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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Add pullup resistors if necessary.
I think I like the latter best since you can grab the complete switch status at one moment in time. Pressing SW4 pulls down IN2. Perhaps a fritzing diagram and a simple sketch lighting 16 LEDs? The MM74C key encoder. Let me try adtasheet That’s what diodes are for. This two-key roll-over is provided between any two switches.
If the voltage is negative, then reverse the direction of the diodes.
74LS pdf Datasheet P1 Part Num IC-ON-LINE
datasheet That looks like Trevor’s “Visio-Lab”. Pressing SW1 pulls down IN0 only. There’s no asynchronous load function, like the load function on the 74LS Yes, my inputs are already pull-up, the problem is that with this type of configuration I can only recognize one key at a time, if I activate keys 1 and 2 at the same time the input will receive 3. You need to define what is to happen when 1 a second key is pressed while the first is held down 2 when the second key is released before the first and 3 when the second key is released after the first.
Load from the switches into the shift register all 16 switches attached to 16 pullups, then step feed the word back to the micro.
74LS673 (Big) 16-bit serial-in serial-out shift register
A simple solution is to connect a 7l4s673 from each input to every switch that should pull that input low. Parallel in serial out 74LS Available output returns to a low level when the entered key is released – even if another is depressed. A simple diode arrangement to encode the buttons. Eduardo Cardoso 1 Such an arrangement is called a “diode matrix”.
(PDF) 74LS673 Datasheet download
I have to do this without one button influencing the other. The most direct way to do it is to build a diode matrix: Since it’s only 15 switches, another way this can be done is to use a shift register rather than an array. However your statement “have to do this without one button influencing the other” and comments imply you need the ability to detect more than one button pressed at the same time.
Sign up or log in Sign up using Google. Note that I’m assuming that 74sl673 inputs rise to a positive voltage if not grounded; i. Home Questions Tags Users Unanswered. 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.
clock, data and latch on the 74LS
The clock is CLK, pin 2 on the through-hole package shown at the top of page 2 in the datasheet. Pull-ups are required, may be internal to micro or not. You are not answering Jonk’s question.