Hi,

I might be wrong, but does the spi library rely on interrupts ? If so it will not work inside an interrupt service routine because interrupts are disabled temporarily while an isr runs.

To get around this, just set a flag in the isr which you can test for in loop, when the flag is set, you know it's time to send your data.

Duane b

rcarduino.blogspot.com

Hi,

Nice to see you found my link. To pass more current to your LEDs, you can use individual transistors or a chip which provides six or eight transistors in a single package.

The way this approach works is that the transistor is connected in the current path of each led on the separate power circuit. an Arduino output pin is connected to the base of the transistor. When the arduino pin is low, the transistor will act like a switch in the off position. If the Arduino pin is high the transistor will act as if it is a switch in the on position. This switching between on and off works fast enough for the PWM/analogWrite that you are currently using for brightness and colour mixing.

If you search for 'transistor as a switch' you will find approaches using individual transistors, if you search for 'darlington driver' 'hex driver' or 'transistor array' you will find approaches using chips.

Duane B

rcarduino.blogspot.com

Hi,

You should have a common ground for all parts of your circuit, so the lipo ground should be common with the servo ground and the arduino ground - there should be only one ground which is easily achieved by connecting all these grounds together. See the links in my signature for a little more detail.

Duane B

rcarduino.blogspot.com

Hi,

Four AA batteries should be fine if they are powering the servos and you have something else powering the Arduino, is this what you are doing amd ae the grounds connected between the two power supplies ?

If not read the two links in my signature for whats happening in your project and how to fix it.

Duane B

rcarduino.blogspot.com

Hi,

 try short or uint8_t

Duane B

rcarduino.blogspot.com

Hi,
   If your going to use an Arduino, you might as well get it to generate the sound in the first place.

Why not just build an Audino, its nothing more than 5 pots and an Arduino.

I have added a simple amplifier using a LM386 to drive a PC Speaker from mine.

Search for Audino on your favorite video site for a few examples.

Duane B

rcarduino.blogspot.com

Hi,

   Check out the two links in my signature for an idea of whats happening in your project, why you need extra power and how to supply it.

Duane B

rcarduino.blogspot.com

Hi,
   Check the two links in my signature for an idea of whats happening and how to get around it. The examples use servos but apply to power orientated components in general.

Duane B

rcarduino.blogspot.com

Hi,
   If you have a slot car track, try it there first, you only have the throttle to deal with as the track will steer the car. Its a lot harder than it looks.

Duane B

rcarduino.blogspot.com

Hi,

    Did anyone check out the link to genetic programming, it might never fly a jumbo but its a surprisingly effective program generator in some domains.

Duane B

rcarduino.blogspot.com

Hi,
   Way back when I was very excited by genetic programming as written about by this guy in his book genetic programming -

http://www.genetic-programming.com/johnkoza.html

I wrote a simple interpreter for a lisp like language that simulated autonomous agents ran in a simulated environment, the langauge descibed the agents behaviour which survival and breeding opportunities depended on. The population should have evolved one or more effective programs for survival within the environment, it was very exciting at the time. The limitation was the relative simplicity of the environments I was able to create before completing my studies and starting work.

Thoroughly enjoyed Koza's book and all the projects I have done in genetic algorithms and genetic programming, it was a really exciting area in 1992.

Duane B

rcarduino.blogspot.com

Hi,
   Good AA batteries are surprisingly strong, I use the rechargeable ones in one of my 1/18 th scale race cars. Try ones designed for cameras and you may be surprised how good they are.

   If your project is heavy or has a lot of drag you may need to skip the AA batteries an go straight for hobby batteries. Look at LIPO batteries, they are more expensive and need a computerised charger that will also cost around 40 dollars but they are very powerful and very light.

   As AAs are so cheap to try, try them first.

Duane B.

rcarduino.blogspot.com

Hi,
   Separate power is a very good idea. You can get 7.2 volts from 6 reachargeable AA batteries, they are 1.2 volts each. While you need 7 volts of more for the regulator on an Arduino board to be able to output 5 volts, I am guessing that is you use separate power you could drive the motor shield directly with 4*1.5 non reachargeable AA batteries for six volts.

You don't mention the shield your using so I cant be sure. If you so use separate power, don't forget to connect the grounds between the two power sources and watch the links in my signature for why you need separate power in the first place.

Duane B

rcarduino.blogspot.com

Hi,
   I am not sure from your post whether the 5*1.5 batteries are powering both the Arduino and the motors, if so read the links in my signature and consider separate power for the Arduino and motors.

Duane B

rcarduino.blogspot.com

Cut a long story short -

There is an awful lot you can do with Arduino
The community support is excellent
There are lots of off the shelf libraries, break out boards and shields that can get you deep into your chosen project fast

Its easy to build your own standalone and cheap - less than 10 USD.

Its a very good feeling the first few times you build a standalone Arduino for a project, I have two on my desk now, one in an Audino Synthesizer that took a day to build and one in a RC Car/Go Kart Lap Timer, both build from just the chip and supporting components, not a ready built Arduino.

Duane B

rcarduino.blogspot.com