Picaxe or not Picaxe

J

johndk

Senior Member
I'm trying to miniaturize some of my circuits and found an SSOP-28 version of PIC18F25K22-I/SS. Which should be a 28x2. But after I mounted it on a protoboard and went to program it as a test, I found it not responding. The software does not even identify the chip. So my question is: Is a 28x2 not the same as a PIC18F25K22-I/SS even though those are the same numbers on the 28x2 chip? Or did I screw up the chip while mounting it to my protoboard?

If the answer is the former, is there a source for SSOP 28x2 chips?

Thanks,

John
 
hippy

hippy

Ex-Staff (retired)
Did you buy obtain the chip as a PICAXE chip or is it just a PIC18F25K22-I/SS you have acquired ?

Unless it was explicitly advertised as a PICAXE chip there is little expectation that it would have had the PICAXE firmware programmed into it.
 
J

johndk

Senior Member
I obtained this chip from a large vendor I usually deal with. It was not advertised as PicAxe. So I guess that answers my question. I didn't realize there was additional firmware involved.

So that brings me to part 2 of my query. Is there a source of SSOP 28x2 chips? The size is perfect for my application.
 
J

johndk

Senior Member
Is there a way to purchase the bootstrap for installation into 'bare' (non-picaxe) PIC chips? Or is there a service where I could send SSOP chips and have them loaded?
 
C

Circuit

Senior Member
There is much more to the PICAXE firmware than just a bootloader. Furthermore, it is the small premium added to the cost of the blank PIC chip that provides the income for Revolution Education; the remaining software is free. Therefore you are not going to get your hands on the firmware. If your requirements are sufficiently large then it might be worthwhile contacting Revolution Education and seeing if you can negotiate a deal to program up your required number of PICS, but I suspect that this number would be fairly considerable before they would undertake such a task; its not going to happen for a handful.

One possible compromise solution is to step back a couple of years in PICAXE development when Programming Editor would convert the program into assembler for loading directly into a blank PIC using their PIC Programmer ( http://www.picaxestore.com/index.php/en_gb/bas800.html ). All this is still available. The only problem is that the software stopped development at the PICAXE28A - the PIC16F872. This chip does, however, appear to be available in the 28 pin SSOP package that you require ( http://uk.rs-online.com/web/p/microcontrollers/8248746/ ) You would have to arrange your own connections between the BAS800 and your chip, but it seems to be quite feasible. The only restriction that I can think of is that the range of operation on the old PICAXE28A is obviously more limited than the latest PIC version - e.g. PORTA = analogue input; PORTB = output; PORTC = digital input.

Have a look at Programming Editor 5.5.6 - the last version of the software that will support conversion to assembler and see if it would work for you. PICAXE Manual 2 still lists the 28A next to all the BASIC commands that are available.
 
A

AllyCat

Senior Member
Hi,

johndk said:
Is there a way to purchase the bootstrap for installation into 'bare' (non-picaxe) PIC chips? Or is there a service where I could send SSOP chips and have them loaded?
Click to expand...
Most of the answers are towards the end of the FAQs , and in particular:

"Can you reprogram my microcontroller?

We do not accept microcontrollers from unknown sources due to the correct storage/handling procedures required by these devices. We use gang programmers costing several thousand pounds to program the bootstrap code into the blank microcontrollers, and so must protect this expensive equipment from damage. It is also likely that if we did offer this service the handling cost would end up more expensive than new PICAXE microcontrollers anyway!
- See more at: http://www.picaxe.com/FAQs/Fault-Finding/#sthash.2Xl4Z3l0.dpuf "

However, Rev Ed will program "production" quantities with your code into new chips, and we have been "promised" that the ability to program blank PIC chips is planned for a future version of PE6, but I wouldn't hold my breath. ;)

Cheers, Alan.
 
J

johndk

Senior Member
Thanks for all the info. As I only bought 2 'bare' chips for testing, it's no great loss. I was hoping there was a service whereby I could have the firmware installed on SSOP chips, but it wouldn't be production quantities. So it looks like I'm out of luck on the smaller size until RE decides to offer that size. I will, however, look into the possibilities of BAS800 to see if I can make some use of the chips I purchased. But that will have to wait until I have some 'play time'.....
 
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