boot EEPROM size

Ryan J

Do i have to use a 32 KB EEPROM (24LC256) to boot from, or can the propeller use the first 32 KB of a larger EEPROM, like the 24LC1025? The documentation doesn't seem to say anything about compatibility with other EEPROM chips for the boot procedure.

Post Edited (Ryan J) : 12/2/2009 7:25:51 PM GMT

mctrivia

i use a 64k EEPROM for my propmodules. the boot loader will just read the first 32k and ignore the rest.

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24 bit LCD Breakout Board now in. $21.99 has backlight driver and touch sensitive decoder.

JRetSapDoog

Parallax actually offers a surface mount version of a 64KB chip, part no. 602-10001:·

It would be compatible for booting (with room for extra data) because as the page for the part says:

"The AT24C512 provides 524,288 bits of serial electrically erasable and programmable read only memory (EEPROM) organized as 65,536 words of 8 bit; it is the EEPROM that is used for the SchmartBoard kit."

The SchmartBoard kit uses this chip and a surface mount Propeller.· Offhand, I'm not aware of them offering a through-hole version; however, this surface-mount chip is only 8 pins, 4 on each side.

P.S.:· Here's the datasheet: http://www.parallax.com/Portals/0/Downloads/docs/prod/compshop/602-10001-32KBEEPROM(SMT).pdf

Mike Green

Several Propeller boards use a 64KByte EEPROM like the Protoboard. Some use a 128K EEPROM like the Hydra. A few people have been using Ramtron FRAM in 32KByte and 64KByte sizes including their multifunction chips (EEPROM + RTC + Watchdog timer + Serial number).

Mike Green

Be careful. The FM33256 is an SPI part, not I2C. You can use it with a Propeller, but not on pins 28/29 for a boot EEPROM. You'd want to use something like the FM31L278.

JRetSapDoog

Whoops!· Big mistake!· Thanks Mike.· BTW, I deleted the post so as not to further trouble anyone, but perhaps I should have edited it instead.·

Links:· Here's the info. page for the I2C FM31L278 32KB part and here's the datasheet.·

The backup current (supplied by·battery or capacitor) for the Real Time Clock/Calendar is stated as under 1 µA.· The link states that·the RTC·"uses [noparse][[/noparse]a] standard 32.768 kHz crystal (12.5pF)" which would be hooked up to pins 10, 11 according to the datasheet·for the chip.

Guess they don't have a 512Kb/32KB part (yet), based on their "Processor Companion" page.


Post Edited (JRetSapDoog) : 12/6/2009 10:00:55 PM GMT

Toby Seckshund

I am just bolting a Dracblade together. I reached into the bit draws and first up was a 256Kb, I thought "Will do" then doubt set in, as it is soldered, not socketed, 512Kb just in case a clever/vital use for te extra 32KB gets mentioned, tomorrow.

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JRetSapDoog

BTW: I'm curious if anyone knows offhand (without breaking out a calculator and datasheets) the approximate difference in speed for accessing, say font data, from EEPROM, HUB RAM and Prop ROM, calling the fastest (lowest access time) as 1X. I'm toying with the idea of putting a font in part of the second 32KB of a 64KB EEPROM. Hmm, while we're at it, maybe throw in an SD card for comparison, though it seems that the SD object for that keeps getting faster-and-faster, just a guesstimate.

VIRAND

JretSapDoog said...
BTW: I'm curious if anyone knows offhand (without breaking out a calculator and datasheets) the approximate difference in speed for accessing, say font data, from EEPROM, HUB RAM and Prop ROM, calling the fastest (lowest access time) as 1X. I'm toying with the idea of putting a font in part of the second 32KB of a 64KB EEPROM. Hmm, while we're at it, maybe throw in an SD card for comparison, though it seems that the SD object for that keeps getting faster-and-faster, just a guesstimate.

Is Prop ROM faster than Hub RAM?
Cog RAM would be 8X per each cog.
Hub RAM would be 1X per each cog.
EEPROM would be a small fraction, perhaps 1/64 X? Very slow.
In Spin, it depends and is not constant, but using a PASM Cog for EEPROM is probably close to using BYTE[noparse][[/noparse] ] WORD[noparse][[/noparse] ] or LONG[noparse][[/noparse] ],
but bit-banging the EEPROM in Spin would be that much slower again. (Correct me if I'm wrong; I could be off a few bits.)

Once upon a time, nobody thought that Serial access was fast.
Modems were between 45 and 300 baud, and people could out-type them.
Before Propellers, we used fast Parallel memory on chips which required almost all of their pins to access.
I'm sure SATA has no intrinsic speed advantages over EIDE, except for accelerating the cycles of planned obsolescence.
Until the day when 256 bit processors only need 1 pin to exchange a gazillion exabytes per second via
Quantum Tunneling and QAM and Zero Point Energy and Flux Capacitors and Memristors and Isolinear Kiloquad Memory.

Remember those huge Pentium 2 and 3 hologram bricks? And MMX?

Post Edited (VIRAND) : 12/7/2009 1:37:03 AM GMT

JRetSapDoog

Thanks, VIRAND. You said, "Is Prop ROM faster than hub RAM?" I think that implies that you guess/assume that they are the same. I didn't mean to imply differently. I simply don't know. That sounds like a good assumption, though. I mean, even if, for example, the ROM was capable of being faster than the RAM in terms of response time, there'd likely be other limiting factors with the internal busses/clocks that would make them the same. I guess that's what you're saying, though I don't really know and wouldn't be super-surprised if things differed by, say, a factor of 2 (but I'll assume they're the same, for now). Guess one could test by loading the built-in font into RAM and fetching character data from there and comparing. Anyway, the clocking probably makes them the same. Does anyone know definitely?

I didn't consider cog RAM because I had in mind something like 100 characters at 16x16 bits (32B/Char = 8L/Char), which at 800 longs would exceed a cog's RAM, although I can see how an 8x8 font would fit in under half. And, at this time, I wasn't thinking of using a "vector-based" font like the one in the graphics object. So, I hadn't really thought about cog RAM, but I'm glad you mentioned it in the interest of completeness. Thanks for your estimate for EEPROM of it being 64 times slower (1/64 hub RAM). Might be fast enough for occasionally writing to a display buffer, depending on what else a cog had to do (don't guess it'd work for updating a display on the fly without a buffer, though). Anyway, again, that's for the response. --Jim