Bi-Directional Logic Level Connector HV not reading LV pulses

[rtwsocks]

Hello,

I am using the SparkFun bi-directional logic level converter to communicate between a PSoC microcontroller and a 12V water sampler. The sampler will pump water after 12V pulses have been sent to it, and return 12V pulses indicating the sample number and when it is taking the sample. The PSoC microcontroller will only receive and send 3V pulses, but the sampler will only be triggered with a 12V pulse. The logic level converter is being used from the microcontroller to the sampler and from the sampler to the microcontroller. When the wires to the logic level converter are connected and grounded, the HV side of the board is not receiving the pulses from the LV side of the board. When the PSoC microcontroller is in sleep mode and not sending any pulses, the LV side has a low voltage on pins that should not be receiving any voltage and the HV side has pins with a higher voltage that should not have any voltage readings. I have attached an image of the voltages read from a multimeter when the only pins that should have voltage are LV:3.5V and HV:12.4V.

Any insight would be appreciated.

[YellowDog]

OK, so you have three lines that get connected between your micro controller and your 12 volt device.

What are they?

Does each one send data in both directions or only one?

I’ve never heard of 12 volt logic before, are these logic or something else? (contact closure, open collector, etc)

Is there a link to a manual for the 12 volt device you can share?

[rtwsocks]

The logic converter we are using is this one: https://www.sparkfun.com/products/12009

It is only rated up to 5V on the HV side, but I have seen in other forum posts that they have had success with it from 3V to 12V. I included the directions of current in this new version of the diagram. The yellow arrow sends 20 ~50ms pulses from the microcontroller to the sampler, and the HV side is just listening for the pulses at 12V. The blue and green arrows are sending pulses from the sampler to indicate when the sampling occurs and a number of pulses indicating the sample number, respectively. None of the pins should be switching direction when used, and the grounds have been connected.