Unable to configure TIMEPULSE pinout correctly

Q&A forumCategory: QuestionsUnable to configure TIMEPULSE pinout correctly
hrk1996 asked 2 weeks ago

I am attempting to read the TIMEPULSE of 100 ms (ON) and 900 ms (OFF) of the Ardusimple. I set the configurations on U center according to the ZED F9P integration manual, that is setting both the measurement rate (CFG-RATE-MEAS) and the time pulse frequency (CFG-TP-*) to 1Hz. However, when using PPS tools in Raspberry Pi to obtain the PPS information, I do not get any PPS signals, though I get them while using another GNSS receiver’s PPS pin. Also, when connecting the Ardusimple to a micro-controller digital input to see the obtained timepulse, no value is detected. On an Oscilloscope, the output wave from the Timepulse pin gives a very noisy wave. Any suggestions?  

Ardusimple Staff replied 2 weeks ago

Hi hrk1996, the default timepulse configuration is already 100ms ON, 900ms OFF, no need to change any configuration.
The LED “GPS FIX” is driven by this signal.
Can you confirm that by returning the system to default using UBX-CFG-CFG message you still have this behavior? Note that the signal is referenced to 3.3V.

hrk1996 replied 2 weeks ago

Hi, I was getting the ON and OFF states when using a logic analyzer, but it is only 0.6V maximum voltage in the ON state. Because of this, I thought it was just noise when using the oscilloscope. I have used Power + GPS (J1) plug to power the board, and the Timepulse pin 1 along with the ground pin next to the 5V_in pin. Is there anything wrong with my setup?

2 Answers
hrk1996 answered 2 weeks ago

Hi, I was getting the ON and OFF states when using a logic analyzer, but it is only 0.6V maximum voltage in the ON state. Because of this, I thought it was just noise when using the oscilloscope. I have used Power + GPS (J1) plug to power the board, and the Timepulse pin 1 along with the ground pin next to the 5V_in pin. Is there anything wrong with my setup?

Ardusimple Staff answered 2 weeks ago

HI hrk1996, I confirm it’s a limitation of the board that the timepulse works with +0.7V reference, instead of 3.3V as I mentioned above. Nevertheless the pulse should be very clean and easy to read. Hope you can continue your project with this limitation.

hrk1996 replied 2 weeks ago

Do you plan to correct this limitation of 0.7V to 3.3V in future releases? Asking since this will not be sufficient for my application and I will have to step it up.

Ardusimple Staff replied 2 weeks ago

Yes, will be corrected soon. We leave this question open and will inform you once it’s solved.