pin state into byte variable - serial...

FORD

Hi All,
Am just wondering if I am going about this the right way, in SXBasic.
I have serial data coming into an SX pin, and want to shift that data into a byte variable.
I'm just not sure if its working correctly...

string is a byte variable.
RA.0 is the serial input pin

immediately after I detect the start bit it goes something like this...

· pauseus 417················ 'align the first data bit to the middle of the bit, correct for 1200bps
· startbit = RA.0············· 'get start bit
· pauseus·833················ 'pause 1 bit period
for counter = 0 to 7········ 'loop for 8 bits of data
· string.7 = RA.0············· 'get the serial input pin state and put it into bit 7 of 'string' variable
· string = string SHR 1····· 'shift bits right
· pauseus 833················
next
··parity = RA.0··············· 'get parity bit
· pauseus 833
· stopbit = RA.0············· 'get stop bit
· pauseus 833

Is there a problem with getting a pin state into a variable this way ?
I mean can you just put any bit of a byte variable directly onto a pin ?

I cant use the serin command, because its E81 comms.


Cheers,
Chris, Weastern Australia.

Bean

That looks okay, except that you should shift the byte BEFORE storing the new bit.

for counter = 0 to 7
· string = string SHR 1
· string.7 = RA.0
· pauseus 833
next

Bean.

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FORD

Thanks Bean,

yes, otherwise i shift bit 0 out of the byte on the last rotation.

So does this look ok for sending a byte...

string var byte

for counter = 0 to 7
·RA.0 = counter.0
·string = string SHR 1
·pauseus 833
next

I'm just not sure about putting bits onto pins, if it needs to be done from a bit or byte variable etc...

Cheers, Chris

JonnyMac

Chris,

I've attached a demo that works. Note that I had to disable collecting the parity bit as my terminal program can't send it. Also, you don't have to collect the stop bit -- use that time to do something with the data you've just collected from the serial input.

Jon

FORD

Thanks Jon, appreciated...

Is there a dedicated manual for SXB programming around for sale or download ?

Cheers, Chris, West Oz.

JonnyMac

There is an online SX/B help file -- it's in the SX-Key IDE. Make sure you've got the latest IDE and compiler. There are at least two of us that are presently writing books on SX/B.