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Architecture
958
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Host Port Interface (HPI)
21.2 Architecture
21.2.1 Clock Control
For detailed information on the PLLs and clock distribution on the processor, see the
Phase-Locked Loop
Controller (PLLC)
chapter.
21.2.2 Memory Map
The HPI can be used by the host to access on-chip device memory, peripheral, and memory-mapped
registers. See your device-specific data manual for more detailed information.
21.2.3 Signal Descriptions
shows the a description of the HPI signals.
Table 21-1. HPI Pins
Pin
Type
Host Connection
Function
UHPI_HCNTL[1:0]
I
Address or control pins
HPI access control inputs
. The HPI latches the logic levels of these
pins on the falling edge of internal HSTRB (for details about internal
HSTRB, see
). The four binary states of these pins
determine the access type of the current transfer (HPIC, HPIA, HPID
with and without autoincrementing).
UHPI_HCS
I
Chip select pin
HPI chip select
. UHPI_HCS must be low for the HPI to be selected by
the host. UHPI_HCS can be kept low between accesses. UHPI_HCS
normally precedes an active UHPI_HDS (data strobe) signal, but can be
connected to a UHPI_HDS pin for simultaneous select and strobe
activity.
UHPI_HR/W
I
R/W strobe pin
HPI read/write
. On the falling edge of internal HSTRB, UHPI_HR/W
indicates whether the current access is to be a read or write operation.
Driving UHPI_HR/W high indicates the transfer is a read from the HPI,
while driving UHPI_HR/W low indicates a write to the HPI.
UHPI_HHWIL
I
Address or control pins
Halfword identification line
. The host uses UHPI_HHWIL to identify
the first and second halfwords of the host cycle. UHPI_HHWIL must be
driven low for the first halfword and high for the second halfword.
UHPI_HAS
I
None
Address strobe
. Connect to logic high.
UHPI_HINT
O/Z
Interrupt pin
Host Interrupt
. The CPU can interrupt the host processor by writing a 1
to the HINT bit of HPIC. Before subsequent UHPI_HINT interrupts can
occur, the host must acknowledge interrupts by writing a 1 to the HINT
bit. This pin is active-low (that is, when an interrupt is asserted from the
host, the state of this signal is low) and inverted from the HINT bit value
in HPIC.
UHPI_HDS1 and
UHPI_HDS2
I
Read strobe and write
strobe pins or any data
strobe pin
HPI data strobe pins
. These pins are used for strobing data in and out
of the HPI (for data strobing details, see
). The direction
of the data transfer depends on the logic level of the UHPI_HR/W
signal. The UHPI_HDS signals are also used to latch control
information on the falling edge. During an HPID write access, data is
latched into the HPID register on the rising edge of UHPI_HDS. During
read operations, these pins act as output-enable pins of the host data
bus.
UHPI_HD[15:0]
I/O/Z
Data bus
HPI data bus
. The HPI data bus carries the address and data to/from
the HPI.
UHPI_HRDY
O/Z
Asynchronous ready pin
HPI-ready signal
. When the HPI drives UHPI_HRDY low, the host has
permission to complete the current host cycle. When the HPI drives
UHPI_HRDY high, the HPI is not ready for the current host cycle to
complete.