![Texas Instruments AM1808 Скачать руководство пользователя страница 977](http://html.mh-extra.com/html/texas-instruments/am1808/am1808_technical-reference-manual_1094558977.webp)
HINT bit=0
HINT signal
is high
is low
HINT signal
HINT bit=1
CPU writes 1
to HINT bit
Host writes 1
to HINT bit
Interrupt
active
CPU writes 0
to HINT bit
No interrupt/
interrupt
cleared
Host writes 0 or 1
to HINT bit
CPU writes 0 or 1
to HINT bit
Host writes 0
to HINT bit
Architecture
977
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Host Port Interface (HPI)
21.2.9.2 HINT Bit: CPU-to-Host Interrupts
The HINT bit in HPIC allows the CPU to send an interrupt request to the host. The use of the HINT bit is
summarized in
Figure 21-16. CPU-to-Host Interrupt State Diagram
If the CPU writes 1 to the HINT bit of HPIC, the HPI drives the UHPI_HINT signal low, indicating an
interrupt condition to the host. Before the CPU can use the HINT bit generate a subsequent interrupt to
host, the host must acknowledge the current interrupt by writing 1 to the HINT bit. When the host does
this, the HPI clears the HINT bit (HINT = 0), and this drives the UHPI_HINT signal high. The CPU should
read HPIC and make sure HINT = 0 before generating subsequent interrupts.
Writes of 0 have no effect. A hardware reset immediately clears the HINT bit and thus clears an active
CPU-to-host interrupt.
21.2.10 EDMA Event Support
The HPI does not provide synchronization events to the EDMA system. Memory accesses from the HPI
are handled automatically, independent of the EDMA controller. The HPI controller has its own dedicated
DMA and its operation and configuration are transparent.
21.2.11 Power Management
The HPI peripheral can be placed in reduced-power modes to conserve power during periods of low
activity. The power management of the HPI peripheral is controlled by the processor Power and Sleep
Controller (PSC). The PSC acts as a master controller for power management for all of the peripherals on
the device. For detailed information on power management procedures using the PSC, see the
Power and
Sleep Controller (PSC)
chapter.