UART vs software RS232

[Bruce]

I always use a wait modifier to synch to the first byte in a packet.

This is the line used to receive in my remote sprinkler controller using a pair of
XStream 900MHz OEM modules;

SERIN2 RX,84,[WAIT("A"),CMD,RlyNum,State]

It waits for the A then grabs data. Really simple and it works.

I would probably have used a pair of Linx LR series like Earltyso did, but I built
the remote sprinkler controller LONG before the LR series were available.

[Michael]

Ok -- I'll keep playing with it.

I remember now why I didn't have a wait in there....because I have to keep things moving for counters and other processes....I never tried the wait command but it probably won't hurt anything....few milliseconds at most I guess.

It just keeps ticking me off though because it works prefectly wired, so I hate to be screwing with the code.

Thanks for the input.

[mackrackit]

A wait with a time-out is what you need. After the time-out the code will jump to the label of you choice.

[Michael]

I'm out to lunch on how to use wait and timeout.

here's my code for the receiver.....


SERIN PORTA.4, T1200, [QUAL1, QUAL2], LOWER, HIGHER

Works fine...looks for 2 qualifier bytes...then shows the data (lower and higher).

Do I even need wait? Is it in there as default because I have the qualifiers?

Also, in my PBP book it only talks about "WAIT" in the SERIN2 page ?


If I'm doing something wrong, how would I write the line above using "wait"?

I tried some things but got errors --

[WAIT, QUAL1,QUAL2], ETC
[WAIT,"QUAL1","QUAL2"] ETC

THANKS AGAIN

[mackrackit]

That is how you WAIT using SERIN
From the manual:

‘ Wait until the character “A” is received
serially on Pin1 and put next character into B0
SERIN 1,N2400,[“A”],B0

You are waiting on
[QUAL1, QUAL2]

Now to use a time out, again from the manual

SERIN
Pin,Mode,{Timeout,Label,}{[Qual...],}{Item...}

See what we can do here

SERIN PORTA.4, T1200, [QUAL1, QUAL2], LOWER, HIGHER

change to this to wait on two QUALs and if QUALs are not received in 100ms, then it jumps to "LABELofCHOICE"

SERIN PORTA.4, T1200,100,LABELofCHOICE, [QUAL1, QUAL2], LOWER, HIGHER

Me thinks you are looking at this to hard, relax a bit .

[Michael]

You're right -- that's always the case.

In fact, here is the conclusion.....

I "thought" that I had my code at T1200 but it was at N1200.....BUT, I didn't really care anyway because it was my (mis) understanding that as long as BOTH pics were the same, that it didn't mean diddly squat.

After all, it's just inversion isn't it?...and I was using CMOS inverters on my breadboard...so in my mind, I was trying it "both ways". ?

So, anyway, I just changed both sides to T1200 (I know, that was suggested in the first place).....and all is fine.

BUT what am I missing here?

Like I say, when I set up my wired connection, it didn't matter if I used T1200 or N1200....as long as the were both the same.....it worked either way......so, what am I missing here?

What a pisser.

--Michael

[Michael]

Also --

Is there ANYTHING I can do other than changing the code to T1200?

I have some units already out there using N1200 and was hoping to add wireless function to them.

Again, I tried 4011's but no luck.

When I say anything, I mean ANYTHING.

Could I put another PIC in my wireless module and do something there?

[Bruce]

With your wired connection you had full control over both modes so you could just program
both PICs to send/receive in inverted or non-inverted modes.

With the Maxstream units your only option is to program the sending/receiving PICs to use
non-inverted modes - if connected directly to the Maxstream modules.

If you prefer inverted mode, then a simple inverter on both ends should do the trick, but it
has to be fast enough to handle whatever data rate you use without messing with timing.

I would opt for a simple firmware change before adding new hardware though. Just my 2c.

data is data

Data is data, but inverted or non-inverted does matter. Think about about it like this -
suppose you program a PIC to receive data in non-inverted mode. This PIC is the RF
module. Now connect another PIC to it that you've programmed to send & receive in
inverted mode. It doesn't work.

If you reprogram the 1st one to use the same mode, it works. You have control over that.
You don't with the Maxstream unit. So you program controllers on both ends to use the correct
mode, or insert a data inverter.