so for interfacing this i am using multiplexing technique. but even after using this technique i am not able to interface because the pins are not enough because
i have 8 analog inputs for pic and they being used for inputs
and four for bcd to seven segment and 16 for each digit
and i am left with 4 pins
and stiil i need pins for displaying negative led for temp and the pins are not enough.
please help me any technique to interface these seven segment displays
thank you.
If you use 74HC595 you need only 4 pins of your uC (SerialData, Clock, Latch, OutputEnable) and you can cascade as many displays as you wish, no mind bogling multiplexing etc.
Other option u can use scroll type only using 3 or 2 seven segments.
If u wants to use 3 7-seg method then fist segment for displaying the sensor no and next 2 segments for displaying the temp of that particular sensor. Accordingly place first segment and next two segments with little bit space.
If u want to use 2 7-seg method then u need to use 8 individual LEDs or LED array to display the sensor no. and the 7-seg can be used to disp the temp.
74154 pulls only one segment to low at a time but for multiplexing i need all segments to low and the display which has to be changed shud b high....im little bit confused again:-?can u suggest me how to do it
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yes tat's a good idea mr.jpsganesh but im doing this for a friend who want to c all the displays and compare them so i cant use scroll type..
anyways thanks for the suggestion
74154 pulls only one segment to low at a time but for multiplexing i need all segments to low and the display which has to be changed shud b high....im little bit confused again:-?can u suggest me how to do it
In that case there is the 4514 IC (1-of-16 decoder/demultiplexer with input latches). The decoded pin is high.
2.
You can add an inverter gate after all 16 output pins of the 74154 or 74LS154. You would need 3 hex inverter IC's. (Two gates would be left over.)
3.
It is also possible to construct a 1-of-16 decoder from two 3-line to 1-of-8 decoder IC's (74138, 74LS138).
(You would need to add 16 inverter gates on the output pins.)
**broken link removed**
4.
This Edaboard thread talks about using 2-line-to-4-out decoders.