Maybe this will help. Check out Steve Lawther's page for an LCD tester,
there's 4-bit interface code (along with the busy check):

http://ourworld.compuserve.com/homepages/steve_lawther/charlcd.htm

Regards,

Tim Hamel


In a message dated 4/20/00 2:35:55 PM Pacific Daylight Time,
peiserma@RIDGID.COM writes:

> And i forgot to mention: this situation will mess up the LCD
>  if you go from output to input, because the pin was 0,
>  but changing it to an input makes it HiZ, which looks like
>  a logic '1' to the LCD. Scoping it confirms this. If the LCD
>  tries to pull the pin low, indicating it's no longer busy, you
>  see a 250nsec pulse that makes it to Vcc for a few nsec,
>  then decays to around 3 or 4 volts, then goes low.