How to connectl PIC16F876 and 1024Kx8 SRAM

[salamander]

PIC + SRAM

Hallo,
I want to connect my pic (16f876) to a huge 1024Kx8 Nonvolatile SRAM(Dallas: DS1270y-100), but I really don't know, how i could manage this both on hardware(-> how to wire, ?external devices nedded?) and software(-> I mean my c code).

thanks a lot
salamander

 

[cube007]

Hi salamander,

you have interface it parallel to your PIC.

1 pin for write
1 pin for read
1 pin for cs (not necessary)
8 pins for data
20 pins (2^20 = 1024) for address pins

I think that you do not have so much pins on the pic. So you have to use a extra device (latch).
How much pins are left for the connection to your SRAM?

by,
cube007

 

[salamander]

Ok, we have enough pins for direct connection

...but can you also tell me, how I can use the memory in c then? > assuming no file-system, just a big stream....

thanks a lot for your help
salamander

 

[cube007]

As far as I know:

You have to program your own access to the SRAM.

For example to read something:

1. cs = low
2. address pins to the desired address
3. rd = low
4. read out the data pins (complete 8-bit port)
5. next address
6. etc.

by,
cube007

 

[salamander]

Ok thanks a lot,
i will go this way.... - its an relative easy job for my project

thanks again
salamander

 

[cube007]

Hello salamander,

are you sure that you have enough pin on the PIC16F876. For a direct parallel connection you will need at least 29 pins!!! But the 876 is in an 28 pin package. Perhaps you should use the 877.

best regards,
cube007

 

[mrcube_ns]

20 pins (2^20 = 1024) for address pins

2^10 = 1024
2^20 = 1048576 !!!!!!!!!!!

Mr.Cube

 

[dainis]

It is right only for address pins, but you need 8 data pins, CS, OE and WR pins ....

 

[mrcube_ns]

It is right only for address pins, but you need 8 data pins, CS, OE and WR pins ....

Ok, I agree!
My replay is only for math problem in those post.

Mr.Cube

 

[salamander]

Ok thanks,
I will solve my problem on this way....

regards
salamander

 

[cube007]

20 pins (2^20 = 1024) for address pins

2^10 = 1024
2^20 = 1048576 !!!!!!!!!!!

Mr.Cube

I'm sorry: 2^20 = 1024 k = 1 M