SparkFun Forums

[antennaboy]

Hello,

I am new to microcontrollers and saw that there are so many different types. I am familiar with the Arduino family of microcontrollers but I also noticed that there are other types on the sparkfun website, like the picaxe microcontroller.

What is the difference between an Arduino and something like the picaxe? Do they work the same way? Is the picaxe easy to use?
Do we simply need to program them by connecting them with to an external computer?
What language do they use and do I need to download a special software to be able to program them?

I would like to build a rocket an place sensors on it (altimeter and other sensors). What steps would I follow? Do I need to have a microcontroller onboard connected to sensors and the sensors output would get recorded in the microcontroller memory? I guess I would need a very small and light microcontroller to place it on the rocket...

Thanks for any insight,
Antennaboy

[BEST2V3]

Hi antennaboy

1. The difference between the Arduino and the Picaxe is as follows: The Arduino ~$20, 16 MHz clock, 32K bit memory, that you are familiar with, uses “C” or “C++” to program. It is good but it is a credit card size unit.

The Picaxe 14M2 for example, ~$4, is a 14 pin DIP that is about 1/4 inch wide by 3/4 inch long. The clock speed in the Picaxe can be set to as high as 32 MHz but how much speed do you need?

2. Each micro controller works the same way but the languages are different and the set-up is different.

3. Once you have the Picaxe USB programming cable, Sparkfun Pn PGM-08312, have soldered in the 3.5 mm Audio Jack, Sparkfun PN PRT-08032, have installed your 5 volt power supply and have downloaded the operating system found on the PICAXE download page, the Picaxe is much easier to program and use than the Arduino.
4. The Picaxe program is written on your computer and downloaded to the chip.

5. Because the Picaxe is programmed in Basic, it is much easier to read and understand your program. Basic is easy to catch on to.

6. The Picaxe 14M2 has 8 pins that will perform 8-bit Analog to Digital Conversion for such things as temperature, humidity and altitude sensing. At 32 MHz a single ADC using the 14M2, will take 100µS. You can request 10-bit ADC Picaxe programming by using the Basic command “readadc10 C.1, W1” where C.1 is pin # and W1 is the word variable receiving the data. Of course these pins and variables can be changed. The Picaxe has a built-in debug capability that will show you the values of all of its registers where ever you want in the program.

The Picaxe uses 5 volt and can handle 20 ma per pin. The program space is limited to 2048 bytes which is about 500 lines of code— I am assuming that you have a separate transmitter that can take several inputs and modulate them on to the carrier for telemetry. The Picaxe is not fast enough to transmit directly. But if you want, the sensor values can be stored in memory. There are 512 bytes available in the 14M2 for storing data using the “poke” instruction. You are not limited to using the 14M2. There are other Picaxe chips. Choose the one that best suits your needs.

I would suggest you read the Basic Commands available at www.picaxe.com and get familiar with programming this chip should you choose to use Picaxe.