More RAM needed

[thomas]

Hi everyone,

I am designing a LED panel and I need few more kilobytes of RAM. I only have PCM compiler so I am stuck with 16F series. Do you have any suggestion on how to add external RAM to the PIC16F877? I think I will need parallel RAM for faster access.

REgard,
Thomas
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This message was ported from CCS's old forum
Original Post ID: 144516167

[Gerrit]

Hi Thomas,

Take a look at the FRAM parts from RAMTRON. They are drop-in replacements for the EEPROM but don't have the write delays.

Also Search the board for FRAM and 600 days ago many discutions about them.


*** Thomas I want to do somthing with LED panel also. Can you
share some source and idea's with me.

please send to gerrit@waterackers.nl


Goodluck with your design.


Gerrit





:=Hi everyone,
:=
:=I am designing a LED panel and I need few more kilobytes of RAM. I only have PCM compiler so I am stuck with 16F series. Do you have any suggestion on how to add external RAM to the PIC16F877? I think I will need parallel RAM for faster access.
:=
:=REgard,
:=Thomas
___________________________
This message was ported from CCS's old forum
Original Post ID: 144516171

[j_purbrick]

:=Hi everyone,
:=
:=I am designing a LED panel and I need few more kilobytes of RAM. I only have PCM compiler so I am stuck with 16F series. Do you have any suggestion on how to add external RAM to the PIC16F877? I think I will need parallel RAM for faster access.

I've done this, and it was quite easy, but it's costly in terms of port pins plus it needs external hardware. Still, maybe it would work for you.

Send the output of an 8-pin port (port D is easiest) to the inputs of 2 octal flipflops, 74HC374 or the like. Also send it to the I/O pins of your choice of 8-bit static RAM. The outputs of the '374s go to the address pins of the RAM. The strobe lines for the flipflops go to 2 more processor pins, and the R and W lines of the RAM go to yet more (yup, we're up to 12 port pins. Life is tough.)

Then to write, you send out the low RAM address to the port and blip the appropriate strobe, then the high RAM address and blip the other strobe. Then you put the data on the port and blip the W line. To read, you do the same but instead of blipping the W line, you set the port for the input direction, set R low, read the data and set R high again. It's all a bit cumbersome but it's simple.

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This message was ported from CCS's old forum
Original Post ID: 144516244