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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Dztasheet won’t be able to use your common ground switch arrangement but all other potential problems will be solved. It sounds as though you need a proper keyboard matrix controller. There are other ways that eatasheet many diodes. Load from the switches into the shift register all 16 switches attached to 16 pullups, then step feed the word back to the micro.

There’s no asynchronous load function, like the load function on the 74LS This two-key roll-over is provided between any two switches. Anyone want to make some money via online consulting?

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

Pressing SW4 pulls down IN2. 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.


Serial in parallel out 74LS Pull-ups are required, may be internal dagasheet micro or not. You even get to be able to detect SW0 thanks to the Data Available signal! How do I make each button activate its corresponding address. I think I like the latter best since you can grab the complete switch status at one moment in time.

Feed one output low through the shift register and read back the status on the common line.

To change any data in the shift register at all, the clock must have a falling edge. Pressing SW2 pulls down IN1 only. 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.

You need to modify your question to clarify that you want to prevent two button pressed simultaneously giving an erroneous code. In that case you would need some datasheer of keypad scanner. I’ve just acquired two 74LSs and need help understanding the datasheet.

74LS (Big) bit serial-in serial-out shift register

By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies. A simple solution is to connect a diode from each input to every switch that should pull that input low. If you use more than one of these ICs together with their outputs tied to the same input, you’ll need to manage the CS pins in order to ensure that both ICs don’t try to deliver data at the same time.


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. Sign up using Facebook. Do I gather that you also want to be able to somehow recognize N-key press events? Eduardo Cardoso 1 Pressing SW1 pulls down IN0 only.

(PDF) 74LS Datasheet PDF Download – BIT SHIFT REGISTERS

He just wants to “send a ground” to the input signals. Available output returns to a low level when the entered key is released – even if another is depressed. That looks like Trevor’s “Visio-Lab”.

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. That’s what diodes are for. There’s no single pin that performs a “latch” function. Add pullup resistors if necessary. That is an entirely different proposition.