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>
2 comments:
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
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.
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