3 wire serial interface

This website requires cookies to provide all of its features. For more information on what data is contained in the cookies, please see our Privacy Policy page. To accept cookies from this site, please click the Allow button below. SS or! SPI has separate pins for input and output data, making it full-duplex.

Some chips use a half-duplex interface similar to true SPI, but with a single data line. As an example, we have chosen to work with the National LM74 temperature sensor, whose pinout is shown below:. Something about input throwing it into Slave mode? Has anyone out there written code for this, or a significantly similar, device? I have only been given one example device and am concerned that I might inadvertently overwrite the very data I need to read.

I had figured most of that out from the data sheet all but the shiftIn and shiftOut functions. I was really hoping for some wiring advice. I am not expecting someone to write this for me, I am just looking for something similar I can use as a starting point.

Sort of like this:. The category-5 quad twisted pair shielded cable can extend up to feet without data corruption. It is also necessary to check where the bit output DATA sits in the bit data frame. Figure 1b. The serial interface lends itself to galvanic isolation with external optocouplers.

Figure 2 shows the block diagram of the LTC The internal architecture has been optimized to send out data serially during conversion, without degradation of conversion accuracy due to digital noise.

As a result, the analog accuracy of the LTC is insensitive to the phase, duty cycle or amplitude 3V or 5V of the external digital inputs. The LTC is ideal in multiple-ground systems, where the differential input is connected to one ground, the supplies and grounds of the LTC connect to a second, local ground and the output ground connects to a third, digital ground. A proprietary sampling front end circuit achieves exceptional dynamic performance at the 1.

Figures 3 and 4 show the spectra from a 1. With this very clean spectrum, the LTC minimizes crosstalk and interference in communications applications where the spectrum is divided into many frequency slots.

So how are these two different, and how would I hook them up? Chetan Bhargava 4, 5 5 gold badges 25 25 silver badges 39 39 bronze badges. Add a comment. Active Oldest Votes. I would prefer I2C because speed doesn't matter in this scenario. The ATMega microcontroller has hardware peripherals for both methods so it's up to you. Hardwarefreak Hardwarefreak 1 1 silver badge 3 3 bronze badges. SPI is then much easier to debug because you don't need to deal with a protocol.

First, SS should be connected to ground, not power. Matt Young Matt Young You and Hardwarefreak responded simultaneously, but I found his answer to be a bit more complete. Many thanks again. Chetan Bhargava Chetan Bhargava 4, 5 5 gold badges 25 25 silver badges 39 39 bronze badges. Although you didn't answer my question directly, your answer is an excellent supplement to the above answers. Extremely helpful.

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