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POProgramming a ripple counter in C with JK flip flops
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2013-12-26T04:25:14.893
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I've decided to have a go at programming flip flops in C. I've had an attempt at both a D and JK flip flop (without preset and clear sections yet). I'm testing if by cascading them, I can get them to produce a simple 4 bit ripple counter. After writing my code and running it, it seems to produce some really weird results in the form of: Clk: 01010101010101010101 OuA: 01100110011001100110 OuB: 01000100010001000100 OuC: 01111000011110000111 OuD: 01010000010100000101 Where Clk is the input clock, OuA is output A, OuB, output B etc. As you can see, OuA and OuC seem somewhat acceptable with the ratio of on to off but B and D seem really odd! My code is: <pre><code>#include <stdio.h> #include <stdlib.h> void DFF(int Clk, int D, int *Q, int *NQ) { if(Clk) { *Q = D; *NQ = !*Q; } } void JKF(int Clk, int J, int K, int *Q, int *NQ) { if(Clk&J&(!K)) { *Q = 1; *NQ = 0; } if(Clk&K&(!J)) { *Q = 0; *NQ = 1; } if(Clk&J&K) { *Q = *NQ; *NQ = !*Q; } } int main() { FILE *fptr; const int Len = 20; int Clk = 1, ClkA[Len]; int n, OA[Len], OB[Len], OC[Len], OD[Len]; int Q = 0, NQ = 1; int Q2 = 0, NQ2 = 1; int Q3 = 0, NQ3 = 1; int Q4 = 0, NQ4 = 1; for(n=0; n<Len; n++) { Clk^=1; JKF(Clk, 1, 1, &Q, &NQ); JKF(Q, 1, 1, &Q2, &NQ2); JKF(Q2, 1, 1, &Q3, &NQ3); JKF(Q3, 1, 1, &Q4, &NQ4); ClkA[n] = Clk; OA[n] = Q; OB[n] = Q2; OC[n] = Q3; OD[n] = Q4; } fptr = fopen("c:/ff.txt", "w"); fprintf(fptr, "Clk: "); for(n = 0; n<Len; n++) fprintf(fptr, "%d", ClkA[n]); fprintf(fptr, "\nOuA: "); for(n = 0; n<Len; n++) fprintf(fptr, "%d", OA[n]); fprintf(fptr, "\nOuB: "); for(n = 0; n<Len; n++) fprintf(fptr, "%d", OB[n]); fprintf(fptr, "\nOuC: "); for(n = 0; n<Len; n++) fprintf(fptr, "%d", OC[n]); fprintf(fptr, "\nOuD: "); for(n = 0; n<Len; n++) fprintf(fptr, "%d", OD[n]); fclose(fptr); return 0; } </code></pre> I apologise about the clarity and I know its probably not particularly efficient but could someone please clear up what is happening with the outputs? Cheers!
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<c><counter><flip><flip-flop>
Title
Programming a ripple counter in C with JK flip flops
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