Open you data sheet and consider the “DC Electrical Specifications” table. How you control those control pins is of course up to you – either with some digital logic circuit for your application or as mentioned earlier with a microcontroller.Īpart from the power supply requirements, there are a few limitations to keep in mind. For example, to select pin 9 (9 in binary is 1001) you set the IC pins S0 and S3 to HIGH, and S1 and S2 to LOW. If you scroll down a bit hopefully you noticed that the combination of S0~S3 is in fact the binary equivalent of the pin number – with the least significant bit first. nothing) it shows what combination of HIGH and LOW for the control pins are required to select which I/O pin the current will flow through. Not only does it show what happens when pin 15 is set to HIGH (i.e. So how does that work? Once again – reach for the the data sheet and review the following table: By setting these HIGH or LOW (Vcc or GND) you can control which I/O pins the current flow is directed through. Finally there are the four control pins – labelled S0~S3. The sixteen inputs/outputs are labelled I0~I15. This is where the current either flows in to be sent to one of the sixteen outputs – or where the current flows out from one of the sixteen inputs. You can always control this with a digital output pin if required, or just tie it to GND if this doesn’t matter. Pin 15 is used to turn the control the current flow through the inputs/outputs – if this is connected to Vcc the IC stops flow, and when connected to GND it allows flow. The power supply for the part is applied to pin 24, and GND to … pin 12. Next – consider the pinout diagram from the data sheet: If for some reason you have the 74 HCT4067 it can only work on 4.5~5.5V DC. The first thing to note is that the 74HC4067 can operate on voltages between 2 and 6V DC, which allows use with 3.3V and 5V microcontrollers and boards such as Arduino and Raspberry Pi. Another way to think abou it is that you can consider the 74HC4067 to be a digital replacement to those rotary switches that allow you to select one of sixteen positions.ĭon’t let that put you off, it’s just what we had in stock at the time. The part itself is available in through-hole and surface mount versions.Īt this point you should download the data sheet, as we refer to it through the course of the article. That’s a mouthful – however in simple form it’s an IC that can direct a flow of current in either direction from one pin to any one of sixteen pins. One example of this is the 74HC4067 16-channel analog multiplexer demultiplexer. It’s a simple binary code, but by chance, you’re one of the 99.8% of people in the world who don’t know binary, here’s a simple table on the right.Now and again there’s a need to expand the I/O capabilities of your chosen microcontroller, and instead of upgrading you can often use external parts to help solve the problem. Thus, transferring all 4 LOW contacts switches CD74HC4067 to channel 0 (thus SIG and C0 will be connected), transferring all HIGH switches to 15 (so SIG and C15 will be connected). 4 digital contacts are used to set HIGH or LOW to binary (0-15) to determine which contact the “SIG” is connected to. In this tutorial, we are just going to read the values of 16 pots, because buying 16 analog sensors for this would be superfluous.Ī multiplexer of this kind actually simply acts as a 16 to 1 switch. It can actually be used in any direction, as well as with serial or other digital interfaces. This allows you to use 4 digital contacts to control the transfer of one contact to 16 others. It is available in a DIP package ready for the layout board, or if you are as dependent on the board as I am, robu.in offers an SSOP version. An analog / digital multiplexer, such as the CD74HC4067 (reduction multiplexer), can help increase the number of contacts you have, and it’s insanely easy to connect to your Arduino or another microcontrollerĬD74HC4067 is a 16-channel analog multiplexer / demultiplexer. Have you ever had enough contacts to read a set of analog sensors? Don’t worry, you are not alone, it happens to the best of us, and you can do something about it.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |