20X2 = 14X2 and 6X2

[Andrew Cowan]

Running out of code space on a 14M, and not having space for a larger chip, I've taken Dave E's idea and converted a 20X2 into a 14X2.

Works perfectly!

Andrew

 

[eclectic]

Running out of code space on a 14M, and not having space for a larger chip, I've taken Dave E's idea and converted a 20X2 into a 14X2.

Works perfectly!

Andrew

As a matter of interest,
how did you cut/saw it?

e

Oh, and if only we could cut up a 20X2
into two working chips. ;-)

 

[Andrew Cowan]

I used a dremel with a very thin cutting wheel, at ~15Krpm. Like a knife through butter .

Dust mask and goggles mandatory...

A

 

[Adamey]

Many, many years ago I used to "split" chips open to try and take a look at the die and how they were put together.

I remember doing this to several 555's. Then I decided on trying to fry a couple for fun by taking the B+ from my supply and attaching it to a small pin and tracing it across the surface of the die, creating many sparks in the process. Surprisingly, this didn't kill the chip right away and I had to give it a few tries before it quit working. I was surprised how robust those chips were.

 

[ValueAdd]

Running out of code space on a 14M, and not having space for a larger chip, I've taken Dave E's idea and converted a 20X2 into a 14X2.

Works perfectly!

Andrew

Or should that be

14X2 = 20X2 - 6BL (BL = Brainless = no functionality)

I note that while you removed 6 pins, there are 7 conductors running into the "rear" part of the chip (6BL) and 9 conductois leaving the "front" part (14X2)

 

[MPep]

The outer 'conductors' are probably associated with the lower 2 legs of the 14X2.

Well done Andrew. Think you'd need to seal the end of the chip? Just wondering.

 

[Andrew Cowan]

I just noticed that too. I think that the outer two in the 14X2 must be connected to pins 7 and 8 (the bottom two of the 14X2). It just happened that I cut the IC right on the edge of those connectors - if the cut had been 0.25mm lower, you wouldn't see them.

I guess the middle connector on the 6BL is either ground, or not connected.

Andrew

Edit: To MPep: As for sealing the end, I don't think I'd have to - the bare ends are just like unconnected pins. Although it wouldn't hurt, and I'm not sure what the centre pin is...

 

[Dave E]

Good job on the cut. Very clean. Looks much better than the way I did it which was to score it with a file and snap it off. However, it did and does work. My 14X2 has been running error free since November of '09.

The info I gathered on how to deal with the severed pins was to leave them alone. The internal circuitry is such that leaving them as default inputs was the best way to go.

Dave E

 

[premelec]

I think it's time to order the SMD chips instead of this approach - though I still advocate filing into composition resistors to move their value up a bit [and then paint them]... I thought the
ICs chips were centered in the lead frame before the plastic is put on them - not so good for power supplied to end legs...

 

[inglewoodpete]

A few months ago I used a 20X2 SMD to replace a 14M that had run out of program space. It has the added benefit of most 20X2 options being selectable by solder jumper. Eg hSerial and hi2c. Being a native 20X2, it can operate as an i2c master or slave.

The method also has the reduced risk of death by scalpel

I documented the conversion in the completed projects section as Not a 14X2 but....

I also have some spare PC boards if anyone is interested.

Peter

 

[BeanieBots]

Many, many years ago I used to "split" chips open to try and take a look at the die and how they were put together.

Many decades before digital cameras were available, we used to do that to SRAM chips, put a lens in front and make our own 'CCD' elements. Crude, but it did work

 

[premelec]

Light!

I tried to increase power handling capability of TO5 silicon planar transistors about 49 years ago by grinding the metal caps open and then immersing the transistor in FREON solvent... Watching the boiling FREON with a microscope I also noticed light emission - sort of pinkish purpley light - before LEDs were being made. BTW the dissipation capability didn't improve much :-( [I also noticed gunn oscillations on a 'scope long before they were well known with common silicon diodes while testing them - I thought it was the florescent lights or some such.

Serendipity electronics...

 

[AndyGadget]

Many decades before digital cameras were available, we used to do that to SRAM chips, put a lens in front and make our own 'CCD' elements. Crude, but it did work

I'd forgotten all about that - I did the same.

And a BC109C tranny with the top chopped off made an excellent photo-transistor.

In those days if you cracked the top off a microprocessor you could see the functional blocks inside. Nowadays a P4 is just an overall grey - No interesting detail at all.

I worked in an electronics shop as a holiday job around 1978. Red, yellow and green LEDs were around, but one day we got a handful of *BLUE* LEDs in. These cost £32 plus VAT and could just about be seen in dim room lighting. We didn't sell many.

Andy.

 

[Dippy]

We used to use Cherenkov radiation to light the office.

 

[BeanieBots]

And a BC109C tranny with the top chopped off made an excellent photo-transistor.

And an OC47 with the paint scraped off was easier to do.

 

[william47316]

Many decades before digital cameras were available, we used to do that to SRAM chips, put a lens in front and make our own 'CCD' elements. Crude, but it did work

interesting im betting it would be in mono too, nil colour.
now days some ultra bright LEDs can be used as makeshift photo diodes

 

[BeanieBots]

The element itself was indeed monochrome, but it was possible to take colour pictures by taking three pictures, each with different colour filter (red, green & blue) placed in front of the lens. Then combine to produce a colour picture.
Of course, that also asumed that you had a colour monitor on which to display such a picture!

 

[william47316]

what was the resolution like
assuming 1kbit Sram thats about 1024 mono pixels

 

[BeanieBots]

Good enough to work out how many fingers were in shot
Irrespective of any lens, focus was never very good because adjacent cells would 'leak' into each other. Also, intensity would vary from cell to cell but that could be compensated for in software.
We were happy with 16X16 pixel pictures