ICE200 and Xram

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

Hi,
I wondered if using AVR Studio and the ICE200, will it emulate an 8515 with external RAM. My code uses external Xram to store some variables, however i'm not sure if the ICE200 will do that?
Thanks,
Colin

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

BTW, I wondered if there is a way to "test" the xram connected.

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

ICE200 will emulate 8515 with all its features. Interfacing the XRAM will be identical to using a real 8515 device

Bjorn

admin's test signature
 

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

Hi,
Ok, thanx! I thought it would. My program dosn't seem to be running as it should (simulates fine), so it is probably a problem with the external XRAM connected, thats why i wondered if there was a way to test it.
Thanks!
-Colin

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

there is no way of testoing the connected RAM than to write a RAM test program that is run on the ICE200. Write a simple program that strores a value to every location of the RAM and reads it back. E.g. write 0x55 to a location and read back. then write 0xAA to the same location and read back. If OK increment the pointer to the next Ram location. then you test all bits. this is not a GOOD ramtest but it works.

NOTE: The 8515 XRAM interface has a holdtime of 0ns. Many RAM circuits require larger holdtime. Check the RAMs datasheet. A way to patch this is to place series resistances on the data lines from the 8515. together with the IO capacitances this creates a slightly larger hold time. I always put 33R resistance in series with the data lines, and alternatively place a cap of a few pico from the dataline to ground (after the resistor).

Bjorn

admin's test signature
 

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

Hi,
Okay, i'll give that stuff a shot. Thanks!
-Colin

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

Hi,

I don't know whats wrong. I'ved added some resistors and some caps to lengthen the data pulse Didn't work either. I wrote a tiny program to test the xram, still didn't work. I'm not sure whats wrong. There is data on the lines, according to the logic probe. I switched RAM chips (i had these chips surplus), still nothing changed. I've decided that these chips are just not going to work.
Thanks so much for your help!

-Colin

PS: I'm using BASCOM, so i know that the routines are fine, as other people have got it to work.

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

Are you susre you have the RAM connected right? (all CE lines etc.) If you could post (or mail me) the schematics and code maybe I could help. I Have used ICE200/8515 sveral times with XRAM and had no problems. Which XRAM do you use?

Bjorn

admin's test signature
 

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

Hello,
I've attached my schematic i'm using (slightly modified, this is for an unavalible RAM). I'm suing the AS7C256, made by alliance.(256k chip, don't need all that space). Its pulled from a computer, but i have 3 of them (only need 1). I've checked all the lines, they are good. There is activity on the RAM lines. It could be BASCOM-AVR not likeing the RAM chip i'm using, not sure.
Thanks so much for your help!!!!!!!
-Colin

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

Hmm... no attachment in sight ;-) You could send it directly to me at bbrandal@netcom.no

admin's test signature