Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise . 74ls,, 74ls Matched Datasheet Manufacture, PDF . 1, 74ls, BIT SHIFT REGISTERS, Texas Instruments, 74ls pdf. Texas Instruments 74LS Logic – Shift Registers parts available at DigiKey. SN74LSDW Datasheet · SN74LSDW – Texas Instruments ·

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You can use a couple of 74LS encoders as shown in their data sheet. The clock is CLK, pin 2 on the through-hole package shown at the top of page datashest in the datasheet.

Such an arrangement is called a “diode matrix”. Parallel in serial out 74LS Sign up using Email and Password. The most direct way to do it is to build a diode matrix: That looks like Trevor’s “Visio-Lab”.

74LS673 (Big) 16-bit serial-in serial-out shift register

Another alternative is to turn your buttons into a rudimentary digital to analog convertor and feed that analog value into whatever analog to digital convertor you may have available. Anyone want to make some money via online consulting? A simple solution is to connect a diode from each input to every switch that should pull that input low. A simple diode arrangement to encode the buttons. How do I make each button activate its corresponding address. This is an area where a microcontroller excels – scanning a keyboard matrix in your case 4×4.


I’ve searched the forums and it doesn’t look like anyone has asked this yet. Sign up using Facebook. The Data Available will return high to indicate acceptance of the new key after a normal debounce period. In that case you would need some form of keypad scanner. FYI, The most useful functions: Serial in parallel out 74LS It sounds as though you need a proper keyboard matrix controller. Since it’s only 744ls673 switches, another way this can be done is to use a shift register rather than datwsheet array.

Has anyone used this particular shift register before? There are also purpose built chips that scan the buttons connected as an array like the 74C Add pullup resistors if necessary.

74LS Datasheet catalog

To change any data in the shift register at all, the clock must have a falling edge. Furthermore, a scanned switch matrix is dwtasheet to de-bounce. Pressing SW2 pulls down IN1 only. Home Questions Tags Users Unanswered. Post as a guest Name.


There’s no single pin that performs a “latch” function. How to make a button activate its corresponding binary address Ask Question. But it’s better to show them here for completeness, remember next person searching the web and finding this question may have a different micro or idea in his head. There are other ways that use many diodes.


Pull-ups are required, may be internal to micro or not. I have 15 output buttons and datsaheet digital inputs. Though having 16 buttons using that method would be pushing that technique a tad. That is an entirely different proposition. With all of these you would need to handle debounce in code.

You forgot the pull-ups though. Do Satasheet gather that you also want to be able to somehow datasheeet N-key press events?

I’ve just acquired two 74LSs and need help understanding the datasheet. P1 through P15 are inputs for parallel-loading the shift register. Yes, I finally have a reason to use the “diagonal diode” symbol in CircuitLab. I’ll take it from there. Perhaps a fritzing diagram and a simple sketch lighting 16 LEDs? Pressing SW4 pulls down IN2. There are also purpose built chips that scan the buttons connected as an array like the 74C Or if you have the ability to program one, a small ROM or FPGA can do it.

I’m assuming the inputs are already pulled high by some means. If the voltage is negative, then reverse the direction of the diodes. You need to modify your question to clarify that you want to prevent two button pressed simultaneously giving an erroneous code.