Bluetooth Remote Control （2）

Published:2011/8/3 21:02:00 Author:Phyllis From:SeekIC

By Richard Hoptroff

Modified BoE

The circuit diagram of the modified BoE (Board of Education) is shown in Figure 1. The ’brains’ are a BS2p (BASIC Stamp 2) module which is plugged into the 24-way socket. Like its 1999 predecessor, this BoE has an RS232 connector (K2) and a prototyping area enclosed between K7, K3, K6, K8, K4 and K5. We’ll use the area later to fit a couple of components the robot needs to be able to tell you its whereabouts. The Flexipanel Bluetooth module is plugged straight onto a dedicated socket, K9.




The BoE has its own voltage regulator, IC2, and when used on its own (for example, during programming sessions) can be powered from a 9-volt battery. The programming utilities and the BASIC editor are available from Parallax Inc.. Just look for Board of Education on their website
www.parallax.com and you’ll find a mass of (free) information.

The component mounting plan of the new BoE is given in Figure 2. Hoorays and applause at this point because the board is single-sided.




Tracking robot

If your friends sniff at yet another buggy-style little robot, tell them that this remote controller differs from many others in being able to send information back to the handheld device using data over a radio link. By using an electronic compass mounted on the robot, a route trace is recorded and reported back to the handheld unit.

Figure 3 shows what to add to the BoE to make it suitable for our experiment. First, there is the combined FlexiPanel-Bluetooth module hooked up to the BS2p by five lines. The two units employ bidirectional serial communication with handshaking. As you will have surmised, the FlexiPanel is also a microcontroller system (and an intelligent one, too)! The BS2p runs software capable of sending commands that request or modify FlexiPanel values, content or status information. Moreover, FlexiPanel can request BS2p attention when a client device has changed a control via Bluetooth. This is done using a kind of interrupt conveyed via the Data line which in our case is monitored by an LED.




The electronic compass module type CMPS03 is an I2C device from Devan-tec. It is available from, among others, Milford Instruments.

The BoE with its extension circuitry crammed in the prototyping area is mounted on the BoE-Bot robot superstructure available from Parallax Inc. This has motorized wheels which may be controlled by pulse width modulation direct from the BASIC Stamp as indicated in Figure 3. The tracking robot. ready to start on its journey, is shown in the introductory photograph. Note that the photo shows the Parallax BoE.

FlexiPanel and BS2p programming

Using FlexiPanel Designer, a programming utility supplied by Hoptroff, a user interface is created containing:
-compass bearing display;
-latching pushbuttons for stop, forward, reverse, left and right;
-a table showing the route traced by the robot.

Flexipanel Designer generates a program for PBasic that allows the FlexiPanel hardware to be programmed. Using the PC and Basic Stamp Editor, this piece of software is downloaded onto the Stamp where it is executed. It may happen that FlexiPanel has to be reset first, for example, when an earlier attempt at programming went wrong. In that case, the circuit supply voltage has to be switched off and on again — the reset button on the BoE having an effect on the Stamp only and not on the FlexiPanel! When the circuit is switched on, the programming will recommence automatically

the program still being available in EEPROM, it does not have to be loaded again from the PC. It should be noted that FlexiPanel needs about 10 seconds to boot so you can stir your tea or coffee before programming actually commences. To have at least an indication of what’s happening during the boot-up phase, a low-current LED may be connected between the Data line and ground, not forgetting a 1-k resistor — see Figure 3. After switching on the supply or after a soft reset of the module (which happens automatically after programming), the LED will light up for a few seconds and then go out once booting is finished. The LED will also light briefly when FlexiPanel receives a command over Bluetooth (interrupt request).

The result of the using FlexiPanel Designer may be seen in the What do I with it inset: simple buttons to press on a pocket PC or GSM phone, and a map returned by the robot telling you where it went!




When the user interface has been programmed into the FlexiPanel module, the BASIC Stamp is loaded with the runtime program shown in Listing 1.

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