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December 2012

Raspberry Pi Setup

Wednesday, 12 December 2012 Category : Comms, Implementation, Phase Two 0

The offboard system uses the raspberry pi as the base station to send and receive signals from the iPads over the network interface and process the messages and send control packets to the game master Xbee.

This Xbee is connected to the raspberry pi using a slice of pi interface board which sends and receives serial signals from the serial GPIO TX and RX pins on the raspberry pi to the UART data in and UART data out pins on the Xbee.

Laser Detection: Handling Multiple Detector Circuits

Category : Detection, Implementation, Laser, Phase Two 0

In the post Laser Detection it was discussed how to set up a detector circuit and how the Arduino would recognise when the LaserBot was hit through the use of an interrupt. That was only for one detector circuit. However, three detector circuits are wanted on the LaserBot to make the game more interesting – more targets to shoot at, different points for the different targets etc.

PROBLEM ENCOUNTERED WITH ONE INTERRUPT

At first, only one interrupt was going to be used for all three detector circuits. This caused a problem in detecting which target had been hit as the interrupt only notifies the Arduino that it has been hit but not which target has been hit. The idea was then to have an output coming off each circuit which would then have its own individual port on the Arduino. When the interrupt said that the Arduino had been hit, the Arduino could then check the three different ports and see which ports state had changed. This, however, did not work as the interrupt joined all three circuits together, causing all three circuits to change state when they were hit.

Therefore, it was decided to use the two interrupts available on the Arduino. Two detector circuits would be connected to one interrupt, and the other circuit would be connected to the other interrupt. This meant that the Arduino could differentiate between two circuits, but not three. So, the user could get two different scores for hitting targets, rather than three different scores, which is not a big loss in terms of flexibility for the game.

Platform Construction

Monday, 10 December 2012 Category : Implementation, Phase Two 0

The Tamiya tank systems, gearbox, tracks and platforms all came with instructions and although they had many small parts and were time consuming to assemble were otherwise relatively straightforward to assemble and test.