MEC1404 Datasheet, PDF (320/572 Pages) Microchip Technology – Keyboard and Embedded Controller Products for Notebook PC

MEC140X/1X
22.3.1 POWER DOMAINS
VTR
22.3.2
Name
CLOCK INPUTS
Description
The registers and logic in this block are powered by VTR.
Name
48 MHz Ring Oscillator
22.3.3 RESETS
Description
The 48 MHz Ring Oscillator is used for synchronizing the GPIO inputs.
Name
Description
nSYSRST
nSIO_RESET
This reset is asserted when VTR is applied.
This is an alternate reset condition, typically asserted when the main
power rail is asserted. This reset is used for VCC Power Well Emulation.
22.4 Interrupts
This section defines the Interrupt Sources generated from this block.
Source
Description
GPIO_Event
Each pin in the GPIO Interface has the ability to generate an interrupt
event. This event may be used as a wake event.
The GPIO Interface can generate an interrupt source event on a high
level, low level, rising edge and falling edge, as configured by the
Interrupt Detection (int_det) bits in the Pin Control Register associated
with the GPIO signal function.
Note: The minimum pulse width required to generate an inter-
rupt/wakeup event is 5ns.
22.5 Description
The GPIO Interface refers to all the GPIOxxx pins implemented in the design. GPIO stands for General Purpose I/O.
The GPIO signals may be used by firmware to both monitor and control a pin in “bit-banged” mode. The GPIOs may be
individually controlled via their Pin Control Register or group controlled via the Output and Input GPIO registers. The
GPIO Output Control Select
The GPIO Pin control registers are used to select the alternate functions on GPIO pins (unless otherwise specified), to
control the buffer direction, strength, and polarity, to control the internal pull-ups and pull-downs, for VCC emulation, and
for selecting the event type that causes a GPIO interrupt.
The GPIO input is always live, even when an alternate function is selected. Firmware may read the GPIO input anytime
to see the value on the pin. In addition, the GPIO interrupt is always functional, and may be used for either the GPIO
itself or to support the alternate functions on the pin. See FIGURE 22-1: GPIO Interface Block Diagram on page 319.
22.5.1 ACCESSING GPIOS
There are two ways to access GPIO output data. Bit [10] is used to determine which GPIO output data bit affects the
GPIO output pin.
DS00001956D-page 320
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