Propeller User needs SX Help

Philldapill

I've been using the propeller for about 8 months now and love it. I'd like to use it for everything under the sun, but sometimes a simple task isn't worth the price tag of the propeller. I came across the SX today and at it's price, it seems very usable for small simple tasks.

What kind of things is this chip capable of? What all do I need to get started? Is Assembly the only language this chip can understand? I'm totally new to this chip and would like to be able to use it as well, so any beginner info would be great. Thanks guys!

T&E Engineer

The SX chip is very powerful and fast and similar to PIC type micro-controllers but much easier to learn and capable. They can use either Assembly or SX/B (SX BASIC) or both at the same time. I started with a BASIC STAMP 2 and moved up to an SX28 and later to the SX48/52. I bought the Parallax Professional Development Board (PDB) as part of·the SX Programming kit but it looks like all they carry now is the SX Tech Tool Kit with the smaller board.·The PDB·seemed high but for everything you get - it was very nice. So you will need some kind of a board such as a Professional Development Board (PDB) or SX Tech Board. You will also need a programming tool called the SX-Key or SX Blitz module.·I·highly recommend the SX-Key because it has debugging capabilities built in that the lower cost Blitz does not. Visit the Parallax website and it should be·clear. You will also use·the SX-Key software which is free from Parallax to download.··You will also probably want to pick up some resonantors from Parallax being 4 MHz, 20 MHz and 50 MHz and also a power supply for the board. You will also want some SX28 DIP ICs too. If you get the SX Tech Tool Kit it comes with everything except for the 7.5vdc 1 amp power supply that you can purchase. You might want to start with that for $90 and then later get the PDB because it has all the bells and whistles on 1 "larger" board. Very nice!

http://www.parallax.com/Store/Microcontrollers/SXProgrammingKits/tabid/140/ProductID/364/List/1/Default.aspx?SortField=ProductName,ProductName

They also sell Proto boards, which can be used for final projects for the SX28 or starting project for the SX48. The SX48 has more I/O pins and RAM and program space than the SX28 but the SX28 is in an easier to use DIP chip for solderless breadboard work that the SX48 is not. And the proto boards are very low cost too - just need that power supply (and the SX-Key·or Blitz). Keep in mind that solderless breadboard developent kits such as the PDB or SX Tech Board·offer more flexibility than the·low cost "solderable" proto boards - unless you like to solder and unsolder a lot.

Check out the SX section on the Parallax website.

Philldapill

Well, I have to say I'm once again impressed with Parallax. I looked over the SX section and it seems like a pretty good chip for a good price.

However, I've become spoiled with the 8 cores on the propeller. Can the SX output a continuous PWM signal, while updating a small 16x2 LCD screen at the same time? If so, I will go with this chip. Thanks Tim.

T&E Engineer

That should not be a problem. Another great feature about the SX chips is that they have Interrupts that the BASIC STAMP 2 micro-controllers do not. This may be how you want to achieve one of those functions. Writing subroutines and functions are key elements of SX/B too. So much can be done with these chips. I am thoughouly impressed. Also much easier to learn than SPIN too.

Also if you want to design something to have quantities to sell or give out to others, you can't beat the SX chip cost! I used to design with a BASIC STAMP 2 because it is the easiest, then convert each section over to SX/B manually. Yes you have to have an SX-Key or Blitz - but that's a 1 time investment as compared to the BASIC STAMP 2. Don't get me wrong, the BS2 is an excellent and easy to use micro-controller but the SX chips open up more door with just a little more of a learning curve.



Good luck!

Philldapill

Oh yeah, I was looking at the SX protoboards and what not, and it looks like the only components I need are the SX chip, a regulator, a resonator, and a SX-key. Not including the SX key, that's about $5 in components right there. I like that. I'm guessing this has an internal EEPROM of some kind?

Bean

It has FLASH memory to store the program and data.
But this data CANNOT be changed after the device is programmed.
If you need to store non-volitile data, you will need to add an external EEPROM.

Bean.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
"A government big enough to give you everything you want, is big enough to take away everything you·have."·· Thomas Jefferson

"It is our choices, Harry, that show what we truly are, far more than our abilities."·Dumbledore from Harry Potter

www.iElectronicDesigns.com

·

Zoot

Somebody said...
, a regulator, a resonator, and a SX-key. Not including the SX key, that's about $5 in components right there. I like that. I'm guessing this has an internal EEPROM of some kind?

Depending on the project you may not even need that much. The internal 4MHZ oscillator is quite satisfactory for many projects (if you don't have very tight timing needs like serial comms). That leaves you needing just the SX, a 10K resistor for MCLR and a .1 cap on the power rails. Even the regulator may or may not be necessary depending on supply (e.g. 2 AA with BOR26 setting).

The SX can do a lot more than a few simple tasks at once. Mostly it's a matter of need and approach.

Personally, I prefer it to the Prop (though the Prop is awesome for a lot of apps) because it's cheap, it doesn't require external memory and it has a nearly instantaneous startup cycle (nanoseconds depending on the scope of the reset code).

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
When the going gets weird, the weird turn pro. -- HST

1uffakind.com/robots/povBitMapBuilder.php
1uffakind.com/robots/resistorLadder.php

Guenther Daubach

Philldapill,

here is an example for what I'm doing with just one SX28 clocked at 50MHz:

- Generating constant period PWM output for three H-bridge motor drivers with soft-start ramps
- Handling I2C slave communications for receiving commands, and sending status data
- Reading tacho pulses from three motors, and keeping track of the motor positions
- Constantly comparing current motor positions against target positions in order to stop a motor when at target
- Monitoring the motor currents to turn off the system on over-current situations
- Checking end and reference sensor contacts for three axes
- Checking for missing tacho pulses to turn off the system when motors are blocked

This is just an example for what can be done with just "one cog" .

Nevertheless, the Propeller and the SX don't have too much in common, except that both are great and powerful controllers but on different levels.

When you are new to the SX, be prepared for some learning. In case you have used Basic Stamps before, SX/B would be the best language choice for your first SX applications. If not, I can only recommend learning the SX Assembly language at first place. This allows you to "talk to the SX" in its "native language" for fastest and most compact applications.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Greetings from Germany,

G

Steel

I think the SX is much better than the propeller in many respects. It is much cheaper, and it is capable of quite a bit. I only use the Propeller for larger products that require true multi-processing...but most functions you can get away with just using the interrupt and timers (on the 48)...