synchronization problem

[jijita]

i'm sending data serially from pic 16f84 to 16f877 and then displaying it on leds
the data is encoded
the data ain't arriving to the leds
i used a push button for the first bit sent it just worked for the first
i have a problem of synchronisation that i tried to solve uselessly
any idea

 

[Nigel Goodwin]

i'm sending data serially from pic 16f84 to 16f877 and then displaying it on leds
the data is encoded
the data ain't arriving to the leds
i used a push button for the first bit sent it just worked for the first
i have a problem of synchronisation that i tried to solve uselessly
any idea

Consult my RS232 tutorials, it's very simple to do RS232 between two PIC's.

 

[jijita]

can you please be more precise

please just give me a summary
or a hint on how to start and what i should do basically
it's very important to me
i've been trying without using rs232 to make the code work but in vain
i tried to make the first pic 16f84 wait until the second is ready to receive from it but it worked for the start bits only

 

[Nigel Goodwin]

Re: can you please be more precise

please just give me a summary
or a hint on how to start and what i should do basically
it's very important to me
i've been trying without using rs232 to make the code work but in vain
i tried to make the first pic 16f84 wait until the second is ready to receive from it but it worked for the start bits only

Read the tutorial - it explains everything you need to know, including how it works, and gives proven tested code examples.

 

[jijita]

i want to use only one wire to connect a port of the first pic to the port of the second
i'm doing this to make it wireless later
does that apply to rs232 or i 'm obligated to use connectors

 

[jijita]

i forgot to tell you that i don't want to use a stop bit
i only use a start code (composed of many bits)
i want to test it first on one byte
then on several bytes

 

[Nigel Goodwin]

i want to use only one wire to connect a port of the first pic to the port of the second
i'm doing this to make it wireless later
does that apply to rs232 or i 'm obligated to use connectors

RS232 does only use one wire (for one way), plus the ground wire of course. You can simply connect two PIC's together with out using a MAX232, just join the grounds and connect the TX pin to the RX pin.

For your other point, no stop bit, this makes life rather more complicated, a stop bit is extremely important the way RS232 works - even if you don't bother reading it, which my tutorial code doesn't.

Your mention of wanting to make it wireless later gives the reason, you really need a different system than RS232 for a radio link. I suggest you try searching for "manchester coding", which is a commonly used radio protocol - but be warned, it's a great deal more complicated than RS232, and a lot slower.

If speed isn't important, the Sony SIRC code in my IR tutorial could be adapted for a radio link quite easily.

 

[jijita]

if i'm sure that the code i'm using is synchronising well
could the problem be wire related
i'm using a regular wire i think it's called telephone wire you know the one used when connecting for ex a led to a pin or resistance or whatever
can this wire be causing data loss and if it's true what kind of wire i should use

 

[Nigel Goodwin]

if i'm sure that the code i'm using is synchronising well
could the problem be wire related
i'm using a regular wire i think it's called telephone wire you know the one used when connecting for ex a led to a pin or resistance or whatever
can this wire be causing data loss and if it's true what kind of wire i should use

How long is your wire?, if it's a huge length you could try checking the far end with a scope (if you have access to one).

You could also try using my RS232 code, and see if that works down your wire - that would prove if the fault lies in your code, or in your hardware somewhere (including the wire).