"interfacing" with a 486

**Cat** · 07-09-2003

Well, I'm personally a hardware guy (I'm technically in biomed engineering but 9/10s of my work is in electrical, specializing in embedded systems design) so I'm more than willing to help out a beginner in the field. Kits, though, would be somewhat expensive for me to make as the cheapest PC boards I can get would be in groups of 3 of $60 apiece. I've been working on and off on making my own PC boards at home, but I'm a bit leery about using the toxic chemicals in my apartment. Might be able to do it on my patio, but my landlords might not like it if they knew what it was I was doing. My lease doesn't exactly forbid me from using toxic chemicals on the premises, but I might not want to push my landlord's patience, especially as I'm a new tenant.

Further, a 486 is a pain because it's a huge footprint -- requires a lot of board space. PICmicro MCUs would be easier to make kits from as they require less space. Of course, if I get my home board manufacturing to work, space would not be much of an issue because copper-clad boards aren't very expensive.

Assembly languages (not necessarily x86 assembly) are needed for almost all embedded systems. PICMicro's assembly language isn't too hard to use. The nice thing with embedded systems is that the code is usually simpler to work with.

**mart_man00** · 07-09-2003

well, i wont worry about making a good looking board, ill just have a zillion wires

.

i dont not which way to go.

part of this is to learn assembly, part of it is just because its kool! the kool factor keeps on bugging me, but then again that will keep me going threw this.

i used the basic stamp as a example once, what id like to build is a timex sinclare. remember that one? i only heard about it but it was a kit computer, so its perfect.

do you remember the name of the kit you used in college? 8 bit sound good?

the electrical side of computers isnt as friendly as the software side. i cant come up with enough info, mustly becuase i need to know what im looking up.

**Cat** · 07-09-2003

Honestly, the cool factor is probably a leading cause of interest in electronics, and I think every serious electronics person DOES find it cool -- it's great to love what you do.

I'm quite adept at the hardware side (I've already got one college degree which focused largely on that area) so feel free to PM or ask me any questions. I've done no small amount of custom hardware creation, so I'm familiar with the process.

As I may have mentioned, I think the kits we used in the classes I took on the 80186 were made by my professor at the time, through the University.

Starting with an 8 bit microcontroller is a good way to go; working up to 16 bit microprocessors has only slightly more complexity, and modern CPUs will be beyond hobby capabilities.

The main issue is that at higher speeds, the underlying physical system is harder to deal with. Even at 33 MHz, how you physically route traces on a board alters the properties of the system. In basic electronics, you assume that a wire has zero resistance and no capacitive coupling to other wires, but neither of those are technically true, and at higher speeds, they can't be neglected. For example, the PCI bus inside your computer actually takes advantage of this; it uses something called reflected wave signalling to decrease the power required.

For a beginner, the PICMicro series of microcontrollers are very nice. You can build a programmer like the El Cheapo for very little money, and the microcontrollers require very little hardware. My own setup for PICMicro MCUs consists of only 7 devices -- a plug for +15V in, a 5V voltage regulator, a ceramic oscillator, three capacitors, and the MCU itself. Plus whatever devices I want to connect it to, of course.

Currently I have it set up to accept commands from a PC's serial port (required one more IC and 4 more capacitors).

PICs are nice, there's lots of info and demo code, the development tools are all free, and a programmer can be built for under $100; in fact often they can be built for under $50. Myke Predko's website (www.myke.com) has info on a home-built El Cheapo programmer which can handle a wide assortment of MCUs. The plans and the software are free.

You will certainly need to know a lot about the electical side before you're really good at this, but it's not as hard as you think. In reality, hardware is often easier than software.

**mart_man00** · 07-09-2003

In reality, hardware is often easier than software.

wtf!!!

i think ill to get this in a week or so.

**Cat** · 07-09-2003

Software is also hard to people who don't know it. Learning electronics isn't very difficult, although it may be time consuming.

Haven't used the 68HC05's myself, but they seem like popular chips. Do be warned with that particular programmer, though:

1) That seems only able to program one specific microcontroller (as opposed to a family of microcontrollers) so make sure you have a source to purchase the microcontrollers themselves from

2) That doesn't include the ZIF sockets, which can range in price from $5 to $25 apiece, depending on supplier. I'll see if I can dig up sales receipts, as at one point I found a really good supplier, but you can probably google it too.

**confuted** · 07-09-2003

1) this belongs in the "interfacing with a 486" thread.

2) using a breadboard to connect with a 486 processor would not be a good idea, and it wouldn't work. *looks around* I seem to have misplaced my spare 486 processors, but they have a ton of pins - way more than you could handle with a breadbox. Also, you'll blow the processor if you bump the voltage adjustment knob on the breadboard.

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