Hi,

I'm using a ADC0804 to convert an analog signal from an LM335 temperature sensor, the digital conversion works perfectly, but now i have a problem.

I would like to be displayet either on 2 7-segments displays, or to be interfaced with the parallel port.

The problem with the segment displays is that I have an 8-bit signal from the ADC, but my display drivers only works with 4-bit signal.

I think the parallel port interfacing is the easiest way, I would like to interface it directly without any additional IC's if possible. If that is imposible a small amount of common ic's or transistors would be prefered.

Its not possible for me to use any additional microcontrollers or microprocessors.

Thanks...

__________________
Best Regards.
Bo Sørensen / EFloW

 

To interface w/ 2 7 segment displays you need 2 7 seg decoder drivers. One the 1st four bits 0-3 the second, bits 4-7 With a parallel port you can decode in the reading program. You must control the R/W cycle because the 804 has 8 bi-directional ports. How were you planning to do that in a stand alone version without a micro controller? I mean if you just want a stand alone 2 seg readout w/ 0-5VDC as a input ( thru a sensor) You join pins 3 and 5 INT/WRT and fround pins 1 and 2 RD/CS.
You must hower drive each seg with its own 9368 or equiv.

 

I know i need display drivers. and that is no problem either.
But i think my solution is to use the parallel port and then write a program.

I think i'm just gonna put the parallel port in bi-directional mode, using bit 5 of the control ports and then send the data over the data ports.

As far as i have understand it's quite simple.

But I need to get some additional parts before i can play a little bit with it.

Thanks anyway

__________________
Best Regards.
Bo Sørensen / EFloW

 

Check National Semiconductor Aplication Note 460 and ADC0804/ADC0805 8-Bit µP Compatible A/D Converters.
I build one of this 4-5y ago, as I remember I used the free runing setup, and changed the A/D clock to run at lower freq.
In this days you must have a bidirectional paralel port, so just read the value and convert is to C or F.

STEVE

Attached Images

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What if we would like to use FPGA Spartan Board for seven segment display?