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HPID
R/W FIFOs
HPIA
Increment
HPIC
Access
type
UHPI_HD[15:0]
UHPI_HDS1, UHPI_HDS2
UHPI_HR/W
UHPI_HAS
UHPI_
HCNTL0
UHPI_
HCNTL1
UHPI_HINT
UHPI_HRDY
HPI
Host
Data
Address
or I/O
R/W
Data
strobes
IRQ
Ready
CPU
UHPI_HCS
Chip select
Processor
memory
HPI DMA
logic
Processor
UHPI_HHWIL
high
Logic
Introduction
956
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Host Port Interface (HPI)
21.1.3 Functional Block Diagram
is a high-level block diagram showing how the HPI connects a host (left side of figure) and the
processor internal memory (right side of figure). Host activity is asynchronous to the internal processor
clock that drives the HPI. The host functions as a master to the HPI. When HPI resources are temporarily
busy or unavailable, the HPI communicates this to the host by deasserting the HPI ready (UHPI_HRDY)
output signal.
The HPI supports multiplexed operation meaning the data bus is used for both address and data. Each
host cycle consists of two consecutive 16-bit transfers. When the host drives an address on the bus, the
address is stored in a 32-bit address register (HPIA) in the HPI, so that the bus can then be used for data.
The HPI contains two address registers (HPIAR and HPIAW), which can be used as separate address
registers for read accesses and write accesses (for details, see
A control register (HPIC) is accessible by the CPU and the host. The CPU uses HPIC to send an interrupt
request to the host, to clear an interrupt request from the host, and to monitor the HPI. The host uses
HPIC to configure and monitor the HPI, to send an interrupt request to the CPU, and to clear an interrupt
request from the CPU.
Data flow between the host and the HPI uses a temporary storage register, the 32-bit data register (HPID).
Data arriving from the host is held in HPID until the data can be stored elsewhere in the processor. Data
to be sent to the host is held in HPID until the HPI is ready to perform the transfer. When address
autoincrementing is used, read and write FIFOs are used to store burst data. If autoincrementing is not
used, the FIFO memory acts as a single register (only one location is used).
Figure 21-1. HPI Block Diagram