Looking for help with choosing a Logic Level Shifter

Hi All,

I have the following String Pot, Encoder which from what I can tell outputs a 5v SDI-12 signal.

https://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=SE1&DocType=Data%20Sheet&DocLang=English&DocFormat=pdf&PartCntxt=CAT-CAPS0071

I am trying to read the signal using a Campbell Scientific CR350 (link below), however the CR350 only accepts 3.3v input logic.

As a result I am hoping to shift the 5v output signal of the encoder down to 3.3v so I can read it with the CR350. I’ve been looking at the level shifters and see and see a lot that mention shifting for I2C, but want to make sure I can find the right one for the SDI output I am getting from my environmental sensor.

Any help would be appreciated.

Thanks All!

Hi All,

One thing I forgot to mention. I do not care about knowing the clockwise or counter clockwise turning of the encoder, all I care to know is the position of the encoder’s string. As a result, I am planning on only using one of the output wires to simplify the system down to 3 (power, ground, and signal), rather than 4 wires (power, ground, and two signals)

The CR350 takes TTL directly, good to go there.

And has much more tolerant inputs than a micro, anyhow:

I found a few references to quadrature functions while finding these links so it seems like it might integrate even easier than most, nifty instrument.

Edit to add

If you must have 3.3 volts, you have a few easy options.

1- Voltage divider made with 2 resistors. (2 resistors per channel, 4 total.) This is cheap and easy but depending on how fast the pulses come from your encoder it might be too slow.

2- A 74HC4050 DIP IC. Just power the IC with 3.3 volts and apply your 5 volt inputs and it will convert them to 3.3 volt outputs. These are fast enough to handle SPI data and should be able to keep up with an encoder no problem.