8055 - analog input connection

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1

I am able to get the card working OK using Access VBA. … except…
I am trying to use the analog input.
I have placed a thermister accross GND and A1, also a Light dependent resister accross GND and A2 analog inputs.

I was expecting there to to be a reaction to changes and light and temperature, but the small test programme I wrote below reacts only to the two potentiomterss being changed.
Removing the link brings the reading down to zero.

Should there be a voltage source applied to the connections in some way?

I realise that the program below is not wonderful … but it just to witness that the 8055 reacts to light and heat changes. Once I have the expected reaction from the two devices, I hope to write something appropriate

Any advice will be gratefully received.

#######################################

Function test_card()
Dim a As Long
Dim data1 As Long

OpenDevice (0)
SetAnalogChannel (1)
a = 1
Do While a = 1
data1 = readanalogchannel(1)
Debug.Print data1
Loop

2

[quote]Should there be a voltage source applied to the connections in some way?[/quote]Yes, there should be. Here a connection diagram example:

You may use the analog output (DAC1, DAC2) of the card as a voltage source too.
Please note there are 1k5 series resistors at the analog outputs of the K8055 card.

For more info please see: doctronics.co.uk/voltage.htm

3

Thank you. I am most obliged to you.

Especially the tip of using a 5 volt source from the board

Thanks for taking the time to sort me out.

I will try this with much anticipation.