I must apologize for that message being re-posted to the list in HTML. I just reconnected a mail server that has been offline for a while and this message was sent from a queue that should have been deleted! As for a follow-up: I did decide to go with the SX. The programming time of 50-100 ms per word doesn't bother me. So far I have been impressed with the ease of use. I don't mind using Win9x to develop in (I have a old 486 that I dedicated to this), however, I do wish they would supply command line tools for programming, so that I may use a real code editor instead of there IDE. I am using the In Circuit Programming feature, and find it extremely nice for prototyping. I only need a 4 pin header on the board, and have to remember to remove a jumper to disconnect the Oscillator before programming. (I got the Tristate version so I could design a way to disable it during programming automatically, but I have no clue how to do it yet!) As most of you know, not having to erase the chip prior to programming is a timesaver. I have programmed the chip 5-6 times in a 10 min. time frame. (I like to learn by making small changes and see what happens... I will probably ruin the chip by the time I'm done prototyping, it's a small price to pay for the amount I am learning.) Here's a little background on the project I am working on: The first part of my project that I am currently prototyping is for the HVAC. I will have 5 Zones, all talking to a central zone controller through a rs-485 multi drop network. The zone controller will be responsible for controlling both the HVAC unit as well as all of the dampers. The Thermostats will all be programmable from a main computer as well as from each other. (I want to be able to control/view the temp in any zone from any other zone.) They will also have the ability to display a dynamic menu/messages that are uploaded from the main computer system. The parts that I have chosen for the thermostats are as follows (This is also my base design for future nodes): 28 pin 2k Scenix SX as the MPU. ( $6.89US in singles ) CTS Tristate 50 Mhz Oscillator ( May drive more than on e MPU ) Dallas DS2401 Silicon Serial Number ( Network MAC address ) Microchip 24C32 Serial EEProm I2C ( Storage for Me nus/Messages/Thermostat information ) Dallas DS1307 Serial Real Time Clock I2C Dallas DS1621 Serial Digital Thermometer I2C Maxim MAX487 ( For Multi Drop RS-485 Network ) Optrex 16x2 LCD ( or 16x4... hav e both, not sure which will work better for the app.) I have wired everything up on a bread board(s) and have started the learning process for using each component. At this time I have been able to get a LED flashing, I HAD to do it at least once... IMHO it is the 'Hello World' program for Electronics, written multi-purpose routines for accessing the LCD, and thanks to a subscriber to the list, am currently converting a 'C' snippet to asm for reading the DS2401. I have a long way to go to get all of the functionality I am looking for, but I feel I am making progress. (I have only had the hardware for 2 weeks, and it is my first project ever.) This list has been invaluable to me in getting the courage to even get started! I do have a question for the list (I have many, but this one I have no clue what the correct solution might be.) The question(s) is... I want to supply the power from a centralized location to the thermostat s over the Cat-5 Cable that I am going to use for the data network. 1) Should I use one pair for both supply and return or 2 separate pairs one for supply and one for return? (The same pair seems like a bad Idea, but I don't quite know why) 2) Should I put a voltage regulator (7805) at each thermostat and have the supply be unregulated or have the main supply be regulated with nothing more that a Cap./resistor at each thermostat. (Would the heat from the 7805 affect the Temperature reading?) I am curious about any comments that anyone has, good or bad, about the project that I have thrust upon myself. Thanks again for everyone's past and future help. David (In over my head so much I must breath through a straw!) -----Original Message----- From: Wolfgang Kynast [mailto:wkysag@gmx.de] Sent: Friday, September 11, 1998 3:05 AM To: PICLIST@MITVMA.MIT.EDU Subject: Re: Any opinions on the Scenix Sx MPU? Hi David, > > > ... your mail address bounces, so I have to write here. Sorry to the others for that. PLEASE do no send HTML mail to a mailing list. It's an absolutely useless overhead. Regards, Wolfgang -- PIC links: http://people.frankfurt.netsurf.de/Wolfgang.Kynast/pic.htm