UR8HC007-001 Datasheet, PDF (6/18 Pages) Semtech Corporation – Input Device and Power Management Companion IC for Jupiter Devices

JUNO^TM FAMILY COMMUNICATIONS INTERFACE
The Juno™ family of controllers
implements two modes of serial
communications: The "Synchronous
Peripheral Interface" (SPI) mode
and the "Asynchronous Serial
Interface" (ASI).
The SPI is a synchronous bi-
directional, multi-slave interface that
supports bit rates up to 500 Kb/s.
Several Hosts and companion chips
implement the SPI protocol in order
to communicate with a wide range
of peripherals such as EEPROMs,
A/D converters, MCUs and other
system components. Alternatively,
the SPI may be implemented
through software on the Host side.
The diagrams below describe the SPI and ASI communications interfaces,
respectively.
SPI Communications Interface
Host
(master)
MOSI
MISO
SCLK
_SS
_ATN
_SS
USAR Juno™
(slave)
SLAVE 2
The Juno™ family implements the
_ATN as an additional hand-shake
signal in order to support low power
operation of the bus.
ASI Communications Interface
The ASI is an asynchronous
interface (UART type) that operates
at a fixed baud rate of 62.5 Kb/s.
Both interfaces are implemented
through the same set of four pins.
The IC determines the mode of
communication with the Host during
power-up by reading the value of
the SCLK/ISEL pin. If the pin is tied
low, the ASI mode is enabled. If it
is high, the SPI interface is enabled.
Host
CTS
RTS
RxD
TxD
UR8HC007
CTS
RTS
RxD
TxD
Please refer to the Juno^TM Technical
Reference Manual for a description
of handshake and critical timing
parameters for each interface.
ISEL
GND
Copyright ©1998-2001 Semtech Corporation
6
DOC8-007-001-DS-108
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