In SX Microcontrollers, SX/B Compiler and SX-Key Tool, hpham wrote:

Try adding in a pause after you select the chip to give the chip time to stabilize.  Also increase the pulsout a bit too so that the 8255 can see the pulse.
I looked at the datasheet and noticed that the minimum timings and they are all in the ns range which is pretty small so technically your previous timings should be ok.
[code]
PortA_8255: 'Set up 8255 Port A for Output 
LOW A1_8255 'Set Address control A1 & A0 Low to set the 8255 Port A for Output 
PAUSE 50 
LOW A0_8255 
PAUSE 50 
RC_OUT = pattern1 'Set databus for pattern1 
LOW CS1_8255 'Set Chip Select Low (Active)  

[b]PAUSE 10[/b]
PULSOUT WR_8255, 1[b]0[/b] 'Pulse Write control Low (Active) for 10 us (port changes state) 
PAUSE 50 
HIGH CS1_8255 'Set Chip Select High (Inactive) - Disable the 8255 databus 
PAUSE 50 'HOLD TIME FOR 50 MS 
RETURN 

 

Look at the datasheet ( [url=http://www.intersil.com/data/fn/fn2969.pdf]http://www.intersil.com/data/fn/fn2969.pdf[/url] ) for timing information.  Also, make sure you pull the RD line high for basic output mode 0.

 

Harrison[/code]

---------- End of Message ----------


You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=150716#m151363

Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com

The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)