Pico Technical Support and Discussion Forum

reckface · User Joined: 01 Sep 2005 Posts: 2

I need to sample an on/off signal from channel 1 of the ADC-11. All I want is when ever someone touches a switch it notes the time. I don't really want voltage measurements just a 1 or 0.
With the sample VB project I get numerous readings of meaningless voltages even when there shouldn't be any.
1. How can I programmatically capture the time only when triggered?
2. Why do I get large seemingly random mV values when there is nothing connected to the channel?
3. Why does get_times_and_values return large (sometimes negative) numbers for the times?

Michael · Posted: Wed Sep 07, 2005 9:13 am Post subject:

Hello,

Thank you for your post.

I shall answer your questions in order.

1: Use the adc11_set_trigger and write a VB command to place a date/time stamp in an adjacent field.

2: You are picking up ambient noise.
3: As above.

If you are using the ADC-11 to capture these these ON/OFF times, you should feed a 2-2.5v supply to a normally open switch. Set the trigger threshold to the supply voltage(this must be in ADC counts!) on a rising edge.

I hope this gives you some direction.

Best regards,
Michael

reckface · User Joined: 01 Sep 2005 Posts: 2

Thank you very much for your response, you have accurately described my problem. I will try your suggestions.
I do have a further question though: How come using the same 1.5V battery, with the pico software behaves consistently without any noise issues? What I want to do is almost identical to the Pico software, except I want to do it realtime without having to export the spreadsheet to process the data.
This is the code in a timer routine (taken from sample code provided):

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