Internal Communication Interfaces
The Ethernet switch:
A 10/100 Ethernet 5 port switch interconnects the
different high level peripherals of the robot
forming an embedded LAN. From those 5 ports,
one is not available and another is necessarily
taken by the Access Cube. From the 3 left, one
port is generally taken by the IP camera but can
be made available depending of the application.
This leaves normally two available ports where
we can add other peripherals if needed. For those
to be reachable from outside the robot, this one
will have to be reconfigured (see pag 15).
The I²C bus:
The I²C bus interconnects the micro-controllers in
charge of the low level modules to the central
processor that acts as a bridge with the upper
levels of the robot architecture. The central
processor works always as the master and all
communications necessarily pass by it. Up to 127
devices can be connected. The I²C is accessible on
pin 5 (GND), 6(SCL) and 9(SDA) of the DSUB-9
connector located on the RIGHT of the robot. The
program ../root/i2cdetect that can be found in the
CPU allows to detect the devices connected to the
bus. The address of the chip in charge of the left
wheels (0xA2) can be seen as 0x51, the one of the
right wheels (0xA4) as 0x52 and the ADC can be
seen as 0x9C.
The RS232 ports:
One RS232 port (RX,TX and GND) is available on the DSUB-9 connector of the left. This port
presents a TTL signal, for peripherals using standard PC signals, an interface such as the
MAX232 is needed.
8
This diagram shows the signal pinout
of the DSUB-9 connectors.The
RS232 signals are found on the
connector located on the left while
the I²C signals can be found on the
connector located on the right of the
robot.
