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Gabriel
Joined: 03 Aug 2009
Posts: 1067
Location: Panama
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| Serial Time Out |
 Posted: Wed Feb 13, 2013 9:17 am |
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Hi All,
I am just about finished with a new SMS remote control "driver" (to be posted shortly on the library) but i am a bit annoyed by the use of "delay_ms()"
Due to the nature of the modems, the time they take to reply varies and its nessesary to wait for the modem to accept and reply to the commands sent ...or else
I need a better way to wait for the modem replys...
Currently i use something like this:
| Code: | printf("AT+CMGD=1\r"); // Send Delete SMS command
While(counter_read==0){} // wait for modem to replay
Delay_ms(1000); // delay long enough for modem response |
where i poll the buffer counter and then have a fix delay after the first character arrives... this approach works fine but id like something cleaner, that adapts to the modem rather than just a fix delay and be done with it...
i was thinking of setting a timer and having it reset on the UART ISR and stop waiting (as in continue with the rest of the code) upon the timers overflow...
so instead of having a 1 second (completly arbitrary) fixed delay i would end up waiting whatever the overflow period is on the timer only, after the last char arrives...
i was doing my "homework" prior to writing this post and found this:
| Quote: | | #use rs232(UART1,baud=9600,timeout=500) //timeout = 500 milliseconds, 1/2 second |
as suggested by Temtronic...
suggestions? snippets? i welcome your experiences!
thanks,
G.
_________________
CCS PCM 5.078 & CCS PCH 5.093 |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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Gabriel
Joined: 03 Aug 2009
Posts: 1067
Location: Panama
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| Posted: Wed Feb 13, 2013 11:03 am |
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asmboy,
Thank you for your reply.
you might not remember but you already provided me with your delay function previously... It was a thread on changing baud rates.
It is indeed a very versatile delay function.
i might not have explained my self properly.... or didnt understand what you where trying to say... probably the latter
My problems is not with delay_ms() or with setting a proper time out period.
what i would like is something like:
"wait for one character to arrive at UART and continue executing code after 50ms of no chars being received on UART"...
Something like:
| Code: | While(counter_read==0){} // wait for first char
set_timer0(0); // start timer
While (!overflow_flag) // wait for flag to be set in TMR0 ISR
.
.
. code continues |
and then have in my Serial ISR:
| Code: | #INT_RDA
void serial_isr
{
circle buffer stuff...
set_timer0(0); // Reset timer
} |
| Code: | #INT_TMR0
void Timer0_isr
{
overflow_flag=1;
} |
... i have it figured out i think... i just want your input and experiences on doing something like this...
Thanks
G.
_________________
CCS PCM 5.078 & CCS PCH 5.093 |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Wed Feb 13, 2013 12:42 pm |
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you can use the function i offered by putting a kbhit(stream);
check in the inner loop "polling location" of the function or adapting it to
be part of your receiver function , as the defined poll location lets you do
any check or other fast acting code snippet on a looping basis - as opposed to the dead-time , thumb twiddling of delay_ms();
BTW i never use fixed delays of other than cycles or usecs in CCS code- its always a counter/timer based function similar to the post ,
as much of what i do is for medical/research instruments- and there is
usually a watchdog barking over my shoulder  |
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