FMT1000 Datasheet, PDF (7/29 Pages) Fairchild Semiconductor – Motion Tracking Module with Output of Orientation, Inertial Motion Data and Magnetic Field

1.7 Peripheral Interface Selection
The FMT1000-series modules are designed to be used
as a peripheral device in embedded systems. The
module supports Universal Asynchronous
Receiver/Transmitter (UART), inter-integrated circuit
(I²C) and the Serial Peripheral Interface (SPI) protocols.
The I²C and SPI protocols are well suited for
communications between integrated circuits with on-
board peripherals. The FMT1000-series modules have
four modes of peripheral interfacing. Only one mode can
be used at a time and is determined by the state of
peripheral selection pins PSEL0 and PSEL1 at startup.
Table 1 specifies how the PSEL lines select the
peripheral interface. Note that the module has internal
pull-ups. Not connecting PSEL results in a value of 1,
connecting PSEL to a GND results in a value of 0.
Examples for communication on embedded systems are
available at https://developer.mbed.org/teams/Fairchild-
Semiconductor
Table 1. Peripheral Interface Selection
Interface
I²C
SPI
UART Half-Duplex
UART Full-Duplex
PSEL0
1
0
1
0
PSEL1
1
1
0
0
1.7.1 Peripheral Interface Architecture
At its core the module uses the proprietary Xbus
protocol. This protocol is available on all interfaces,
UART (asynchronous serial port interfaces) and I²C and
SPI buses. The I²C and SPI buses differ from UART in
that they are synchronous and have a master-slave
relation in which the slave cannot send data by itself.
This makes the Xbus protocol not directly transferable to
these buses. For this the MTSSP protocol is introduced
that provides a way to exchange standard Xbus protocol
messages over the I²C and SPI buses.
Figure 5 shows how MTSSP is fitted in the module's
(simplified) communication architecture. The module
has generic Input- and Output-Queues for Xbus protocol
messages. For I²C and SPI these messages are
translated by the MTSSP layer. For the UART
connection these messages are transported as-is.
Figure 5. FMT Module Architecture
© 2015 Fairchild Semiconductor Corporation
FMT1000-series • Rev. 1.0
7
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