Posting your program would be helpful.

Here is the program. I have tried different OSC settings without luck.may try a 4 MHz crystal osc with 22pF caps.

Jason,
 Try added a brown-out option to the DEVICE line. Either BOR42 or BOR26.

Bean.

Bean,
I tried both and neither worked. I am going to add a .1 uF cap from /MCLR to GND. This will pull /MCLR to GND until the cap is charged by the 10k resistor. These are 4MHz resonators that I bought from Parallax - just wanted to add that.

I believe that the I have a bad SX28 on this protoboard. I tried everything from a crystal to different frequency resonators and nothing works - I still have to press the reset button for it to startup. It only happens on one board now for some reason. I will order some extra smt SX28's when I need more protobaords to have some spares on hand.

I ended up adding a reset button to the enclosure for this one prototype.

Hello Jason,
You should only need a 4.7K or 10K pull-up on the /MCLR line.  Perhaps there is a cold solder joint on your resistor so that it is really open instead of pulling that line high.  If it is floating that would cause problems.

Is the RTCC line disconnected?  I usually tie it to ground if it isn't needed.

Just a couple things to check.

[Quoting: "Roy Carlson"]1. I saw where you can add a dip socket over the onboard sx chip so that you can use the SX28 dip chip.  How do you disable the onboard chip that is soldered onto the proto board?

1. My first idea to "disable" the on-board SX28 chip was to un-solder it - not a good one, as the pinning of the SS and DP devices is different :-( .

2. According to the schematic (see http://www.parallax.com/dl/docs/prod/boards/SX28ProtoBDRevBschematic.pdf) there are no port connections.

3. Depends on your gusto - for breadboards, I have prepared a bunch of wires with square pins at both ends, as the breadboards do have female contacts. Therefore, I also prefer female connectors for the SX pins, similar to the Professional Development Board.

4. Again, this depends on your gusto, and the application. When exact timing is not an issue, e.g. for some first "LED-blinker" applications, the internal 4 MHz clock would be fine. When it comes to detect IR LEDs, or to modulating IR transmitters, clock speeds up to 50 MHz might be necessary.

5. The main difference is the chip - the SX48 has 16 more I/O pins but also twice as much program memory, and more variable space.

Gunther,

Thank you very much.  I have seen your posts and just received your book "Programming the SX Microcontroller" from Parallax.  I just opened the book today.

I am fairly comfortable programming in pbasic and sxbasic (logic progression) and just need to learn more about how the chip structures and byte/bit manipulations can be put to use as detectors and indicators.

My main hobby application is for running my model railroad and learning about electronics and digital logic circuits (just for the knowledge).  

Since I use to program as a hobby back in early 80's I thought I would enjoy learning how to program micros from Parallax.  From what I have seen and experienced, this is the best company for the full support you get at a novice level.

I would like to purchase a good book that focusses mainly on the SX/Basic as well since it would be easier for me to get started.  Do you have any books like this or could you recommend any?

One final request... I saw on your website info about your proto board and/or IC^2 communications.  How can we purchase any of your items?

Hello,
Actually the SX28 protoboard can be used to easily program the SX28 DIP chips.  You just need to remove the surface mount SX28 and solder in a 28-pin socket .6 inch socket.  The pads are already in place and take care of the difference in the pinouts for the two package styles.  With that you can get a 28-pin ZIF socket which is then plugged into the 28-pin socket you've soldered to the board.

There are a couple ways to remove the surface mount SX28 chip.  Both of them destroy the chip but you're mainly after the whole board and the chip isn't too expensive if you need to replace it.   If you have a sharp exacto blade and a steady hand you can actually cut the leads right at the SX28 package.  You need to be extremely careful just to cut the lead and not scratch or cut traces on the PCB.  Once this is done the leads will still be on the board.  Removing those is easy.  You just need some fresh solder.  Just run a bunch of fresh solder over the leads and the soldering iron will just wipe them off the board.  They usually stick to the sponge and some off when you wipe the iron.  Solder wick will clean up any excess solder on the board.

Alternately you can just add a little more solder so you can heat one side with the iron.  With that you can pry up on the side your warming to free it from the board.  You may then need to use the solder wick to remove some of the excess solder.  Repeat on the second side and it's off.  Solder wick will then clean up the board.

I've used this to add a 28-pin ZIF to an SX28 protoboard for programming.  I've also done this when i've had to replace an SX48 chip.  Worked both times....

Hello Robert,
thanks for the info about the SX28 proto board. I did not notice that the pads for the DIL package were in place for the SX28AC/DP, so I'm sorry for my mis-leading comment.

Hello Roy,
good to hear that you have got my book, but be warned - it's all Assembly, no BASIC. Nevertheless, it may be helpful when you are looking for information about the internal structure of the SXes, the available flags, how to configure it, etc. You can find a text about SX/B here: http://forums.parallax.com/forums/attach.aspx?a=15477.

No matter if you are using SX/B, or assembly - programming, and discovering the SX is a challenge but also much fun, and you will be amazed what can be done with the SX. You can find a lot of sample code in the download section of the Parallax site www.parallax.com, and at www.sxlist.com.

Regarding my proto boards, and other SX-related parts, please send me a PM (g,daubach@mda-burscheid.de).

Have fun!

I expect Günther's correct email address is actually g.daubach@mda-burscheid.de with a period after the "g" rather than a comma.  I do not believe a comma is a valid character for email addresses though it is close to the period on many keyboards.  I assume the inclusion of a comma instead of a period to be a typographical error.

BTW, Günther's book is a great resource.   I highly recommend it! :smile:

I've always heard great things about Günther's SX programming book and I look forward to it seeing it soon.

Roy,
I've found some really good resources on SX Basic right here at the Parallax site if you don't mind electronic document form instead of paper book form.  IE; http://forums.parallax.com/forums/attach.aspx?a=14085
The "work in progress" book being worked on by Jon is very promising and goes a long way towards getting comfortable with the SX flavor of basic.

In my opinion, the best resource yet is the "sticky"  best SX threads list at the top of this forum.

BTW:
My original interest in electronics.. (OMG... was that really 1974?) stemmed from my desire to automate my model railroad after seeing the layout in the Deutsches Museum in Munich (which incidentally makes any science and technology museum in the USA look tiny by comparison) http://en.wikipedia.org/wiki/Image:Deutsches_museum2.jpg  It requires no operators to run many trains at once.  It has been doing so since the 1970's if I remember my facts right.

Sparks,
thank you for correcting my email address - you are right, the comma was a typo, and g.daubach@mda-burscheid.de works a lot better :-) .

Robert,
guess what... The books finally arrived, so you'll have one soon.