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Topic: TTL Confusion (Read 1 time) previous topic - next topic


I'm confused about what exactly TTL means.  I have a Hagisonic AniBat UltraSonic Sensor HG-M40DAI which returns a positive TTL signal indicating that a ping has been received. It causes a ping to be transmitted by sending a signal on one wire and waits for the response on another wire.

My confusion lies in the fact that whenever I search for TTL, I seem to get  items about TTL and RS-232.

So can I just use two of the Ardino's pins to communicate with the sensor?

The  datasheet for the sensor is at:



May 29, 2009, 04:21 pm Last Edit: May 29, 2009, 04:22 pm by Grumpy_Mike Reason: 1
TTL - Transistor Transistor logic.
TTL signals - nominally 0v for logic zero +5V for logic 1.


So can I just use two of the Ardino's pins to communicate with the sensor?



TTL refers to the Transistor-Transistor Logic family.
In the early days, there were also some RTL (Resistor-Transistor) and DTL (Diode-Transistor) logic families.

The TTL logic family was designed for a 5 volt power supply.
A TTL logic zero is anywhere from zero to 0.8 volts, and a logic one is anywhere from to to 5 volts.

The advent of TTL enabled integrated circuit complexity to make a leap from small scale integration (one or two logic gates) to medium scale (a couple dozen gates). This boost in the number of gates per package made TTL very, very popular.

Because of it's early popularity, most succeeding logic families (PMOS, NMOS, CMOS) attempted to be 'TTL Compatible'.

As for whether you can use your Arduinos I/O pins... if you have a 5 volt Arduino then you are in business. If you have a three volt, then you may have to do some voltage level shifting.


Thank you both for your reply. I  did read the article in Wikipedia, but found it to be a bit too complex for me. I've gone back to it and now understand it a bit more.  At any rate I can now use the sensor.

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