Re: [U-Boot-Users] Question about U-Boot in general and the AT91RM9200 in particular

Hello!

Sascha Erlacher schrieb:

this is not correct. As Wolfgang points out you can boot directly from NOR flash.

It depends on the BootModeSelect (BMS) pin state of the AT91RM9200.

Unfortunately due to errata #37 external NOR flash will be accessed with zero waitstates, which gives an access time of 20ns, so very fast and expensive memory has to be used. And there also shouldn't be used any external address decoders or bus buffers.

So using a serial boot ROM (Dataflash or EEPROM) usually will be the best solution. Even a very small EEPROM can be suitable because the program just has to modify bus timing for chip select 0 and jump to the "slow" parallel Flash memory.

With best regards Andreas