User Manual

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Connecting to Arduino and other TTL Serial Microcomputers
Advanced Digital Motor Controller User Manual 179
FIGURE 14-4. Simplified TTL to RS232 connection
The data sent from the TTL serial port are 0-3V and can be directly connected to the con-
troller’s RS232 input where it will be captured as valid 0-1 levels.
The data at the output of the controller is +/-10V. At the other end of the resistor, the
voltage is clamped to around 0-3.3V by the protection diodes that are included in the Ar-
duino MCU. However, to avoid any stress it is highly recommended to insert the 2 diodes
shown on the diagram.
To operate, the RS232 output must be set to inverted. This must be done from the Con-
sole of the Roborun Utility while connected via USB. This will only work on newer control-
ler models fitted with firmware version 1.6a or more recent.
From the Console, send the following commands:
^RSBR nn
where nn =
5: 115200 + Inverted RS232
6: 57600 + Inverted RS232
7: 38400 + Inverted RS232
8: 19200 + Inverted RS232
9: 9600 + Inverted RS232
Make sure that the controller respond to this command with a +. Check that the value has
been accepted by sending ~RSBR. If a - is replied or if the value is different than the one
entered, then the hardware and/or firmware does not support serial inverted and cannot
be used with this circuit.
Send %EESAV from the console to store the new configuration to flash.