1. StimTracker turns off when I plug the m-pod cable.

Try connecting just the cable to StimTracker, i.e. without m-pod on the other side of the cable. If it still turns off, it would indicate a bad cable. If your unit is still under warranty, contact Cedrus for a free replacement; or you can purchase a cable from the online store.

2. How can I connect my computer’s parallel port to StimTracker?

Cedrus offers a kit for this purpose; see Using an External Input Source.

3. Everything is connected correctly but I am not getting TTL output.

The first step is to isolate whether the issue is on the input side or the output side. On the input side, start by looking at the event marking LEDs on StimTracker’s front panel:

• For example, for light sensor 1, does the “1” LED light up when the light sensor is exposed to light? Try using a smartphone’s flashlight to be sure. The threshold may need adjusting, or you may have a bad light sensor. You can verify whether it’s a bad light sensor if it still doesn’t work when you plug it into the input for Light Sensor 2.
• Similarly for audio and microphone, make sure that the thresholds are set adequately. If StimTracker does not flash the Audio “L” or “R”, or the “Mic” LEDs, then it is not detecting any input.
• The “Resp.” LED should light up when you press a key on the response pad. If it doesn’t, you might have a bad cable.
• For event markers sent via USB, look at the Code “A” and “B” LEDs on StimTracker’s front panel. If neither one lights up when you try to send a pulse, this indicates that StimTracker is not receiving a proper command to generate output. The problem is on the software end on the computer; this is likelier to happen with custom software using C++, Matlab, or Python.

On the output side, when using an m-pod:

• The right rectangular LED (🁢) should be lit, indicating a good connection to StimTracker.
• Look at the event marker indicator (▲) on m-pod itself; it should light up when StimTracker generates an event marker. If it does, then m-pod is delivering the TTL pulse as expected; double-check that your recording software (e.g. EEG) on the receiving end is setup correctly. If the event marker indicator does not light up, then it might be suppressed due to signal mapping in m-pod; see Configuring Pin Assignments.

The Quad model offers a “TTL Output” connector. Typically, using this connector requires a custom-built cable. If you are not obtaining output on this connector, it could be a bad cable, a mis-wired one, or your recording software (e.g. EEG) on the receiving end is not setup correctly.

4. On my Quad, the Mic LED does not light up when I speak into the microphone.

The Mic input on the back of StimTracker Quad can be set as either Mic input or Light Sensor 4 input. If, when trying to adjust the threshold for the microphone, StimTracker Quad displays OFF, turn the knob in either direction and it will display the threshold’s numeric value instead.

5. The m-pod LED is flashing.

When the m-pod LED flashes slowly on StimTracker’s front panel, this indicates that your m-pod’s firmware needs to be updated; see Updating m-pod’s Firmware.

When the m-pod LED is flashing rapidly (2-3 times/second), it usually indicates that a firmware update was interrupted. Turning StimTracker off and back fixes it.

Back to StimTracker Support main page
Last Revision: May 6, 2025