https://electrosome.com/topic/18f4550-with-74ls138/feed/ Sat, 18 Mar 2023 05:01:20 +0000 https://bbpress.org/?v=2.6.9 en-US https://electrosome.com/topic/18f4550-with-74ls138/#post-11467 https://electrosome.com/topic/18f4550-with-74ls138/#post-11467 Wed, 10 Jun 2015 05:55:23 +0000 ericJ I am trying to connect 127 switches to the microcontroller using three 74ls138  decoders how will I scan the switch for buttons pessed

]]> https://electrosome.com/topic/18f4550-with-74ls138/#post-11471 https://electrosome.com/topic/18f4550-with-74ls138/#post-11471 Thu, 11 Jun 2015 03:00:13 +0000 Ligo George You may use it like matrix keypad. Use 6 pins of PIC as inputs such that you can connect 24 x 6 = 144 switches.

]]> https://electrosome.com/topic/18f4550-with-74ls138/#post-11507 https://electrosome.com/topic/18f4550-with-74ls138/#post-11507 Sat, 20 Jun 2015 04:11:20 +0000 ericJ I used the program in the tutorials on the 4×4 keypad as an example I modified it to scan the rows using the 74LS138 but I can not get it to work properly. I attached the I used. Please let me know what I am doing wrong.

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