Driving LED''s
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Posts: 46,084
First you will need to know if the display is common Anode or common
Cathode.
Then select a "7 segment decoder/driver", I like the 9374 for common anode
types, it uses a 15ma constant current sink so no resistors are needed, and
it latches to hold the data on the display, plus bit patterns $C$B$D$E
spells out HELP, or $CBDD0 spells HELL0.
Then there's the 9370 which will display in hexadecimal, it is also common
anode and latches.
or the 9368 for common cathode with hex output, constant current outputs,
latching.
or there is the TTL
7446,7447,7448,7449,74ls247,74ls248,74ls249,74ls347,74ls447
and countless others including cmos devices.
KF4HAZ Lonnie
Original Message
From: "naylor_nick" <naylor_nick@
> 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?
Cathode.
Then select a "7 segment decoder/driver", I like the 9374 for common anode
types, it uses a 15ma constant current sink so no resistors are needed, and
it latches to hold the data on the display, plus bit patterns $C$B$D$E
spells out HELP, or $CBDD0 spells HELL0.
Then there's the 9370 which will display in hexadecimal, it is also common
anode and latches.
or the 9368 for common cathode with hex output, constant current outputs,
latching.
or there is the TTL
7446,7447,7448,7449,74ls247,74ls248,74ls249,74ls347,74ls447
and countless others including cmos devices.
KF4HAZ Lonnie
Original Message
From: "naylor_nick" <naylor_nick@
> 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?