DT Interrupt and Elapsed Time Running Slow

[ShaneMichael]

OK, HSEROUT is working, and so is the timer interupt. After almost 30 minutes, it was slow about 20 seconds. I'm guessing that could be drift in the internal OSC? It's all I'll need for the current project.

I used the HSEROUT settings from the PBP manual, I compaired them to the data sheet for the 18F2550, I didn't see anything that I felt like I should change. Learned my lesson with the T1CON settings.

Thanks for the help.

For those reading this that are worried about changing from Debug to HSEROUT, it wasn't bad, I used the following Defines:

     DEFINE HSER_RCSTA  90h
     DEFINE HSER_TXSTA  20h
     DEFINE HSER_BAUD   9600 
     DEFINE HSER_CLROERR    1

The HSEROUT looks like this:

Hserout [10," M: ",dec Minutes," S: ",dec Seconds," T: ",dec Ticks,10]

I'm using the "Serial Communicator" in MicroCode Studio (F4 key)

The pic is connected to a MAX232, I think this is needed for HSEROUT? Someone correct me if I'm wrong.

Also I'm using a DYNEX RS232 to USB adapter:

Model: DX-UBDB9 from BestBuy

I'm Using Windows VISTA, so I downloaded the latest drivers from their website, and only had moderate issues with VISTA ( mostly operator error )

Hope this helps out anyone else that has questions about a setup.


Shane

[bogdan]

The HSER_TXSTA should be 20h or 24h ?

[mister_e]

Using the internal OSC sure leads to problems one day or another, even with newer OSC accuracy.

@8MHz and 9600 baud, it shouldn't matter if you use 24, or 20 for TXSTA as both will return the same error %... BUT assuming some ASM limitations, asking PBP macro to calculate the SPBRG value for you, could give some difference at this point.

See what a single digit of difference can do

@8MHz and TXSTA=20,
if SPBRG=11, err% =8.507%
if SPBRG=12, err% =0.16
if SPBRG=13, err% = -6.994%

When TXSTA=24
if SPBRG=50, err% =2.124%
if SPBRG=51, err% =0.16
if SPBRG=52, err% =-1.73%

Play safe and set SPBRG yourself.

DEFINE HSER_RCSTA 90h ' Enable serial port & continuous receive
DEFINE HSER_TXSTA 20h ' Enable transmit, BRGH = 0
DEFINE HSER_SPBRG 12  ' 9600 Baud @ 8MHz, 0.16%
DEFINE HSER_CLROERR 1 ' Clear overflow automatically

This is where I begun to think about some Standalone Calc software. First was E-Z SPBRG Calculator, then it grows and became PicMultiCalc.

Download it
http://www.picbasic.co.uk/forum/atta...7&d=1225550328