WP34s&Co. - an internal flashdisk

[Paul Dale]

(06-02-2014 09:14 AM)pito Wrote:  The FRAMs are getting cheaper- ie. MB85RS2MT 256kx8 ~$5.

It has been a while since I looked. That is expensive for a mass manufacturing process but okay for a hobbiest.

Quote:The exposed SPI is a good news for me (I do not posses the wp34s yet).
PS: with the FRAM you may emulate the sram - via the exposed SPI and something like 5-10MHz SPI clock you may achieve a decent r/w speed..

It will clock up to 40MHz from memory.

Putting the registers in SPI FRAM would work, although you will want the stack in the internal RAM.

You could also put program memory in FRAM, but we're pretty liberal about large memory copies in the firmware. e.g. inserting a program step involves copying the rest of program memory to make space. The CPU in the 30b is very good at memory copies & it helps that there isn't much RAM. Doing this over the SPI bus won't be much fun.


- Pauli