Hi everyone,

I am developing a bootloader that is downloading the program data through SPI to an 8051 ASIC derivate FLASH.
I have some confusion in the following thing:

How do I know wether the code downloaded to the Flash is not corrupted? I mean during the data transfare (SPI with 4Mhz speed) there is a possiblity that some errors occures.

Is the verify (read the program back) the only method where I can be 100% sure that the program was written correctly?(probability that by reading back the program and the same error occures during the transfare is nearly 0 i guess)

I am of course using 16-bit CCIT-CRC to check the whole program area (32kBytes) but by this code size CRC can't give 100% certanity about the program correctness. I could also use CRC calculation for the Flash pages (256bytes) but it would cost much more time.
On the other side reading back the program takes also time, and as usuall time is money (or at least in the production where the chips are programmed).

I don't really want to start a discussion about the CRC , I would like more to hear opinions about how other generic chip producers makes sure that the code downloaded to the program area is correct. I mean in each programming SW for generic chip there is the verify option, but you can switch it off any time.
Whitout verify how can you be sure in a generic chip that the downladed code is not corrupted?

thanx for answers in advance
greetings
Attila