External memory

Go To Last Post
12 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi all,

I need some tips about external memory which is conected on ATmega 128.
I was use IS63LV1024-12JL (3V) on STK501 board and everthing was fine..
Now I use IDT71024S12YG (5V)with 74HCT573 (Ti)latch on my board with same connections (only pinout is diferent)like on STK501, and I can write and read anything from it.
I was change CPU and memory, only latch was not changed (becouse I do not have it another).
Wait states and port pull-up's changed to but with no effects...

Any help is welcome.. :cry:

Thanks in advance.

G.P.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

what's your clk freq?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Did you connect cs1 to GND?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

You could start by posting your schematic.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,

Used crystal is 11059200 Hz.
CS1 is on GND throu Atmega's port PB.6
CS2 is on +5V.

Last Edited: Mon. Jun 11, 2007 - 05:49 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

does the d-ff ever clock in the data with that large a rc time?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

With IS63LV1024 memory everything works fine (and with 16 Mhz crystal ), so there is no reason for IDT to not work...

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Which Vcc for the Mega128, the memory and the HC473 ?
Mixed up 5V and 3.3V devices?

Maybee HCT473 could solve the Problem.

Have a look with an oscilloscope an the signals.

hws

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Mcu and HCT are on +5V.I will trace signals and post what I find out.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,

Signals on A2,3,4,5 of IDT after HCT573 (+5V):

Attachment(s): 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

and signals on A7 IS after HC573 (+3V STK501):

Attachment(s): 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi ,

Find error on LE pin HCT573 was to big cap. 100n!

Here is pic with 100 pF cap. on LE pin. Same thing is
and with A0-7 pins, if you wona reduce spikes just put
100 pF cap. on desired pin and GND!

Thanks all for help!

Attachment(s):