Small footprint RAM extension
MagIO2
Posts: 2,243
Hi ... just want to share a finding.
I found these neat FM24Lxxx and FM25Hxx datasheets. It's·FRAM from Ramtron.
FM24Lxxx is available with up to [url=mailto:256kbit@3.3V]256kbit@3.3V[/url] and can directly replace the EEPROM. It not only has read-access at the speed of 1Mhz it also allows write with the same speed. So, having the usual EEPROM and one of those using different adresses but using the same pins would be a very small footprint RAM extension for the propeller.
FM25Hxx is available with up to 2Mbit and has an SPI that allows 40MHz read AND WRITE. For the propeller that would be full speed access, wouldn't it?
Now think about having several of those chips in parallel. E.G. 8x FM24Lxxx sharing one clock. So, with 9 I/Os you have access to 256kByte FRAM at a data-rate of 8Mbyte/sec (ok, minus some protocoll overhead). But that's nice, isn't it?
I hope that I find a distributor here in germany that sells to private persons as well.
I found these neat FM24Lxxx and FM25Hxx datasheets. It's·FRAM from Ramtron.
FM24Lxxx is available with up to [url=mailto:256kbit@3.3V]256kbit@3.3V[/url] and can directly replace the EEPROM. It not only has read-access at the speed of 1Mhz it also allows write with the same speed. So, having the usual EEPROM and one of those using different adresses but using the same pins would be a very small footprint RAM extension for the propeller.
FM25Hxx is available with up to 2Mbit and has an SPI that allows 40MHz read AND WRITE. For the propeller that would be full speed access, wouldn't it?
Now think about having several of those chips in parallel. E.G. 8x FM24Lxxx sharing one clock. So, with 9 I/Os you have access to 256kByte FRAM at a data-rate of 8Mbyte/sec (ok, minus some protocoll overhead). But that's nice, isn't it?
I hope that I find a distributor here in germany that sells to private persons as well.
Comments
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--Steve
Propalyzer: Propeller PC Logic Analyzer
http://forums.parallax.com/showthread.php?p=788230
I like the idea to have non volatile RAM. For battery driven devices you can suspend the whole memory to RAM and simply continue where you stopped after wakeup - without the fear of failing EEPROM cells. During operation you can switch off the power for the FRAMs as long as the RAM is not needed.
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