7 segment LED, MSP430 and 74HC595.
  8 digits screen (two lines by 4) based on two SN74HC595N. Serial connection to MSP430 (data via 'Data' & 'Clock' lines).

Any questions - e-mail below.
Key - 7LED in subject.

  The previous page, gave you a brief idea of what it is and what parts are needed to accomplish this project. On this page only additional information that would understand how it works (in the hope that someone will try to program such screen on their own). I will program MSP430F2011 only because I have it. You can use any other micro controller you like.

  OK. Below, only that part of the schematic diagram that will interest us at this time.



  74HC595's are 8 triggers connected in series, where the output of the last one comes to pin Q7'. Here you can connect the next 74HC595 ... and so on indefinitely. On schematic, two 74HC595 runs as 16-bit latch.

  Unlike 74HC273, in 74HC595 internal trigger's are connected to real outputs (Q0-Q7) via additional latches, which need to be controlled separately. It's simple. On the positive edge of WRITE signal a data will be copied to output latch


 The simple idea is that we push bits through DATA line and latch each of them with CLOCK signal. To move data from internal latches to external ones, we use WRITE signal.

  The following picture shows the sequence on DATA & CLK lines, in order to reproduce 'c' symbol on the seventh indicator. Of course, shortly after you sent all 16 bits, you have to raise and lower the 'WRITE' signal, so that the digit appears on outputs Q0-Q7.

  As before, the screen's update falls on the shoulders of MSP430. The micro controller does this job nonstop, 512 times per second (each digit is updated 64 tps). To do this simply way, MSP430 runs from 32768 crystal (X1) and the WD timer awakens processor, precisely, each 1/512 sec.
  Voltage regulator (U2) is desirable. The additional voltage divider (R2,R3) receives a signal from the speaker (which is present in any GM counter) and protects the microcontroller's input (P1.0).

 Coding is simple. The positive edge on a 'clock' line writes the status of 'data' line to the first trigger.
The positive edge on a 'write' - overwrite output. One digit is shown at one time.

  --------Here will be a "step by step" code sample for MSP430, but I'm too lazy to do it at this time..---------

  Just like the last time, the coding is simple and does not take much time. Of course, you will do it sooner than I do.

  Most likely, my coding will be on the next page, as this is not a short case.

/*  P.S.My code is already written and working. But he is far from perfect, and is not ready to be shown.
*/



Dec.22,2017  SK_Lab

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