I would want to start by verifying both that my EP computer is
outputting a signal and that AcqKnowledge will respond to a signal.
Testing AcqKnowledge would be easy. You simply select some input pin,
then manually alternate between grounding that pin and applying some
appropriate voltage (e.g., two 1.5 V batteries in series) and see what
Testing output from EP takes a bit more work. First get yourself a
straight-through 25-pin D-connector cable, that will make your work a
lot easier for measuring voltages at the pins. I have attached a simple
EP3 program that will toggle the state of bit 0 with each key press.
Connect a voltmeter between a ground pin and the pin for bit 0 -- see
the diagram at
for guidance (I like to use pin 18 for the ground; bit 0 goes to pin 2).
Now run the program and watch the meter -- it should swing between
some low voltage (something below 1 V) and some high voltage (something
above 1 V) with each key press.
By changing the "Custom" value for the Task Event here you could test
other bits. With more cleverness you could write a test program that
toggles all the bits at once, which would allow you to be sloppier in
finding a data pin to measure; or write a test program that allows you
to enter and output arbitrary values. I leave that as an exercise.
Once you know that AcqKnowledge will respond to a signal and EP will
output a signal, the rest is just programming the signal output you
need. As Peter already said, your signal must remain long enough for
AcqKnowledge to detect it. Also, as mentioned in many other threads
here, you must reset (i.e., set to 0) your output before outputting
another value, otherwise things get garbled.
-- David McFarlane
On 2021-09-28 Tue 9:39 PM, Peter Quain wrote:
> I seem to remember having to hold the ttl signal high for a number of ms
> to get output registered in Acqknowledge. You then epoch on the step up.
> Ensuring proper pin to pin mapping is essential. Could also be something
> in the acquisition setup, so make sure the digital channels are set
> Behalf Of *Tristan
> *Sent:* Wednesday, 29 September 2021 11:33 AM
> *To:* E-Prime
> *Subject:* E-prime interface to AcqKnowledge/Biopac