Propeller, SX or Basic Stamp? How to choose.

Brian218

Hi,

I'm still somewhat new to embedded programming, but over the past few months I've been programming with both both the Basic Stamp and the SX, and am really hooked.·Although I still have a little ways to go before mastering either of them, the programming is getting alot easier and the various examples of program code are fairly easy for me to follow.

I plan to 'upgrade' to the propeller shortly (I will still be programming with the SX/BS2) and am wondering what are some of the criteria for choosing the propeller over the SX or Basic Stamp. In other words, what can the propeller do that the SX can't.

Example, one of my future projects will be a 12 VDC heater PWM controller with 5 channels. Each channel will need to be independently adjusted for a duty cycle of 20%-100%. Would this be a practical project for the SX, or is this a Propeller project.

Thanks
BT

Mike Green

For your specific example, either the SX or the Propeller would do. Things to consider:

1) Cost. The SX is considerable cheaper than the Propeller. The chip is cheaper and the SX doesn't need an external EEPROM.

2) Speed. The Propeller is clearly much faster than the SX although the SX can be a little bit faster if you are mostly using
8-bit data and 8-bit arithmetic and the calculations are simpler (ie: a better match to the instruction set).

3) Memory. The Propeller clearly has much more RAM on-chip, but it does have to store the working program there as well.

4) Multiple processors. This is very handy. It can markedly simplify programming where you really need to have multiple
processes going on. In the case of the SX, you can simulate this using interrupts, but it complicates programming and
the overall speed has to be shared among processors.

5) Special stuff. The Propeller has the cog counters which are more numerous than the equivalents on the SX and much
more versatile. It also has the video generators and can do its own display while still having plenty of memory and
processing power available for other things.

6) Programming. SX/B has a lot of special cases. It adds a level of functionality above assembly language and the
instruction set, but it doesn't really insulate you from some of the oddities of the processor and instruction set.
Spin is much better at that and the instruction set is much more regular with fewer special cases. In addition,
having 32 bit native arithmetic (and more basic operations) frees you from worrying and/or errors because of
16-bit and 8-bit arithmetic.

Brian218

Thanks for the info Mike,

I·really appreciate your reply.

Best regards
BT

deSilva

I generally have a more sarcastic view on things than "Mild Mike"

To my observations the Propeller is used by two kinds of persons:
* One group tries to stress it to no end, using it for things where special hardware or DSPs are made for, not neccessarily more expensive... They nerve us by saying : "Look Ma, what I can do with this GPP..."
* For the other group most features of the Propeller are fairly overdone and they would be much more happy with BASCOM and an ATmega32, if the knew They ADAPT their usage to not fiully understood prefabricated "driver-objects", using SPIN only.

This is somewhat faster than the BasicStamp and - as Mike indicated already - the Propeller are 8 BasicStamps so to speak.....

The perfect use for the Propeller is a professional mixture of your own Assembly code with SPIN. But both languages have their ideosyncrasies...