LCD compatibility for BASIC STAMP 1.....
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Posts: 46,084
Hello,
I have been building several of the example circuits for the
STAMP 1 and ran into some trouble with the SERVO tester when
used with certain LCD displays. The circuit works with a
16x2 LCD I had from another project but I would like to use
some extra sharp LM16158 displays. I can't get the sharp
displays to do anything. They are based on the HC44780 chip.
I also had some other generic 44780 based displays that
would not respond either.
Is there that many differences between the displays? If so
can the code be tweaked to use these other LCD's?
Any pointers would be appreciated. Thanks!
Robert
I have been building several of the example circuits for the
STAMP 1 and ran into some trouble with the SERVO tester when
used with certain LCD displays. The circuit works with a
16x2 LCD I had from another project but I would like to use
some extra sharp LM16158 displays. I can't get the sharp
displays to do anything. They are based on the HC44780 chip.
I also had some other generic 44780 based displays that
would not respond either.
Is there that many differences between the displays? If so
can the code be tweaked to use these other LCD's?
Any pointers would be appreciated. Thanks!
Robert
Comments
contrast bias -- that is most likely the problem.
-- Jon Williams
-- Parallax
In a message dated 10/22/01 9:20:39 AM Central Daylight Time,
rdoerr@b... writes:
> I have been building several of the example circuits for the
> STAMP 1 and ran into some trouble with the SERVO tester when
> used with certain LCD displays. The circuit works with a
> 16x2 LCD I had from another project but I would like to use
> some extra sharp LM16158 displays. I can't get the sharp
> displays to do anything. They are based on the HC44780 chip.
> I also had some other generic 44780 based displays that
> would not respond either.
>
> Is there that many differences between the displays? If so
> can the code be tweaked to use these other LCD's?
>
> Any pointers would be appreciated. Thanks!
>
[noparse][[/noparse]Non-text portions of this message have been removed]
I think you may be correct. I found the datasheet for the display:
http://fina.lly.org/electronics/LCDs/LM16158.PDF
After looking at the sheet it looks like the LCD module itself
runs at 5v but the contrast adjustment may accept up to 12v like
the backlight. For contrast I am using a 10K pot across the 5v
supply. The specs on the data sheet are not very clear. If
possible I would like to get this to work since this backlit
display did look very nice.
If you get a chance to look at the datasheet what do you think
it is expecting for the contrast connection?
Thanks,
Robert
--- In basicstamps@y..., jonwms@a... wrote:
> Check the contrast input pin requirements. Some displays require a
negative
> contrast bias -- that is most likely the problem.
>
> -- Jon Williams
> -- Parallax
>
>
> In a message dated 10/22/01 9:20:39 AM Central Daylight Time,
> rdoerr@b... writes:
>
>
> > I have been building several of the example circuits for the
> > STAMP 1 and ran into some trouble with the SERVO tester when
> > used with certain LCD displays. The circuit works with a
> > 16x2 LCD I had from another project but I would like to use
> > some extra sharp LM16158 displays. I can't get the sharp
> > displays to do anything. They are based on the HC44780 chip.
> > I also had some other generic 44780 based displays that
> > would not respond either.
> >
> > Is there that many differences between the displays? If so
> > can the code be tweaked to use these other LCD's?
> >
> > Any pointers would be appreciated. Thanks!
> >
>
>
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
On the Parallax site you will find a couple of tutorials
(pdf files) on how to connect and program the // LCD's.
The schematics are OK and the code works, at least with a
BS2sx.
Regards
ECO
Original Message
From: <rdoerr@b...>
To: <basicstamps@yahoogroups.com>
Sent: Monday, October 22, 2001 4:19 PM
Subject: [noparse][[/noparse]basicstamps] LCD compatibility for BASIC STAMP 1.....
> Hello,
>
> I have been building several of the example circuits for the
> STAMP 1 and ran into some trouble with the SERVO tester when
> used with certain LCD displays. The circuit works with a
> 16x2 LCD I had from another project but I would like to use
> some extra sharp LM16158 displays. I can't get the sharp
> displays to do anything. They are based on the HC44780 chip.
> I also had some other generic 44780 based displays that
> would not respond either.
>
> Is there that many differences between the displays? If so
> can the code be tweaked to use these other LCD's?
>
> Any pointers would be appreciated. Thanks!
>
> Robert
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
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of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
the contrast bias and the display came on. After some more
digging I noticed that many of the LCD's I have are supposed
to work on 0 to 5v and for extended range use 0 to -7v. Is
that common? I guess it will be trial and error to see what
displays I can use with only a 5v supply and which ones will
require both the 5v supply and a negative bias.
Thanks for the hint.
Robert
> Check the contrast input pin requirements. Some displays require a
negative
> contrast bias -- that is most likely the problem.
>
> -- Jon Williams
> -- Parallax
>
>
> In a message dated 10/22/01 9:20:39 AM Central Daylight Time,
> rdoerr@b... writes:
>
>
> > I have been building several of the example circuits for the
> > STAMP 1 and ran into some trouble with the SERVO tester when
> > used with certain LCD displays. The circuit works with a
> > 16x2 LCD I had from another project but I would like to use
> > some extra sharp LM16158 displays. I can't get the sharp
> > displays to do anything. They are based on the HC44780 chip.
> > I also had some other generic 44780 based displays that
> > would not respond either.
> >
> > Is there that many differences between the displays? If so
> > can the code be tweaked to use these other LCD's?
> >
> > Any pointers would be appreciated. Thanks!
> >
>
>
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
>Problem solved! You were correct. I used a -5v supply for
>the contrast bias and the display came on. After some more
>digging I noticed that many of the LCD's I have are supposed
>to work on 0 to 5v and for extended range use 0 to -7v. Is
>that common? I guess it will be trial and error to see what
>displays I can use with only a 5v supply and which ones will
>require both the 5v supply and a negative bias.
I've seen this suggestion before, about the negative supply voltage on
LCD's. I'm sorry, but I have to ask: How the heck does one supply
-5v? Sorry for the stupid question, but I don't know!
Thanks,
John
John Walton wrote:
> I've seen this suggestion before, about the negative supply voltage on
> LCD's. I'm sorry, but I have to ask: How the heck does one supply
> -5v? Sorry for the stupid question, but I don't know!
contrast. It worked!
John Leung
Original Message
From: Kevin Olalde <kolalde@h...>
To: <basicstamps@yahoogroups.com>
Sent: Tuesday, October 23, 2001 5:46 PM
Subject: Re: [noparse][[/noparse]basicstamps] Re: LCD compatibility for BASIC STAMP 1.....
> http://www.epanorama.net/psu.html#lowvoltage
>
> John Walton wrote:
> > I've seen this suggestion before, about the negative supply voltage on
> > LCD's. I'm sorry, but I have to ask: How the heck does one supply
> > -5v? Sorry for the stupid question, but I don't know!
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
supply, I'm just interested in knowing basically how it is done? Is it
directly from a power supply or from other components in a given circuit you
are building? Anyone else?
(The list has been awfully quiet today, so I don't mind a fairly worthless
post [noparse]:)[/noparse]
TIA,
John Walton
Original Message
From: Kevin Olalde [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=bwLlRqlil4dCRDfAVx4p0udtKN3b6hYEsBsYXG-uVbTVuVfRzaInBUU-eymcczckYX-IDhwOb45-Fg]kolalde@h...[/url
Sent: Tuesday, October 23, 2001 4:47 AM
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] Re: LCD compatibility for BASIC STAMP 1.....
http://www.epanorama.net/psu.html#lowvoltage
John Walton wrote:
> I've seen this suggestion before, about the negative supply voltage on
> LCD's. I'm sorry, but I have to ask: How the heck does one supply
> -5v? Sorry for the stupid question, but I don't know!
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
very little current on the contrast pin so it does not load down the
inverter in the MAX. The MAX IC's create a negative voltage using a R/C
flyback circuit.
James R. Parish
J-Tech Internet Services
J-Com Enterprises, Inc.
Original Message
From: John Walton [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=7zFBxTjq_zMoDMJwDeTfZi6lfpaeY7Dgk2s8fcQkmcIpp8vuBoOgiVzJaQEYRTDjTSZgXTWhfrGU]john@l...[/url
Sent: Tuesday, October 23, 2001 4:30 PM
To: basicstamps@yahoogroups.com
Subject: RE: [noparse][[/noparse]basicstamps] Re: LCD compatibility for BASIC STAMP
1.....
This is a great link, but I have to be honest, I've never built a power
supply, I'm just interested in knowing basically how it is done? Is it
directly from a power supply or from other components in a given circuit you
are building? Anyone else?
(The list has been awfully quiet today, so I don't mind a fairly worthless
post [noparse]:)[/noparse]
TIA,
John Walton
Original Message
From: Kevin Olalde [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=i_uGA8fn1xIXNXiKetZrjhSnOJW17T-zEHm5Vj6tF6ScQUD9qhtUuXaJwV2NZg259KO5WIAelEk]kolalde@h...[/url
Sent: Tuesday, October 23, 2001 4:47 AM
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] Re: LCD compatibility for BASIC STAMP 1.....
http://www.epanorama.net/psu.html#lowvoltage
John Walton wrote:
> I've seen this suggestion before, about the negative supply voltage on
> LCD's. I'm sorry, but I have to ask: How the heck does one supply
> -5v? Sorry for the stupid question, but I don't know!
To UNSUBSCRIBE, just send mail to:
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To UNSUBSCRIBE, just send mail to:
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straight forward. Here's a simplified description (which is about all I can
muster).
Here's how I usually do it. Grab a wall wart. Those ugly square black plastic
things that plug into the wall and connect to a huge amount of comsumer
electronics. Look at the label (or raised lettering label), it'll say something
like:
Output: 8V - 800mA (or some such) Look for one that can generate enough
current for your needs, and is a few volts greater than the voltage regulator
you're using (7805, 7905, ...)
Chop the plug off it (save it for later projects), and determine the polarity of
the wires, use a DMM that's rated for the job. Or don't chop the plug if you
have a matching connector. The label on the wall wart may also have the
polarity of the existing plug.
Use the wires from the wall wart to power a circuit like this:
http://www.hut.fi/Misc/Electronics/circuits/psu_5v.gif (create another copy of
this ciruit but use a 7905 for the -5 volts).
Watch your current needs so that you don't exceed the capacity of the wall wart
or the voltage regulator.
That's about it.
Hopefully someone will correct my gross errors in this description. And maybe
add some omitted details, like the difference between switching and
non-switching and regulated and non-regulated wall warts (and how one can tell
the difference).
Kevin
John Walton wrote:
>
> This is a great link, but I have to be honest, I've never built a power
> supply, I'm just interested in knowing basically how it is done? Is it
> directly from a power supply or from other components in a given circuit you
> are building? Anyone else?
> (The list has been awfully quiet today, so I don't mind a fairly worthless
> post [noparse]:)[/noparse]
most audio high fi.
To make a +/- output, an ac transformer, 78M15 and 79M15 ICs are commonly
used. I have a diagram showing the circuit. If you are interested, I can
scan it and email to you.
For the LCD, a ground to pin3 worked fine in my case. I don't know if all
alpha-based LCD are the same. (probably not)
John Leung
Original Message
From: John Walton <john@l...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, October 24, 2001 4:29 AM
Subject: RE: [noparse][[/noparse]basicstamps] Re: LCD compatibility for BASIC STAMP 1.....
> This is a great link, but I have to be honest, I've never built a power
> supply, I'm just interested in knowing basically how it is done? Is it
> directly from a power supply or from other components in a given circuit
you
> are building? Anyone else?
> (The list has been awfully quiet today, so I don't mind a fairly worthless
> post [noparse]:)[/noparse]
>
>
> TIA,
>
>
> John Walton
>
>
>
Original Message
> From: Kevin Olalde [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=11I5cf3nqlxrwtxrF5G2KTMnV1xpMaXLRzg_K1q7OhlkEK76riIYUiGnXgrpZOPwayj7Jww7o--6YQ]kolalde@h...[/url
> Sent: Tuesday, October 23, 2001 4:47 AM
> To: basicstamps@yahoogroups.com
> Subject: Re: [noparse][[/noparse]basicstamps] Re: LCD compatibility for BASIC STAMP 1.....
>
>
> http://www.epanorama.net/psu.html#lowvoltage
>
> John Walton wrote:
> > I've seen this suggestion before, about the negative supply voltage on
> > LCD's. I'm sorry, but I have to ask: How the heck does one supply
> > -5v? Sorry for the stupid question, but I don't know!
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
> Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>LCD's. I'm sorry, but I have to ask: How the heck does one supply
>-5v? Sorry for the stupid question, but I don't know!
If you just want to test it out, you can use a battery. The
following circuit adjusts the contrast voltage from -V, the battery
voltage, up to +5 volts:
~50kohm -v
+5 Vdd
/\/\/\/\
;
^ |
| | -v to +5
`
contrast
|
com Vss
; |
| + |
|
battery
|
v ~3 volts | |
`
'
In application, you substitute a voltage inverter like the '7660 or
'7662, to derive the - voltage from a charge pump. The 766x is made
by several companies, a jellybean part.
http://www.national.com/pf/LM/LMC7660.html
http://www.njr.co.jp/pdf/ae/ae06046.pdf
Or as others have suggested, there may be some other way to derive
the - voltage in your system.
-- regards,
Tracy Allen
electronically monitored ecosystems
mailto:tracy@e...
http://www.emesystems.com