Category: Kit

Serial Arduino and CC2500

Recently I built a one-off serial Arduino with a CC2500 for someone wanting to control a couple of LivingColors and through an external system.

This is what Patrice has built with it. It seems like a big setup (compared to most Arduino projects) and I’m pleased it works.

Control Living Colors by Beckhoff SPS

Nice setup !

The serial Arduino is useful if you want to control LivingColors lamps from a system without USB.

Using the CC2500 Arduino Shield

Software : the Arduino Library

( the hardware is described here )

Update #2 : the LivingColors library has been updated, the transmit power is higher and the range should be longer.

Update : the example program and library has been updated to Arduino version 1.0. New version of the example program is here : a_LiCo_Control_A1.zip , the LivingColors library is here : LivingColors.zip

The software consist of a library for the Arduino that can control a Philips LivingColors and a couple of sample programs. The library takes care of sending an receiving of messages using the CC2500 and can be used as a basis to communicate between two shields.

The library can be found here for Arduino version 1.0 (and here for older versions) and should be saved in the  “libraries” directory of the Arduino environment (this is the “hardware/libraries” directory in older versions of Arduino). You should have a  “<arduino>\libraries\LivingColors” directory with the files :

  • CC2500.cpp
  • CC2500.h
  • ColourConversion.cpp
  • ColourConversion.h
  • keywords.txt
  • LivingColors.cpp
  • LivingColors.h

The library can be found here for Arduino version 1.0 (and here for older versions) and the files are well documented.

The source code has a GPL license.  The code is based on code by Jeroen Domburg, known from various hacks on Hack a day and Tweakers, and described in an article van of the dutch edition of Elektor in May 2008. George Mathijssen cleaned up the code and got it working as an Arduino library.

The library is likely to have bugs and omissions. The RGB to HSI conversion seems a bit wrong and we ignore the ACK and NACK responses from the LivingColors lamp. Fixes and improvements are welcome !

LiCo_Control : an example of an Arduino application.

To test the library i have made an application to control LivingColors lamps. The application receives commands by serial over USB, you can control it with something like Putty or HyperTerminal.

When LiCo is ready to execute a command it sends a “!”. If it did not understand a command it sends a “?”.

The available command’s are :

Command Function
r reset
wn-rrr-ggg-bbb r, g and b are numbers 000 to 255. Example “w000-255-000\” for bright green. n is the lamp number.
hn-hhh-sss-iii h, s and i are numbers 000 to 255. No example for now. n is the lamp number.
i print info
nn turn lamp number n on
fn turn lamp number noff
ee e = 0 echo off, e = 1 echo on.
l listen for addresses. Use i to list addresses.
saabbccddeeffgghhii store address in a..i. 9 numbers as 2 digit hex
? dummy command.

Using the application to control a LivingColors lamp :

In LiCo-Control you can get control over the lamp by  :

  • Switching the lamp on with the remote.
  • Opening a connection to the Arduino board with a terminal application (putty, hyperterminal.. etc.).
  • Telling the application to learn the code of the lamp by sending the “l” command..
  • .. and control the lamp with the remote..
  • The Arduino will the eavesdrop on the communication between the remote and the lamp and will learn the addresses of  lamp and remote.
  • The command “i” will display the learned addressees.
  • With “w0-255-000-000” you should be able to set lamp 0 (zero) to bright red (R=255, G=000 and B=000).
  • With “w1-000-000-010” you can set lamp 1 to faint blue.

Its best to hardcode the learned addresses in the LiCo-Control application.

WheelColor : an example Processing application.

WheelColor is a Processing application that sends commando’s to LiCo_Control. You can set the color of the LivingColors lamp with a colorwheel. The application is simple and ugly but it contains a useful example for robust communication between Processing and Arduinio and in this case WheelColor and LiCo_Control.

Here an example using WheelColor :

Relevant files.

The schematic (as pdf).
The printlayout (as png).
The BOM (as txt).
The Arduino library for Arduino < 1.0 (as zip), library for Arduino 1.0 (as zip).
An Arduino example for Arduino < 1.0 (as zip), example for Arduino 1.0 (as zip).
A Processing example that uses the Arduino example (as zip).
The datasheet of the CC2500 chip from TI. (mirror). There are important bugs mentioned in the errata on the TI site !
The datasheet of the CC2500 module from Quasar. (mirror)
The datasheet of the 74LVC125. (mirror)
The datasheet of the LP2950 voltage regulator. (mirror)
The CC2500 and Atmel on the Arduino use SPI to communicate. TI has a  application note about SPI.

Assembling the CC2500 Arduino Shield

Errata

Please take note of the following changes and non-obvious issues :

  • The kit described ONLY works with the 1st generation LivingColors which is no longer sold.
  • I have made newer and slightly changed versions of the shield.  Little changes as far as assembly is concerned.  The software has changed : it has been upgraded to Arduino 1.0 and the output power has been increased.
  • Do NOT use JP1 en JP3 unless you understand what the do and how you intend to use them. They can be used for interrupting the Atmel when packets have been sent or received by the CC2500. This would require changes in the library.
  • The via’s of the surface mounted module are too close to the metal USB connector of the Arduino. The via’s are tented but it is best to punt some tape on the PCB just to be on the safe side after assembling the shield.

What is it ?

The CC2500 Shield for Arduino is a kit that interfaces an Arduino to a CC2500 radio transmitter – receiver.
What do you need :

  • An Arduino or Arduino clone like the Freeduino.
  • The Arduino development-environment.
  • (optionally) The Processing development-environment.
  • This kit.
  • Standard tools and skills om needed to assemble an electronics kit. At least you will need a small soldering iron, soldering tin, and diagonal cutters. A multi-meter is useful for finding errors and some solder wick or a solder vacuum. You can find various guides on how to use these tools.

Assembly.

Assembly is fairly easy :

  • Smallest parts first. In this case the two 74LVC125 and the DPAK voltage regulator.
  • If you are assembling the version of the CC2500 module with the eternal antenna, you should solder it now. Check the alignment with the holes in the PCB and the notches on the module.
  • If you have the module with the internal antenna, now is the time to solder the 8 pin header.
  • Solder the rest of the parts.
  • Make sure the IC’s are mounted correctly, pin 1 should be near the 8 pin header.
  • There are two different values resistors on the board. R2 and R3 are  680 Ohm, R4 is 10k Ohm. There is no R1.
  • The LED’s should be mounted with the cathode (the short pin) in the ground plane. The short pen should be near the prototyping area, the long pen near the resistors.
  • Do NOT mount JP1 and JP3 unless you know what you want to use them for. There is no JP2.

I have made a couple of clips showing how the prototype was assembled.

Mounting the  SMD’s  part 1.

Mounting the SMD’s part 2.

The LED’s and the 8 pin header.

The pin headers.

Testing the board.

After mounting the parts it is best to check a few things.

  • Check the top and bottom of the board for shorts and faulty connections.  Use the multi-meter to check for a short between 5V and GND on J1.
  • After that you can put the shield on the Arduino without the CC2500 module (if you have the internal antenna version). On the header for the module you should check the voltages. You should measure 3.3 V between pin 6 and pin 1. You can use the cut off pens of the LED’s to put in the 8 pins header.  S1 should reset the board.
  • If everything checks out you can remove the shield from the Arduino, place the CC2500 module on the shield and put the shield back on the Arduino.

Next : the software

The built up Arduino CC2500 Shield
Eagle3D allows you to render an image of the board.
Eagle3D allows you to render an image of the board.