT expires. This signal is used to reset the
embedded controller and its subsystem.
The event is cleared after an VCC1_RESET.
16.7 Description
16.7.1 WDT OPERATION
16.7.1.1 WDT Activation Mechanism
The WDT is activated by the following sequence of operations during normal operation:
1. Load the WDT Load Register with the count value.
2. Set the WDT Enable bit in the WDT Control Register.
The WDT Activation Mechanism starts the WDT decrementing counter.
16.7.1.2 WDT Deactivation Mechanism
The WDT is deactivated by the clearing the WDT Enable bit in the WDT Control Register. The WDT Deactivation Mech-
anism places the WDT in a low power state in which clock are gated and the counter stops decrementing.
16.7.1.3 WDT Reload Mechanism
The WDT must be reloaded within periods that are shorter than the programmed watchdog interval; otherwise, the WDT
will underflow and a WDT Event will be generated and the WDT Status bit will be set in the WDT Control Register. It is
the responsibility of the user program to continually execute code which reloads the watchdog timer, causing the counter
to be reloaded
There are three methods of reloading the WDT: a write to the WDT Load Register, a write to the WDT Kick Register, or
WDT event.
 2014 - 2015 Microchip Technology Inc.
DS00001719D-page 219