Large project simple question

[apburner]

OK. I have looked at most of the data and am somewhat confused. It looks like the smallest Picaxe I can use seems to be the 20X2. But I have not explained my needs. So here goes. The project will need 8 controllers with a minimum of 8 outputs each. However and this is what throws the wrench into to works I also want to make then all I2C slaves with a 40X2 as the master. So am I correct in my assumption or can I use smaller ones. Also I am not real familiar with the I2C bus and am wandering if what I propose is even possible. I have chosen the 40X2 because I may need to expand it some. I will need 8 outputs from the 40X2 but may need more in the future.
Thanks in advance.
Steve

 

[westaust55]

Yes you are on the right track.
Only X, X1 and X2 chips have inbuilt i2c comms capability.
Only X1 and X2 parts can act as a slave device on an i2c bus.

So physically smallest pinout is the 20 pin 20X2 to meet your requirements for an i2c slave PICAXE chip.



Now we might even raise a question as to why you are proposing to use 8 PICAXE chips as slave devices.
Can you instead, use MCP23017 i2c 2-port (=16 bits of IO) expanders. Each MCP23017 chip will give you up to 16 bidirectional pins and can be connected to a single PICAXE via i2c.
So unless your master PICAXE chip cannot handle the entire code for the project or you need localised code for speed etc, the MCP23017 could be an alternative

 

[apburner]

Sorry for not replying sooner. My main HD died the night of my post. I have a new computer now and should be OK. Thanks for you suggestion I will look into it. I am not sure if the timing of these chips will cause problems. I will see if it will work and get back. If it does it takes 4 chips off my board and that's a good thing.
Steve

 

[apburner]

I got on Microchips site and found they would send me 3 as a sample for free. So next will be testing after the wait:-(

 

[Dippy]

Just think , if you'd paid $6 or $7 to Digikey you could have had them by Friday

 

[MartinM57]

...and hopefully not be the straw that breaks Microchip's back and makes them realise (although they already know) that all the effort in picking, packing and sending free chips to people that will never buy even one of them is a waste of effort, time and money and they withdraw the facility for everyone...

 

[rgooge]

...and hopefully not be the straw that breaks Microchip's back and makes them realise (although they already know) that all the effort in picking, packing and sending free chips to people that will never buy even one of them is a waste of effort, time and money and they withdraw the facility for everyone...

I know this has been done over... but I imagine that Microchip. Maxim, TI, et al, do recognise the use of their free sample facility by 'hobbyists', but may just feel this goodwill is beneficial to the electronics industry as a whole in the long term. Maybe a little bit of philanthropy?

Surely some of the free samples, even to hobbyists, do go on to create business for them... ?

 

[BeanieBots]

Surely some of the free samples, even to hobbyists, do go on to create business for them... ?

As both hobbiest and professional design engineer, I'd say yes, but the line is quite a fine one. The cost of sending freebies is no small amount but it only takes one extra device to find its way into a high volume product to make it worth while.

What devices do I use in product? The ones I have first hand experience of.
What do I have experience of? Devices I have samples of.
Am I typical hobbiest? Probably not.

Genuine business development has no problem even paying over the odds for a one-off sample, so IMHO, it won't be long before freebies become a thing of the past.

 

[hippy]

It's a very complicated economic model giving away free samples - There's also the loss of income and turnover for the distributor who would have otherwise supplied such items.

Getting access to free samples is becoming harder and will likely become more so in future. I doubt free samples will entirely cease but manufacturers can tighten up criteria so only legitimate registered companies can apply and/or base freebie entitlement on other orders received.

 

[Dippy]

I too have noticed extra hurdles when ordering free samples.

On a couple of occasions (TI and ST) a salesperson phoned me to discuss details and future requirements before the samples would be sent.
In my case they were for legitimate projects/products, but if that happened to your average schoolboy he'd soil himself.

And once you have developed a relationship you'll find samples easier to get.

I imagine things may get tighter but freebies will never disappear.
A manufacturer would be stupid to risk a large contract by being awkward.

And sometimes the only way to get a device is via samples.
12 months ago it was almost impossible to buy an MRF49.
3 years ago same with the DS3232.

And , of course, free samples are cheaper than a newspaper advert

I remember a while back on this Forum there almost seemed to be a competition to see who could get most freebies - that really took the pee.

 

[apburner]

E-GAD. I have already got them. Asked for on 18th received from Thailand on 20th. That is quick I am in the USA. Well now to work.

Thanks for the suggestion by the way to try these. Did know they existed.
Steve