Serial to Parallel using PIC and CCSC

[pete]

Hi!
Can somebody post a code that converts serial data, say 10110010 into parallel that will lit an led corresponding to the serial data? The serial data come into groups of 8bits. Every group of 8 bits, will be displayed in LED in parallel and LED will light by 1 sec on and 1 sec off. For the next group of 8bits serial input, the LED will light again corresponding to the serial inputs. Thanks...

[Guest]

If someone else does this all for you, how are you going to learn about PICs and C programming?
Try and make it work and then post here with what you've tried and what happens if it doesn't work. That way the kind people here will be able to point out your mistakes and your life will be richer for the experience gained.

[pete]

This is a test program. I am sending serial bit 101 using x10 protocol in sending 1 and 0 (without the start code, house code and function code). Program below is for the receiver just to received 101 in parallel to 3 LEDs. This works properly receiving 101. For any other 3 bit binary combinations sent, the LEDs doesn't light correctly. Where could be the problem??


#include <16F628A.h>
#include <STDLIB>
#fuses HS,NOWDT,NOPROTECT
#use delay(clock=10000000)
int hc[6]={0,0,0,0,0,0};
int i=0;

#int_ext
my_interrupt()
{
hc[i]=input(PIN_B1);
i++;
if(i==5)
{

output_bit(PIN_A0, hc[0]); // led 1
output_bit(PIN_A1, hc[3]);// led 2
output_bit(PIN_A2, hc[4]);// led3

i=0;
}

}

void main()
{
output_a(0b00000); // initialize port A



set_tris_b(0b00000011); // set direction registers
set_tris_a(0b00000); // set direction registers

ext_int_edge(L_to_H | H_TO_L);

enable_interrupts(GLOBAL);
enable_interrupts(INT_EXT);


while(true);
}

[Guest]

You appear to be trying to configure the external interrupt for both low-high and high-low edge transitions with:

[mskala]

You cannot use EXT_INT with both rising and falling edges, at least on this part. Also, I don't know why you would need to, you are using 6 transitions to try to store 3 bits. Just pick the active edge and store 3 bits.

Also, even if your both edges routine was working, you light LED's by locations hc[0], hc[3], hc[4]. They would show up in either 0,2,4 or 1,3,5 depending on your protocol.

Also, you are using '#use standard_io' by default by not having a '#use' line stating otherwise, so setting tris_a bits is totally unnecessary after the output_a() command.

[pete]

Thanks for your replies and comments.
I need both positive and negative going edge since I need it to inject the 1ms pulse after each zero crossing of power line. In x10 powerline communications, when you transmit a "1", it is transmitted as "1 0" and for "0" it is transmitted as "0 1". Now this sequences of 1 or 0 is transmitted within 200us after each zero crossing of powerline(I convert it already to square wave for PIC input of zero crossing). Further, the transmiited "1" is represented by 1ms burst of 120khz sine wave. A "0" is represented by no burst. The x10 receiver, demodulates this bursts into TTL level for PIC input.
Now the PIC needs to decode this transmitted bit sequences.

I particularly select those locations of Hc[] since that is my expected times when the sequence 101 can appear in the receiver.

How could then I trigger an input pin RB0 to respond to both positive going and negative going edge of the input?

Is there a limit in CCSC compiler speed to capture this pulses at correct timing that may warrant to use assembly language?

[Ttelmah]

To detect both edges, you need a different approach. Either an external zero-crossing detecotr, whic generates a pulse to feed the interrupt, or use one of the high four bits on port B, and the 'interrupt on change' feature. realistically, you need to be using external signal conditioning, whichever approach is used, since the 'logic' transitions, will occur at different points on the falling and rising edges of an AC waveform, and will not give good detection of the crossover point.

Best Wishes