DATASHEET 74LS165 PDF
This device is an 8-bit serial shift register which shifts data in the direction of QA toward QH when clocked. Parallel-in access is made available by eight. Texas Instruments 74LS Counter Shift Registers are available at Mouser Electronics. Mouser offers inventory, pricing, & datasheets for Texas Instruments . 74LS 8-bit Parallel In/serial Output Shift Registers. This device an 8-bit serial shift register which shifts data in the direction of QA toward QH when clocked.
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In this tutorial, I am going to show another shift register which is capable of expanding input pins. One of the advantages that need to be stressed on is that by using only four pins, I can get eight input pins.
Moreover, it can be cascaded, thus you can have any amount of input pins with only four pins with the help of this shift register.
74LS165 Datasheet PDF
The input pins of the shift registers are pin 11 to 14 D0 to D3 and pin 3 to pin 6 D4 to D7. The input voltage acceptable range is between GND to Vcc, where maximum allowable voltage for Vcc is 7V according to the datasheet. However, it is recommended to operate the chip at 5V. After discussing about the input and output pins, let us move on with the control pins.
To control the shift register, you would need three pins which are parallel 74sl165 input PLclock input CP and clock enable input CE.
Another pin that is useful especially when you want to cascade a few shift registers together, which is Serial Data Input DS. Schematic on how to cascade the shift register will be shown later on.
8-Bit Parallel In/Serial Output Shift Registers
Now, let us look into detail how to use the shift register. Initially, you need to make the parallel load input high.
A low signal will triggers the input to be loaded into the shift register. This gives you a flexibility when to read the input to the shift registers. Besides, you want to stop reading the inputs while serially sending the output.
Next, you need to send the clock pulse to the shift register in order to obtain the serial output. However, you would need to set the clock enable before clocking out the data.
After the clock is enabled, the parallel input data will be sent out in eight clock pulses.
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Notice that I am using a pull up datashee of 10k ohm on all the inputs. You can can also change it into pull down resistor network connection. To cascade between two 74HC shift register, all you need to do is to connect the Serial Output Pin 9 of first stage 74lx165 Serial Input Pin 74la165 of the second stage. You can cascade a lot of shift register to get tons of inputs. In order to ease the process of reading data from shift register, I am using an Arduino built in function which is ShiftIn.
Last but not least, a video demo showing the operation of 74HC Shift Register. July 31, at 5: November 27, at 9: 74lz165 nice But, with two 74hc cascade case, how would be the code for this case??
December 1, at 8: Hi J Dacampo, Thanks. If you would like to cascade 74HC, the only modification you need to make is add the number of shiftIn depending on how many you are using. Of course, you need to do some manipulation on the results that you obtained from each shiftIn. November 19, at 2: Hey zxlee, great article, It helped me a lot.
June 11, at Hi Maria, sorry for the late reply. Thanks for the kind words. Recently I just updated the Arduino Piano project, https: You can refer there on how to use two 74HC to increase the number of input pins. May 11, at 7: Why have you dataeheet out the decoupling capacitors? You need a 0.
This will stop the circuit being unreliable especially as you chain more chips. June 27, at datashee Now I know that it is better if we can include a 0. December 16, at 9: As I have given lcd. Fatasheet 17, at Hi Sammy, please refer to the code in the article, line 39 to 51 is how the bits are converted into printable characters on the LCD.
December 19, at 9: Thanks datashert your kind reply… See I have followed you and understood your line 39 to 51 is printable datasheeh.
December 19, at Dear Object means the instrument which is a digital keyboard for music playing and its display lcd is not available and its very much important to me, its my first keyboard therefore I want to get the display data or display screen of the instrument on arduino lcd. December 30, at 4: From my understanding, you have the buttons well connected to the shift register and the output of shift register is also connected to the Arduino. If you are using other display, you may need to change to code for the display.
Another thing that you can try is, datsheet make sure you read what is exactly send from the shift register. Change the code to display it using your serial monitor. From there, if you able to read the correct input from your buttons, datawheet its just the display code you need to work on.
January 8, at 7: January 8, at 8: January 11, at 9: January 11, at If you need to read the inputs to shift register and display it on your HD using Arduino, the code provided above would work for you.
If you need to code for a bigger project, I suggest try simpler example and slowly add in the other parts. You datazheet commenting using your WordPress.
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Notify me of new comments via email. Notify me of new posts via email. Create a free website or blog at WordPress. A summary of the shift register operation is shown is the timing diagram below. ShiftIn data,clock,order — The data is the input pin on Arduino to read the output from shift register whereas the clock is the pin connected to datashewt register clock.
James July 31, at 5: J Dacampo November 27, at 9: Maria November 19, at 2: Leave a Reply Cancel reply Enter your comment here Fill in your details below or click an icon to log in: Email required Address never made public. Build your own Arduino Uno.
74LS Datasheet(PDF) – Fairchild Semiconductor