| ??? 02/26/08 16:50 Read: times |
#151491 - The value of PSEN Responding to: ???'s previous message |
Richard Erlacher said:
Perhaps all it needs is to be able to disconnect the nPSEN signal from the pin, electronically, once the internal FLASH is programmed.
Mightn't that be enough? In some (most? all?) processors, /PSEN is suppressed during internal operation. And some have a bit to also suppress ALE for EMI considerations. I don't see how knowing the state of /PSEN or ALE would help me crack a processor. I can always know the processors state in the instruction cycle by counting clocks from the release of reset. And its presence or absence wouldn't matter if I had opened the part to read the flash. |
| Topic | Author | Date |
| Obtaining maximum code security | 01/01/70 00:00 | |
| Worth it ? | 01/01/70 00:00 | |
| Protection with Patents | 01/01/70 00:00 | |
| the value... again... | 01/01/70 00:00 | |
| "OCR"ing a Design | 01/01/70 00:00 | |
| It's a brave man | 01/01/70 00:00 | |
| Specialist secure micros | 01/01/70 00:00 | |
| this is a different form of security | 01/01/70 00:00 | |
| Huge NREs? | 01/01/70 00:00 | |
| What if you don't bond out nPSEN? | 01/01/70 00:00 | |
| why not drop !EA | 01/01/70 00:00 | |
| Don't Drop !EA! | 01/01/70 00:00 | |
| Couldn\'t you do that in another way | 01/01/70 00:00 | |
| Eliminating /EA | 01/01/70 00:00 | |
| The value of PSEN | 01/01/70 00:00 | |
| not only... | 01/01/70 00:00 | |
| Brute-force copying | 01/01/70 00:00 | |
| well, maybe... | 01/01/70 00:00 | |
| Erase on tamper detect | 01/01/70 00:00 | |
| Make the chip hard to access | 01/01/70 00:00 | |
| It's quite impractical... | 01/01/70 00:00 | |
few thousand dollars ... Not at all | 01/01/70 00:00 |