Data aquisition using parallel port


New member
This doesn't have anything to do with crystalfontz LCD's but I am wondering if anyone knows bout how to read data in through the parallel port.

I have built an external temperature testing circuit using an ADC0808 and a thermistor. My idea was to read the output of the ADC, which is put on the data bus, through the parallel port, then calculate the temp and display it on a HD44780 LCD.

Well I can write to the LCD and ADC fine, but I can't seem to read the data bus from either the output of the ADC or the busy flag of the LCD. I always just end up reading back the last value sent to the data port.

I read somewhere that to make the data port bidirectional you need to set bit 5 of the control port high, but I tried this and it doesn't help. I also tried setting the parallel port to EPP and also ECP in my BIOS that didn't help either.

Any suggestions would be appreciated.


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