| Author |
Message |
funkymunky
Guest
|
 Posted:
Wed Dec 29, 2004 8:54 pm Post subject:
parallel eeproms and 8051 |
|
|
Hi..
Im new to embedded systems, iv started with the 89c51 uC. Ive never
used a parallel eeprom with the 89c51, thought iv used a serial one
with the i2c protocol (and had a tough time in getting the thing to
work, using sdcc :-( ).
My question is..can only a parallel eeprom be used to extend the RAM??
seems logical, or else how would the uC generate the address on its
own??
Also, can some part of the code be in the on-chip flash and the
remaining in an external serial eeprom?? again, how then would the uC
know the address to find the remaining lines of code?
Finally, could u point me to some good places where i can find info on
interfacing the 8051 types to a serial eeprom. How about bus arch too..
Im googling for this info too, in case u plan to flame me for not doing
that :-)
Thanx in anticipation
Mayank |
|
| Back to top |
|
 |
Tim Wescott
Guest
|
| Posted:
Wed Dec 29, 2004 10:19 pm Post subject:
Re: parallel eeproms and 8051 |
|
|
funkymunky wrote:
| Quote: | Hi..
Im new to embedded systems, iv started with the 89c51 uC. Ive never
used a parallel eeprom with the 89c51, thought iv used a serial one
with the i2c protocol (and had a tough time in getting the thing to
work, using sdcc :-( ).
My question is..can only a parallel eeprom be used to extend the RAM??
seems logical, or else how would the uC generate the address on its
own??
|
Only parallel EEPROMs can be used to extend the "native" RAM. Serial
EEPROMs are pretty much just nonvolatile storage devices.
| Quote: |
Also, can some part of the code be in the on-chip flash and the
remaining in an external serial eeprom?? again, how then would the uC
know the address to find the remaining lines of code?
|
Not in a serial EEPROM, unless you load the code out of the EEPROM and
into RAM for execution.
| Quote: |
Finally, could u point me to some good places where i can find info on
interfacing the 8051 types to a serial eeprom. How about bus arch too..
|
Your brain. Just study the serial EEPROM data sheet and think about how
to bit-bang it (or get an 8051 with an SPI port and use a compatible
EEPROM).
| Quote: |
Im googling for this info too, in case u plan to flame me for not doing
that :-)
Thanx in anticipation
Mayank
|
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com |
|
| Back to top |
|
|
funkymunky
Guest
|
| Posted:
Wed Dec 29, 2004 10:35 pm Post subject:
Re: parallel eeproms and 8051 |
|
|
okay okay...i got that..another question:
out of i2c and spi, which standard is more popular? any specific
reasons for it? |
|
| Back to top |
|
|
funkymunky
Guest
|
| Posted:
Wed Dec 29, 2004 10:44 pm Post subject:
Re: parallel eeproms and 8051 |
|
|
Okay, got that..one more thing: out of spi and i2c, is any one of them
more popular...if yes, why? |
|
| Back to top |
|
|
Tim Wescott
Guest
|
| Posted:
Wed Dec 29, 2004 10:45 pm Post subject:
Re: parallel eeproms and 8051 |
|
|
funkymunky wrote:
| Quote: | okay okay...i got that..another question:
out of i2c and spi, which standard is more popular? any specific
reasons for it?
No, because they address different concerns. Depending on the project |
one may have occasion to use SPI, I2C or both.
If you want to hook up a small, fixed number of peripherals to a
microprocessor then SPI is much simpler to use. If you want to hook up
a large number, or an unknown number, of peripherals to a microprocessor
then I2C can't be beat.
Of course sometimes you have a peripheral that you must use that only
comes with one interface, and then you're stuck.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com |
|
| Back to top |
|
|
Jim Granville
Guest
|
| Posted:
Thu Dec 30, 2004 3:11 am Post subject:
Re: parallel eeproms and 8051 |
|
|
funkymunky wrote:
| Quote: | Okay, got that..one more thing: out of spi and i2c, is any one of them
more popular...if yes, why?
|
Look at the vendors web sites [Atmel, Ramtron etc ] and you get
an idea of what is available( and thus consumed ).
i2c uses fewer pins, so you can get SOT23 i2c memories, but i2c
tops out at 400KHz/1MHz/3.4MHz, with very few devices around
that work to the latest 3.4MHz ( I have not seen a uC yet that specs
to 3.4Mhz i2c)
SPI is much faster, so can go to 50MHz on newest devices.
So, for the largest memories, that need wider pipes, SPI is more
common than i2c.
Sometimes, you can find both: the AT17F FPGA loader devices from Atmel,
pgm like i2c, but read like SPI...
-jg |
|
| Back to top |
|
|
|
|
|
|
FAQ
Memberlist
Register
Profile
Log in to check your private messages
Log in