Well, sometimes it is better to be outfashioned, or if you want, conservative... Could save a lot of troubles.

Yes, the '51 parts Atmel "inherited" from Temic have a very smart programming scheme, where during writing the whole block gets erased while the original content remains stored in an internal "cache" and then rewritten, all in hardware and completely transparent to the user. From the user's point of view this is the same as having a bitewise programmable memory. So erasing the whole memory before programming is unnecessary and redundant.

Nevertheless, if writing occurs often and endurance is of concern, extra care must be taken (although the 100k endurance is pretty impressive and is probably sufficient for the vast majority of applications). The best thing to do is to write a complete block at once, reducing the erasure/rewrite cycles. This has implications also to the host software - it should send the data to the bootloader aligned to blocks. Flip does exactly this, reformatting the hexfile to 128-byte records. If writing custom "host" program or a custom bootloader, this "limitation" should be perhaps kept in mind.


Jeroen, just out of interest, you mentioned that Atmel contacted you with regard of the error in bootloader you discovered - did you asked their support, or was that Atmel who contacted you first?

Jan Waclawek