Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

How to use 8051 to handle about 1MB of memory?

Status
Not open for further replies.

john2020

Full Member level 5
Full Member level 5
Joined
Nov 13, 2005
Messages
292
Helped
12
Reputation
24
Reaction score
8
Trophy points
1,298
Activity points
4,911
Dear All,

Im trying to use the 8051 to handle memory about 1MB.
Any one know how the idea to handle this, or maybe you

can tell me, where i can find the document that
explain about this.

Thanks.

john
 

r_p_sanna

Member level 3
Member level 3
Joined
Oct 18, 2004
Messages
65
Helped
6
Reputation
12
Reaction score
5
Trophy points
1,288
Activity points
569
8051 more than 64K

I dont think you ll get 8051 more than 64 K.
 

klystron

Advanced Member level 4
Advanced Member level 4
Joined
Jul 11, 2002
Messages
1,011
Helped
193
Reputation
386
Reaction score
179
Trophy points
1,353
Location
South Africa
Activity points
4,516
Re: 8051 more than 64K

For more than 64k external RAM use an I/O pin as adress line 17 to switch between two 64k banks of RAM. Using multiple I/O pins the RAM size can be increased to 1 M.
Take a look at the ADUC812 ; it can address 16 M of RAM
 

john2020

Full Member level 5
Full Member level 5
Joined
Nov 13, 2005
Messages
292
Helped
12
Reputation
24
Reaction score
8
Trophy points
1,298
Activity points
4,911
Re: 8051 more than 64K

hi klystron


Unless your processor handles that amount of memory (it doesn't) your
only recourse is to use bank switching. You'll have to design the
memory access mechanism so that you can have some part of the large
space visible in a "page" and then switch from page to page as you
need it.

The page size that you choose depends on how much of the memory space
you need for other purposes. Generally, the larger your page size the
less page switching you'll be doing. Also, you could bank switch into
either data memory or program memory or, perhaps both depending on
your needs.


regards
john
 

wek

Full Member level 4
Full Member level 4
Joined
Dec 21, 2004
Messages
239
Helped
28
Reputation
56
Reaction score
2
Trophy points
1,298
Activity points
1,991
8051 more than 64K

Now this is a very interesting situation, john2020 asking for some basic help and finally john2020 explaining it in detail... ?

wek
 

Bus Master

Full Member level 3
Full Member level 3
Joined
Dec 9, 2001
Messages
186
Helped
9
Reputation
18
Reaction score
3
Trophy points
1,298
Location
Just behind You ;-)
Activity points
1,455
Re: 8051 more than 64K

Do you need a 1MB RAM or Code memory? if RAM you can address as much as you need by following these steps:

1) connect the databus of the BLOCK RAM to a port buffer chip.
2) connect the same port to as many I/Ps of an address bus latch chips (e.g. 74F373)

3) By writing the required address to Latches chips, you can read/write data bytes through the same port after activating the control pins (R/W, CE) of the BLOCK RAM

By using this technique, i was able to interface a 6MB static RAM to an ordinary 8051 controller.
 

maadi

Newbie level 4
Newbie level 4
Joined
Nov 24, 2005
Messages
5
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,330
Re: 8051 more than 64K

use memory mapping technique but u would loose some ports
 

afti_khan

Member level 2
Member level 2
Joined
Oct 29, 2005
Messages
53
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,288
Activity points
1,697
Re: 8051 more than 64K

u have to use memory mapping and u'll have to use 4 bits of some other port ( like port 1 or port 3)
 

z81203

Full Member level 5
Full Member level 5
Joined
Aug 1, 2001
Messages
308
Helped
5
Reputation
10
Reaction score
1
Trophy points
1,298
Activity points
2,356
8051 more than 64K

check dallas 320 series.
 

ntfreak

Full Member level 3
Full Member level 3
Joined
Feb 22, 2002
Messages
150
Helped
6
Reputation
12
Reaction score
0
Trophy points
1,296
Location
UK
Activity points
1,252
Re: 8051 more than 64K

A simple solution is to use the ST UPSD range, they have a embedded cpld which takes care of all the pain with larger mem sizes.

www.st.com/upsd

Regards
NTfreak
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top