Driving LED''s
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Posts: 46,084
I had a client that wanted to change his video mux to display the input that
was being used. They thought by just tapping on to the 4 bit buss of the mux
they would be able to drive a 7 segment display/driver and all would be
cool. Not the case. Much to his surprise the decimal readout he received of
coarse was 0 to 15 not 1 to 16. He needed a quick and easy fix for this. So
I used a BS2 as both an interpreter and an LED driver. Writing some code
where 4 I/O's where used to monitor the buss, I drove each segment of the
two 7 segment displays sinking them directly through the BS2. 100 ohm
resistors were used to current limit. Products have been in the field for
over a year with excellent results.
Jeff Boccaccio
Original Message
From: halalbach <halalbach@y...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, January 16, 2002 1:05 AM
Subject: [noparse][[/noparse]basicstamps] Re: Driving LED's
> --- In basicstamps@y..., "naylor_nick" <naylor_nick@y...> wrote:
> > Hello,
> > Here is the situation. I am trying to use a Basic Stamp to
> > drive a 3.5 digit LED display. Can this be done? I have no idea
> > how it coul dbe done. However, I do have an A/D converter IC that
> > also has 3.5 digit drivers on it. That is controlled with a
> > voltage, 200mV max. Can the basic stamp output a certain voltage
> on
> > a certain I/O line? Can anyone point me to a website that might
> > help me out?
>
> I have built and used a 4 digit LED display using a BS2 and 4
> 74HCT373 latches. I wired each of the displays to a latch output (7
> segments and the decimal point) through current limiting resistors.
> The latch inputs were bussed together to the BS2 so that a byte can
> be output with one instruction. I used 4 more BS2 pins to strobe the
> latches to hold the data for the LED. I then programmed the desired
> bit patterns into a lookup table. To display a character I simply
> used lookup to load the bit pattern to the output pins and then
> strobed the particular latch to hold the data. This gave me complete
> software control over all four displays.
> I realize this tied up 12 I/O pins but it was a nifty first Stamp
> project for me. I used this as an odometer for my truck to keep
> track of miles between multiple stops.
>
> Have Fun
>
> Hal
>
>
>
>
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>
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>
>
was being used. They thought by just tapping on to the 4 bit buss of the mux
they would be able to drive a 7 segment display/driver and all would be
cool. Not the case. Much to his surprise the decimal readout he received of
coarse was 0 to 15 not 1 to 16. He needed a quick and easy fix for this. So
I used a BS2 as both an interpreter and an LED driver. Writing some code
where 4 I/O's where used to monitor the buss, I drove each segment of the
two 7 segment displays sinking them directly through the BS2. 100 ohm
resistors were used to current limit. Products have been in the field for
over a year with excellent results.
Jeff Boccaccio
Original Message
From: halalbach <halalbach@y...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, January 16, 2002 1:05 AM
Subject: [noparse][[/noparse]basicstamps] Re: Driving LED's
> --- In basicstamps@y..., "naylor_nick" <naylor_nick@y...> wrote:
> > Hello,
> > Here is the situation. I am trying to use a Basic Stamp to
> > drive a 3.5 digit LED display. Can this be done? I have no idea
> > how it coul dbe done. However, I do have an A/D converter IC that
> > also has 3.5 digit drivers on it. That is controlled with a
> > voltage, 200mV max. Can the basic stamp output a certain voltage
> on
> > a certain I/O line? Can anyone point me to a website that might
> > help me out?
>
> I have built and used a 4 digit LED display using a BS2 and 4
> 74HCT373 latches. I wired each of the displays to a latch output (7
> segments and the decimal point) through current limiting resistors.
> The latch inputs were bussed together to the BS2 so that a byte can
> be output with one instruction. I used 4 more BS2 pins to strobe the
> latches to hold the data for the LED. I then programmed the desired
> bit patterns into a lookup table. To display a character I simply
> used lookup to load the bit pattern to the output pins and then
> strobed the particular latch to hold the data. This gave me complete
> software control over all four displays.
> I realize this tied up 12 I/O pins but it was a nifty first Stamp
> project for me. I used this as an odometer for my truck to keep
> track of miles between multiple stops.
>
> Have Fun
>
> Hal
>
>
>
>
> 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/
>
>
>