Tuesday, October 28, 2008

The MSP430F2254 is a 2274.

MSP430F2254, a 2274 in Disguise

A few weeks back, I ran out of MSP430F2274 chips and used the pin-compatible 2254 for a few of my BSLCracker boards. After connecting a FET to program the first of them, I found that GDB mistook it for a 2274. The chip ID of a 2254, beginning at 0xFF0 and continuing as big-endian quartets, is "F2274". The photograph above, taken by Brooke Hill, confirms that the die of the MSP430F2254 is that of a 2274.

What method is used by TI to downgrade a '74 to a '54, and is it reversible? Please email me if you can shed any light on the matter.

Cheers,
--Travis Goodspeed
<travis at utk.edu>

4 comments:

blb said...

I was curious if you had discovered how TI downgrades their chips. I've also noticed the same thing with the MSP430F2616's, the programmer detects them as F2619's.

Cheers,
Barry

cspeye said...

Haven't seen the other bond wires, but the easiest way i'd imagine is to have two bonding pads that you can short together to change it. Or they have a fuse they set in memory somewhere during manufacturing.

Even if you could reverse it, they probably don't test the extra memory the 2274 has--a lot of the cost of producing a chip often involves all of the electrical / memory testing. The extra memory could have bad bits in it.

DISHCANADA said...

Brooke Hill is an undercover agent and satellite snitch and rat.

Gunther Schulz said...

Hi,

I've been working on MSP's for about 10 years or so, and having stumbled upon various MSP's that seem identical, I went on a mission to find out why.

After much digging at TI's HQ, and speaking with several of the chip designers, I dicovered the following:

the '447, '448, and '449 chip are in fact IDENTICAL silcon.

TI typically only stress-tests the Flash memory for a small size (coressponding to lower part number), brands it as lower part number, and sells it at price A.

Larger chip numbers are stress-tested for sucessively larger areas of flash, branded with larger numbers, and sold at higher price.

This practice is not uncommon for chip manufacturers (even Intel does the same for PCs).

The point is: if you want guaranteed operation for larger flash areas, you pay for the extra testing.

If you're not so picky about guarantees, get the smaller part number in the range, and stress-test the flash yourself.

I've been doing this for years, and must admit I've had some failures with this method, but on ordering in excess of 10k parts per year, the savings made way outstrip the odd loss here or there.

I suspect the same principle is true on all of TI's product range.

Regards,
Gunther