Jon Williams' September column in Nuts & Volts Magazine features the Servo Player Module for the Propeller Platform, which we now have as a kit:

Jon designed the Servo Player to control servos in animatronics - it includes 2 analog joysticks, connections for 4 servos, configuration switches, audio sync output and even connections for using an external R/C transmitter in trainer mode.  It's a neat module - performers can use it to record and playback their performances and use the switches on the board to modify playback, change modes, or configure for whatever is most useful for them  Here's how to get started with the Servo Player Module;

Getting Started

Hardware

You'll need the Servo Player Module and a Propeller Platform.  If you're using the original Propeller Platform, you'll also need a Prop Plug.  You'll need a power supply,  6v output is best - and the higher the amperage, the better.  Finally, you'll need some servos - the Servo Player connects to servos with a universal J connector (Futaba, Hitec, and pretty much all commonly used servos), providing them with 5V power.  The Propeller Platform SD's voltage regulator provides 1.5A of current, enough for most standard servos.

The Servo Player connects to the Propeller as follows:

Full size PDF

P0 connects to the start / stop tactile switch, P16 & P17 connect to the bi-color LED.  The switches on P0..P6 are normally pulled down & they go to Vdd when the switch is activated.

Software

Be sure to download Jon's Nuts & Volts Column on the Servo Player here (pdf).  You'll also want the sample code, which you can download here.  To jump right in, unzip the code samples and open jm_joystick_servo_demo in the Propeller Tool.  This is a simple test program to make sure everything is working - it maps each axis on the joysticks to one of the servos.  Here's a little demo with an R/C car:

Several demos are included so you can see how the Servo Player works.  The included objects are great for use in your own projects, too.

Using An R/C Transmitter

You can connect an external R/C transmitter in trainer mode.  This mode sends your commands out via a 3 pin header (like a servo connector).  Connect the R/C transmitter cable to 3 pin headers marked 'P';

The Black wire of the connecter goes on the left-most pin.  Now, when you move the controls on your R/C transmitter, your inputs will also be sent to the Servo Player.  You'll also need code to read the input.  Start with the jm_vexin_servo_demo library, open it up in the Propeller Tool, connect the Propeller Platform and hit F10 to program the Prop.

Jumpers

There are 4 jumpers on the board for configuring the audio start output and the external R/C transmitter input.  If you aren't using either, then you don't need to worry about the jumpers.  If you are, here's how they work;

In the photo, the jumpers are parked - connecting them to just 1 pin is an easy way to store them.  If you need to use them, you'll jumper either the middle pin to the top pin, or the middle pin to the bottom pin.

• Jumper 1: Jumper to the bottom pin (marked 3) to provide 3.3V to the Audio Start connection.  Jumper to the top pin to provide 5V.
• Jumper 2: Also for Audio Start.  Jumper to 'OC' for open-collector logic output to Audio Start - when P23 on the Prop is high, it will drive the Audio Start signal line low.  Jumper to the '<' for regular signalling - when P23 is high, the Audio Start signal line is high.
• Jumper 3: Used for powering an external R/C transmitter.  Jumper to 5 to provide 5V power to the R/C transmitter.  Jumper to 3 to provide 3.3V power to the R/C transmitter.
• Jumper 4: Used to select a pullup or pulldown resistor on the external R/C transmitter signal line.  Jumper to G to select a pulldown resistor.  Jumper to 3 to select a pullup resistor.

Switches

There are 7 switches on the Servo Player Module, and they're connected to P0..P7;

When the switches are open, they Propeller's pins are pulled to ground with the resistor array.  When they're closed, they go to Vdd.

That's it!  We're excited about the Servo Player Module and we hope you get plenty of use out of it!

• Start Switch: P0
• DIP Switches: bottom-most switch (marked 1) is connected to P1, top-most switch (marked M2) is connected to P6.  Slide the switches to the left (away from the numbers marked on the DIP switch package) to close the switch.

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