Thread Number: 40622
My Electronics Project (Proper One) 		[Down to Last]

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Post# 600914   6/4/2012 at 08:53 (4,343 days old) by henrypeter21 ()        

As you might know I have previusly started threads about my project. That was when I was trying to run before walk though. This time, I would like to share a book called 'PIC in Practise, A Project Based Approach'. This is an excellent book. When I read a chapter on How to make a Single Digit Display, I Hit on the idea of making my own washing machine PCB (Printed Circuit Board) using a 20 Pin chip. For my Birthday I got a 20 Pin chip and experimental board and have started to make a diagram. I will only have three or four Basic Cycles to begin with, and my machine is planned to be totally Eco - Powered. In other words, I hope to make my machine only with Eco Wash Programmes, until I get a biggger chip, which I will then add a heater and thermostat and use warm cycles. Here are the components which will be wired to the chip:

Chip Power Supply (5V dcNCLR)
- AO
SWITCH0 - 1
SWITCH1 - 2
SWITCH2 - 3
SINGLE LEVEL PRESSURE SWITCH
DRAIN PUMP TRIAC3
SOFTNER WATER TRIAC2
COLDWATER TRIAC1
DOOR LOCK RELAY
MOTOR ISOLATION RELAY1
ARMATURE CHANGE OVER RELAY2
SPEED CONTROL RELAY3 (Normal Wash)
SPEED CONTROL RELAY4 (Gental Wash)
SPEED CONTROL RELAY5 (Distribute)
SPEED CONTROL RELAY6 (Slow Spin 400RPM)
SPEED CONTROL RELAY7 (Fast Spin 800RPM)


I Am intending to find a speed controller from the 1980s, Preferably the Hotpoint speed controller for the 95 Series. I cannot use the one from my old WM64 which was sent to the tip a while ago because the control was prebuilt into the mainboard.




Post# 601675 , Reply# 1   6/7/2012 at 04:18 (4,340 days old) by qualin (Canada)        

It would help if you could provide the model number of the chip and possibly a datasheet so we could give you ideas.

With the three switches, you could put in a BCD to decimal encoder chip, so instead of having four switch inputs, (The three switch inputs and the pressure switch input) you could potentially have eight instead. Of course, you need pull up resistors so a closed switch has a low logic state.

As well, a good place to start before you do anything on the outputs is to consider driving them with a simple LED & 330 ohm resistor to ground so that you can see what the chip is actually doing. Better to write the code first and test it before hooking up anything.

Then, for your outputs, you are limiting yourself as well because you can also drive your outputs from a BCD to decimal decoder chip. Using one of these decoders, you can have the possibility of driving 22 outputs instead of 11, using three different decoders.

When you are serious about hooking stuff up to this chip, something other than LED's, There is a whole entire circuit you have put in.

It should be like this... PIC -> Opto-Isolator -> Diode -> Pull-up circuit -> Relay ... Relays produce inductive kickback which can fry a chip if the diode isn't in place. The Opto-Isolator is there to protect the chip in the event where the diode fails.

You could possibly eliminate the pull up circuit if the output rated current on the Opto Isolator is enough to drive a relay. (You could find those.)

Besides, if you are putting this much effort into this, why not do it proper the first time and put in all of the extra cycles and temperatures that you want?

You don't need a "Bigger Chip". What you need instead is supporting digital logic to make the chip much more functional.

Go to any electronics shop and they'll be glad to sell you a catalogue of a CMOS or TTL logic datasheet book. Keep in mind that at one point in time, they used to build entire computer systems with this stuff. :-)

Discrete digital logic can do absolutely amazing things if you know what you are doing with it. The original Intel 8086 CPU only had 40 pins.

Post# 601700 , Reply# 2   6/7/2012 at 06:57 (4,340 days old) by henrypeter21 ()        
Reply to Qualin

 Thankyou very much for that qualin, Once I get myself straight with the basics i will try and do that. But the thing is, I must not run before walk. I will try and see but i think I will need a 28 pin chip at the end of the day. I cant do timers yet because I dont know how to wire one up yet. But yes it is quite achievable if i really put my mind to it. Thankyou very much.

Post# 601881 , Reply# 3   6/8/2012 at 05:04 (4,339 days old) by qualin (Canada)        

The first thing I would do is most likely become very familiar with making simple programs which toggle the outputs on and off and recognizing inputs.

For example, a good program to write would be something which counts in binary on the outputs.. then adjusts the increment delay or the increment/decrement setting depending on how the inputs are set.

Using a simple program like that, you can determine how you want your input and output logic to and from the chip to be like.

The hard part isn't so much building up the interfacing hardware. There are lots of schematics online which you can use as a guide. The hard part is coding the software.

As well, another thought you are going to have to take into account is if, you are engineering this thing so that it can extract water from the clothing, you'll have to ensure you have an out of balance sensor so it will know to redistribute.

Good luck!

Post# 602344 , Reply# 4   6/10/2012 at 11:33 (4,337 days old) by hotpointfan (United Kingdom)        
Possibility

 hotpointfan's profile picture
There is a possibility that I may do something like this in the future, with more space however, is needed.

I know for a fact that aquarius8000 is planning something like this with his WMA22P, if the PCB is the problem.

Best wishes with your project

hotpointfan

Post# 602346 , Reply# 5   6/10/2012 at 11:41 (4,337 days old) by hotpointfan (United Kingdom)        
Confirmed

 hotpointfan's profile picture
It has just been confirmed that the PCB on aquarius8000's WMA22P is the problem, not the motor.

So he will be building (with his dad!) his own PCB.

Best wishes

hotpointfan

Post# 602656 , Reply# 6   6/11/2012 at 13:21 (4,336 days old) by henrypeter21 ()        
Design

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