auction counter

[tommyb]

Trying to build a counter that could be used in an auction situation, with buttons for plus and minus in the values £5 £10 £20 £50 £100 £250. I then need a display showing the figure (5 digits should do it) and a reset to zero again, one option is a switch that increases the muliple by 10 turning the steps to 50, 100, 200 etc.
Also a small disply for the auctioneer.

Many thanks Tom

 

 

[BeanieBots]

So what's the question?
Any of the PICAXE controllers are up to the task.
The AXE033 16X2 LCD display would be an easy to use display. If you want large bright LEDs that can be seen from a distance then it could get a bit more complex.

Do you have any electronics ability?
Do you have any programming skills?

 

[Mycroft2152]

BB, getting a little gunshy?
Asking those type of questions upfont?
We usually don't find out until the 18th or 20th post.

Gee, you and Hippy must be having an off day. You asking such questions and Hippy reminding the poster to READ the instructions.

What is the world coming to?



Myc

 

[hippy]

We do really try and help and I know you are not taking a serious stab at either myself of Dippy, so no need to explain, and I'm not making a dig back.

Sometimes people just have to help themselves, or help forum members to help them. A statement of fact with no hint of a question is a particularly hard one to follow-up on. The clearer a poster can be in explaining their problem or what help they need the more constructive and helpful answers will be.

One nice thing I do find about this forum is that if people have nothing constructive to say, they tend not to say anything, and at least lead posters into framing what they want in terms which can give more to work with. I've been on forums where people will bite heads off for no particular reasons and this place is much nicer all round.

[ and yes, I know I can be overly verbose at times, and people here won't be the first to have said that ]

 

[Mycroft2152]

Yes, it was just a little bit of leg pulling.



But, you two, do have immense patience and dedication to the teaching / mentoring process, Much more than I do.

I am amazed at the responses and the depth on this forum too, and proud to be a part of it.

TANSTAAFL

Myc

 

[BeanieBots]

That's the second time Hippy has got me confused with Dippy. Not sure which emotion to attach.

 

[Dippy]

Emotion? Pleasure, Mate.

And off-thread by post 3. Is that a record?

Meanwhile, back at the Ranch: Is Tommyb simply telling us about his project - or does he have a specfic question?

He's never responded, has he lost his gavel?

And by-the-way yes, read, read and read again. You don't have to absorb it all - just know where to find it.

 

[tommyb]

Hi guys, my experence is, well I took (and passed A-level electronics, and have worked in electrtronics on and off, I have a little experiance in programming, learnt basic on my spectrum and used to copy out pages of text, never moved on to other langagues.
Back in the day (about 10 years ago) used to be pretty good at boolean)

but why am I telling you all this... my question...

What is the best way to drive five 7-segment displays, each segment would be 5x7 outputs (this is the way I have been show on inset days and training days)

I guess the outputs could go into a display driver, which one would be easist to use, I know this must seem like a really simple project, just adding numbers on in various incriments... but then a usful project that is easy to make... isn't that the best combination, compaired to a useless project that is hard to make....

many thanks for all the replies, makes a newbie feel accepted

Tom Bayley

 

 

[tommyb]

ok... Have just seen the snooker game project... question is how can the serial out drive a set of 5 7-segment displays, (the four inch high type, think they have 3leds per segment, may cause a high current drain displaying 88888)

 

[BeanieBots]

Well, I'm feeling too lazy to design your project for you but you do have a few issues that need to be pointed out.
Your 4" displays are above and beyond the "norm" regarding their drive requirements.
You need to find out what they require. For example, if they have 3 LEDs per segment, are they wired in series or parallel?
Then you need to decide if you want to design your own drive circuitry or try to find a chip that will do the hard work for you. There are plenty of drivers available but you need to check that their spec will match your displays. Google is you friend for that.
Once you have something in mind, you can then choose the best PICAXE to drive it. I would predict that you will need either an 18X or 28X depending on which direction you choose. I suggest the X series because I'm giving you a slight nudge towards using an I2C driver chip. However, you might not be able to find one that suits your displays. (Common cathode/anode, voltage & current).

For the auctioneer side, a serial LCD will be the simplest (and possibly cheapest) solution. Again, the choice is yours.

There are others here who I expect will nudge you towards creating your own driver. There is no right or wrong. The choice is yours but it is not something you can easily change once you are half way through.

 

[tommyb]

I am going to drive the displays with 4511, because of the ablity to blank the display also so £255 isn't shown as 00255, I have never built or used mutiplexing but I am sure a bit of programming will easily sort this, if any body knows common stumbling points please give me the heads up.

Thanks for all your help (BB) Yours Tom

 

[BeanieBots]

That should be OK. Count up how many I/O pins you will need to drive the whole system. You might want to consider some further decoding chips.
If your display has the LEDs in series and is common cathode, you might not get enough drive from a 5v rail without extra drive circuitry. Common anode will need external transistors anyway so a higher rail would be easy.