Fluffy has now been updated to Fluffy2.

If you're considering a project that need's lots of processing power but battery consumption isn't a problem then the Scenix SX processors are for you. Ben's Fluffy programmer is an ideal starting point if you already have a PIC16C84 programmer.  So I have put together some notes on building this programmer and guidelines if you're familiar with the PIC but your not sure what is different about the SX.

Building A Programmer

Once you have had a look at the Fluffy programmer home page you will need to build a printed circuit board.  The diagram at the top of the page shows you what it should look like.  Note that my design is for the Centronics port only and I have added 1K and 1nF filter networks to each input line (D0-D5) to reduce noise with long leads and changed some of the component values.  Ben's original circuit can also be seen here.
 
 

Shown above is the component overlay for my Fluffy circuit board. Wire the PCB to a 36way Centronics socket using the pinouts shown on the component overlay (Pin 32 and the ground pins 19 to 29 are different if you use a D25).  You will need to program a PIC16C84HS for the programmer to interface with the PC so if you don't have one then have a look at my programmer PP875 (no you don't need an SX chip to make this).  If you want to make the programmer look a bit more professional then put it in a box with a front panel, the finished programmer should look something like this.

Software

To test the programmer use Ben's two test programs these can be found here in allnew.zip (41K).  If all goes well then you are ready to start programming the SX chips. You will need the fluffy assembler (32K) which includes a demo program and the fuse settings for the new SX28A and SX52B parts.
A really useful editor for constructing your code is Programmers File Editor 32bit Win95/8 PFE Ver 1.01 (608K). This is by A.Phillips, you can find the latest updates at PFE home page. Configure the 'Launch Windows/DOS Application' button to run the programmer.  This is the quickest way I have found to develop code since you are not constantly hopping between different applications. You can also configure the 'Execute DOS' command' button to run the fluffy assembler.

Documentation

Two important documents you will need are the SX18/28 data sheet (359K) and the Technical manual (1.3MB).  Although the data sheet is easier to read I have found a few errors in it that have been corrected in the technical manual.

PIC to SX conversion

A common question asked by people familiar with the PIC series of micro controllers (in particular the 16C84) is what are the main differences with the SX processor.  So after completing a couple of projects I have listed most of the important differences, I have also appended a number of common PIC instructions to the Fluffy inst.dat file which you should use, here is the full instruction set.

The page containing the differences is here.

Hardware Problems

Interrupts, in theory the interrupt controller can handle multiple interrupts.  But I have found that if an interrupt occurs before the current one has been cleared (eg: during the interrupt service routine) the interrupt hardware becomes disabled.  The only way of enabling further interrupts is to clear the WKEN_B register using the MODE and TRIS commands, problem is were do you do this ?

RTCC, when clocking the RTCC using the external pin the counter will not count unless the pre-scalar is used, thus the minimum count is two input pulses.

Links

SCENIX Home Page
Ben's "Fluffy" - A Scenix (and PIC) Programmer