My first project

M

Munger

New Member
I have made the schematic for a Countdown timer but I am not sure of a few things. All the stuff is at http://munger.awardspace.com/Countdowntimer/index.php

The problems I have had are :
1. I know the segment display has to be connected to 0V but I don't know what pin must be connected.
2. I know the 4026 chip must be connected to 0V from pin 8 but there is not pin 8 on the schematic.

The buzzer on the schematic will be a piezo sounder when the circuit is made but i couldn't find the eagle library containing the sounder.

My code is also there it is very basic and i believe it will work but would you guys mind checking it for me.
 
M

Michael 2727

Senior Member
The schematic to wire up 4026s is given in the
picaxe_manual3.pdf (interfacing circuits section)

A 4026 is not the best choice to use as a Countdown
driver. It works better as a Countup driver as you only
need a single pulse to increment the display/count.
To Countdown you need to clear the display and input
the decremented value for every digit.
( this is a very slow way of doing things )
 
M

Munger

New Member
I have seen the circuit in the manual and have tried to make the schematic have the same circuit but as I said on my fist post there is not pin 8 in the schematic to connect (unlike the manual).
 
E

eclectic

Moderator
Keeping things simple.

Munger.
You've done an amazing amount of work. Congratulations.
Have you done a Syntax check?

But, first, going back over your previous postings, and the advice offered by others,
here are my opinions;

1.Wiring up a set of 4026 chips takes AGES.
2.For a four digit number, the display will run VERY slowly.
The changeover between “seconds” could take more than a real-world second,
and cause update problems.
3.The display has limited future versatility.

If you bought the AXE033 and clock upgrade, then...

1.Once it's been assembled, it has great versatility and “recycle” potential.
2.It can output a simple “serout #” value in < 50 ms.
3.It incorporates a “free” and accurate 1 second flashing timer.
4.With just four wires, it can be easily breadboard connected, when testing
and debugging.

And, after testing, if you really want, then you could build a hard wired circuit using
595 /4026 /7219 / 5450 chips.

The final choice is yours.

e.
 
M

Munger

New Member
Taking into account what you have said I think I will use a AXE033 and a clock upgrade. But I have no experience in this area. I have noticed that on all my previous threads you have given a good answer. Would you mind helping me with the AXE033 on MSN or the equivalent ? PM me with your answer.
 
E

eclectic

Moderator
AXE033

First, get the AXE033. Build it, very carefully, according to the instructions.

Then make sure it's working.

Then please post here again.

e.
 
M

Munger

New Member
I want to order everything at the same time to save on postage and packaging... what should I be getting then. The PICAXE-40X1, the LCD and the clock ??? Also I won't be able to order for about a week anyway becaue of the new year and stuff at home.
 
M

Matt_C

Member
Any reason you have to have a 40X1?
I think you can get away with a 28X1 as it looks like you want 11 button inputs, 1 PICAXE reset, 1 sounder output and 1 output for the display module.
 
E

eclectic

Moderator
Lots of cash.

Munger.
Here's a Mark 1 shopping list, dependent on your Christmas cash situation.
I've listed the Rapid codes for the non-picaxe bits. (for the pictures)
Or, if you live near a large town in GB, you could use the “M” shop.

The list may look intimidating, but, with care, you'll be using most of it for years.
I've deliberately chosen the project boards, because they work and are easy to connect.

AXE022P 28/40 board
AXE021 08 board (buy 2. You'll use them eventually)
AXE033 LCD board
AXE034 Clock upgrade
1x 28X1 chip OR 1 x 40X1 chip
2x 08M chip
AXE026 or AXE027 Download cable
AXE029 Breadboard adapter
BAT011 3 cell battery box
BAT013 4 cell battery box
BAT 016 Battery lead.
SPE002 Piezo sounder

Rapid 22-4214 Turned pin sockets
Rapid 34-0450 Jumper wires
Rapid 34-0920 Breadboard

Selection of high-brightness LED's
Packs of resistors 1000 / 4700 / 10000 Ohm
Switches for your project
AA cells

I'm assuming you can get some “hands on” assistance when you restart school.
And I'm sure that I'll have forgotten something.
e.
 
M

Munger

New Member
I have already got some of that but do I really need all that??
Also how "hands on" so you mean?
 
Last edited:
E

eclectic

Moderator
Plan B.

Munger. Plan B, but first some more questions.

1.What do you already own?
2.Is your project coursework?
If so, what are the assessment criteria?
3.Is it compulsory to design and manufacture a circuit board?
If so, then AXE033 / AXE034 / 40X will suffice as a start.

However, if you plan to proceed further, then the rest of the items I mentioned
will be useful or essential.
A pre-built project board and breadboard can be set up in minutes and possibly save
hours or days of repairs.
The two sentences above are not just my opinion, but are to be found many times on this forum.


And “hands on”?
Workshop / soldering facilities / expert advice / a second opinion / multimeters / CRO / etc.

e.
 
M

Munger

New Member
No, this its not course work. We did some picaxe last year and I found it very fun na d I wanted to continue, I just hadnt't got round to it.

I have got a tiny breadboard, a picaxe-18 and a dowload cable.
I have also got some LEDS and resistors and cables and battery boxes.
 
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