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UPD360

DS00002084C-page 38

 2016-2017 Microchip Technology Inc.

8.2.1

PIO SIMULTANEOUS UPDATE

A mechanism has been incorporated to enable multiple PIOs to be updated simultaneously. This is desirable to simplify

software and prevent devices controlled by the UPD360 from entering an intermediary unknown state. Of particular con-

cern would be devices responsible for managing power.

The Configure PIOx Registers (CFG_PIOx) CSR is updated by this function. When the simultaneous update request is

accepted by hardware, the contents of the PIO registers are simultaneously updated.

The example below illustrates simultaneous PIO update operation:

Software changes Configure PIOx Update Registers (CFG_PIOx_UPD) as required.

Software changes Configure PIO Output Update Register (CFG_PIO_OUT_UPD) as required.

Software sets the Configure PIOx Update Registers (CFG_PIOx_UPD) to initiate the update.

A pending PIO override blocks acceptance of the update request. Only after the pending PIO override function

is cleared will the device clear PIO_UPD_REQ. The pending PIO override is cleared via the PIO Override Enable

After the update is accepted, PIO_UPD_REQ clears automatically.

APPLICATION NOTE: If a PIO override is pending, the PIO simultaneous update is blocked.

8.2.2

PIO OVERRIDE

8.2.2.1

Overview

A mechanism is defined in this section to enable the state of a PIO to be changed without software intervention. This

provides a mechanism to instantaneously disable a power circuit, controlled by a UPD360 PIO, based upon a change

in the state of a selected PIO input, OCS detection or other event.

8.2.2.2

Description

Four override functions are included in device. For each function, a PIO or other source must be selected for monitoring

via the corresponding PIO Override x Source Select Registers (PIO_OVRx_SRC_SEL). The value to be monitored is

set in the PIO Override Monitor Value Register (PIO_OVR_MON_VAL) and is compared with the state of the respective

PIO. When these values match for an override, the enabled PIO outputs change their state accordingly.

PIO outputs controlled by an override are enabled by the PIO Override x Output Enable Registers (PIO_OVRx-

_OUT_EN). Each override has an instance in this register. A PIO may be used across multiple overrides.

Firmware can be notified that an override was executed via assertion of PIO_OVERRIDE_INT in the Interrupt Status

Note:

The Configure PIO Output Update Register (CFG_PIO_OUT_UPD) and Configure PIOx Update Registers

(CFG_PIOx_UPD) must be programmed consistently by software. If the output value bits are different

between the two registers, then the value in Configure PIOx Update Registers (CFG_PIOx_UPD) will be

used for updating the Configure PIOx Registers (CFG_PIOx) and the respective bit in Configure PIO Out-

put Register (CFG_PIO_OUT).

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