How to Serial comm. wait for a string?

[Art]

Because you are typing, there will always be an enter character to terminate the string,
so you only need to fill a buffer, and check each byte for the enter character,
then you have all the time in the world for the program to look at the string
rather than trying to figure out what is going on in-between each byte being sent.

Same with GPS, I prefer to fill a buffer with the entire command, and count two bytes after the * char is received,
then look into the content after the entire sentence is received.

[flotulopex]

Hi,

This is the way time can be read "on the fly" from a serial GPS receiver module like this one

GPGGA_Time:
   SERIN2 GPSfrom,GPSbps,[WAIT("$GPGGA,"),STR GPS_D\6]
   LCDOUT $FE,2,GPS_D(0),GPS_D(1),":",GPS_D(2),GPS_D(3),":",GPS_D(4),GPS_D(5)
GOTO MAIN:

The PIC is waiting for the string $GPGGA, from the GPS module to arrive, then it fills an array with the 6 next incoming characters and displays them.

[Art]

Oh my, you’ll have a bunch of unneeded checking when the sentence could have been discarded for no fix or bad checksum.
Some GPS modules also put out a bad but valid time from their battery clocks until a position fix is acquired.
Not good if you were logging for a security system or something like that.

The thread isn’t necessarily about GPS, but it’s more or less the same thing.
You might has well make use of the UART if it’s present.

set a character counter to zero

charbuffer var byte[60]
character var byte
charcount var byte
charcount = 0

receive the serial with hserin with the smallest possible timeout so it will only give you a character if one is present in the buffer

‘pseudocode

hserin [character,lowesttimeout,timeoutlabel]
charbuffer[charcount] = character
charcount = charcount + 1

if character = enter or linefeed, etc. then
gosub investigate’ investigate the complete sentence and reset charcount
endif

timeoutlabel: