User manual

RP6 ROBOT SYSTEM - 2. The RP6 in detail
A few modules can use the interrupt lines for signalling the master microcontroller
either the arrival of new data, or whether a job has been completed and new com-
mands are being expected. Not providing these lines would force the master device to
repeatingly query some specific expansion modules for new data. Of course this meth-
od would be possible, but the alternative design with additional interrupt lines will
usually reduce bus traffic and CPU load. As the number of interrupt lines is restricted
to 3 signals and one free line reserved for user signals, you may have to assign one
line to several modules (e.g. all ultrasound sensors) and poll all modules subsequently
when an interrupt is signalled.
The other two expansion connectors labelled “USRBUS1” and “USRBUS2” on the main-
board are not interconnected. All lines are routed to soldering pads on all expansion
modules and you may apply your own signals to these pads.
“USRBUS” is an abbreviation of “User-Bus”. You may use this 14-pin expansion con-
nector for anything you want - your own bus system, additional power supply lines
(but be careful, the traces are rather thin and for low currents of max. 500mA only) or
anything else. Example given: you are able to interconnect two expansion modules
without providing connections to other modules. This might be useful for more com-
plex circuits or sensors, which cannot be placed on a single expansion module. This
method will tidy up your wiring.
Of course you can not add any number of expansion modules – 6 stacked modules at
the front- or backside will definitely overload your vehicle. Too many modules will also
cause problems by overloading the battery supply. As a general rule you may mount a
maximal number of 8 modules to the RP6: 4 at the front side and 4 at the backside.
The figure shows the connection diagram for both expan-
sion connectors. On the mainboard, pin 1 is always located
near the white label XBUS1 and XBUS2, respectively. Al-
ternatively, the pin is labelled with “1” at the connector-
position.
+UB is the battery-voltage, VDD is the +5V rail, GND la-
bels “Minus” or “Ground” (GND = Ground), MRESET labels
the Master Reset Signal, INTx are the Interrupt-lines, SCL
is the clock- and SDA the data-line of the I²C Bus.
Anything else you need has to be soldered to the USRBUS
connector pins.
Important note: Do not overload the supply lines VDD and +UB! These lines
can provide a maximum current of 1A each (this applies to both Pins TO-
GETHER! This means joined Pins 4+6 (+UB) and 3+5 (VDD) of the connect-
ors)!
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