Electronics

Miniboard

Fig. 1: Miniboard

At the beginning of the development of the Miniboard was one main point to design a board with dimensions fewer than 5 cm by 5 cm. Because one goal was to implement the board into Micro Sumo robots and these robots have a dimension of 5 cm by 5 cm by 5 cm. On the board the micro controller Xmega32A4 is used. Because this kind of micro controller is also used at the other elctronic platforms and so the students get to know the Xmega-Family. The board is designed to be the stand alone control unit in a small robot.

It can deal with:


Motor Control

The motor board has two full H-Bridges BD6232HFP from Rohm Semiconductor to control two DC motors. The BD6232HFP has the following features:

Part of the motor control is to manage the speed, the position and the odometric navigation system.


Digital Inputs/Outputs

The board supports up to 14 digital Input/Outputs. To these I/Os can be connected various sensors, e.g. infrared sensors to detect a black line in Line Following competition or to become aware of an obstacle or an opponent robot in Sumo competition. Also output interfaces, e.g. LCD interface can be connected.


Analog Inputs

To the board also can be connected up to four analogue input signals. The inputs have a voltage range from 0 V to 5 V and the ADC has a 10 bit resolution. They can be used for measuring the distance to an obstacle or an opponent robot. These inputs can also be used as digital input or output, if needed.


Power Supply

To stabilize the 5 V for the micro controller a LM7805 is used. This kind of voltage regulator can handle an input voltage up to 20 V. The drawback is, at a high difference between input and output voltage the power dissipation is also high. This is the reason why an additional board was developed. On this board is a step down converter witch can handle input voltages up to 42 V with a power factor from 90 % over the whole input voltage range from 8 V to 42 V. This board can be soldered instead the LM7805. Usually LiPo accumulators with 7.4 V or 11.1 V are used.