Robot question

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vk6bgn

New Member
Hello PICsters,

This Christmas my young bloke received a small robot called an "Escape" from who else, but Santa Claus. It comes in kit form here in Australia and seems to be well documented. However, the kit appears to use a "once only"(?) preprogrammed 78P156ELP 18 pin chip manufactured by a company called ELAN. Is there such a thing.... a once only PIC?

Not being around the PICAXE and PIC chips in general for very long. It appears that the PICAXE-18X could possibly replace this preprogrammed 18 pin chip? The preprogrammed chip uses pin 4 for the RESET, pin 5 & 14 for VSS and VDD, a 4Mhz. crystal is on pin 15 & 16. Other pins seem to be pin for pin for the I/O. Maybe this is just a coincidence that the pins are the same? Or maybe there is some sort of industry standard for an 18 pin PIC?

Why change it out? I think my son and I would have much more enjoyment by building the robot, programming it and debugging it. Rather then just building it, letting it run around the room for a while with the preprogrammed chip installed and then putting it up on the wardrobe shelf to die a slow death.

Has anyone hacked this kit and replaced the 78P156 for a PICAXE-18X chip? Is it possible?

EXTRA: Wife asked me if the robot can push the vacuum cleaner!
 
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BeanieBots

Moderator
Actually, MOST PICs can only be programmed once. They are called "OTP" one time programmable. This is because the bulk are used in devices such as your computer's mouse. No need to ever re-program in most cases. OTP devices are MUCH cheaper.

I'm quite sure you could replace with an 18X but double check pinouts and if you have enough and the correct type of I/O.

Have a look at your chip datasheet and double check.

Then keep your wife happy by building a fully autonomous vacuum cleaner.
Not a very hard robot to do. The hardest part is the cleaning side of it.
 
V

vk6bgn

New Member
BeanieBots said:
......Actually, MOST PICs can only be programmed once. They are called "OTP" one time programmable.
Click to expand...
Thanks for the advice.

Hum.... OTP "one time programmable".... I refused to believe what I was reading on the ELAN chip data sheet. Only because PICAXE, Stamp, Arduino etc. etc. is mostly all I've ever heard of. All reprogrammable.

Beanie, your example of OTP chip in a computer mouse hits the nail on the head! Who reprograms computer mice? No one does! So OTP it is. Lesson learned today, thanks.

Dippy, thanks for the link to the ELAN 78P156ELP data sheet but I've had it downloaded and printed out for a couple weeks now, thanks.

I'm still determined to change this little robot to a PICAXE. Only because we'll have weeks and weeks of educational entertainment trying to program and debug, rather then a couple of days building it right from the box. (......still studying the data sheets when I have time)

Hammy.
 
hippy

hippy

Technical Support
Staff member
Real Robots Cybot used ELAN processors. I remember looking at the chips to see if they could be replaced by PICmicro / PICAXE; their footprint is near identical, and the instruction set remarkably similar to PICmicro as well ( but not that useful to know as OTP means we'll never be programming them ).

The conclusion I came to was ( for the 18-pin I looked at ) that PICmicro was a drop-in replacement, but for a PICAXE that would depend on which lines were input or output.

The ELAN have more configurable / different I/O options ( pull-ups, pull-down etc ) so if connected to analogue circuits that may also become important.
 
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BeanieBots

Moderator
Don't know how space is available but you could make an adapter so that it is still possible to fit the original chip.
You get DIL header sockets. These crimp onto ribbon cable and plug into regular chip sockets. That would allow you to create a board which simply plugs into the socket.
 
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Dippy

Moderator
Good points. God idea BB.

Maybe make an adaptor so that you can put the original in and also eavesdrop* so you can get to grips with the I/O of the original?
Fingers crossed that the serial download pins aren't compromised or used. Maybe there is a POKE solution, but first steps are to check what is going on.

*i.e. look at pin levels with a 'scope, DMM or logic probe.
 
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