EP 014 – LC7132 / LC7137 PLL Mod with Arduino – Part 1 [CB]
This is still untested in the actual radio, but i see no reason why it shouldnt work. So lets take a look, so were looking at data sheet for the lc 7136 and if we scroll down, we see the truth table for the inputs from the channel select now i know theres different methods of actually piggybacking the lc7132 onto the 7137 and using the Back of the channel display for the inputs to the 7132 because they are different, but it got me thinking that the channel change still outputs a code, a. Why not get an arduino to interpret this code and take the input from the channel select and output it to the correct outputs that the understands? So, if we look at the 7137, we have six inputs and they all change depending on which channel well. Look at the data sheet for the seven one three two and we have eight inputs that is required to identify the channel. Now, as i said, it got me thinking why cant we use an arduino for this, so i set about making a prototype board on a piece of breadboard with some leds and an arduino nano just to see whether, theoretically it could be possible – and this is what Ive come up with so lets. Take a look at the arduino code, so weve set up a few variables. No problem set the inputs, the pin inputs, those are from the channel change because they should be the same in every radio, because every radio uses a 7137 of that type.
So that should be exactly the same, so we set the outputs, the pin mode outputs so were using the analog inputs on the arduino for the input and were using the digital outputs for the out and well just set, pin mode in pin mode out. So thats set up so in the loop weve set digital read on the inputs, and then this is just repeated 40 times so for channel 1. If input state 1 is 1 and then 2 zero, three zero, four zero. Five, zero six is zero, which corresponds to channel one of the um lc. So one three seven and the output should be one one, one, one zero one, one which will look at the code, one one, one zero one one, and then this is just repeated forty times for each one of the different channels, a little bit tedious to write. But once its done its done so once ive done that, i had built it onto a piece of breadboard, and this is what happened on the breadboard. So heres. A quick demonstration of it inputting on the analog inputs. And when you change the inputs on the analog inputs, it changes on the eight led outputs. So in theory this should work. Ive got no reason to suspect it wont because the lc chips will take 5 volts. I hope ive got no reason to suspect they wont um. Some pull up, pull down, resistors there just to stop the arduino going a bit mad, so the next step is to fit it into a radio and see if it works anyway.