Time-Nuts, Thanks for your interest in checking out the PICTIC II and working together to simplify ordering the boards and parts. My hope is by making the code available others will find ways to improve on the basic design and will share their modifications to make this a better project. As Stanley and Bob have mentioned the baud rate can be modified in the code and I have had good success at serial rates up to 57.6K even though the internal PIC 8M osc is used. Many users will want to use an external timebase so 10M was selected as the default, but the timebase rate can be increased for greater resolution with appropriate selection of the sample capacitor values and XO rate during construction as desired. The board was designed so either a half or full can XO can be used and for top adjust trimmers with either staggered or in-line center pins for flexibility. The PICTIC II was a spin-off of a 1ns front-end for a GPSDO controller and is not intended to replace a good commercial time interval counter. But it is a simple TIC that could be useful in many amateur applications. The accuracy will depend on the timebase and interpolation gain used, with faster timebase rates and lower interpolation gains increasing the accuracy. Since commercial TIC designs use a fixed gain and the PICTIC II interpolation gain is variable, you can decide the best compromize between resolution and accuracy for your application. This flexibility makes it difficult to publish any meaningful specifications for the PICTIC II other than to say the interpolators with both doubler stages installed will provide a hardware gain of 800 when properly adjusted. The software gain can then be reduced to say 100 so an 8 count variation in the interpolation hardware is reduced to a single count variance in the combined 1ns TIC data for improved accuracy.
Richard > Looking at Richard's code in PICTICII.ASM : > > bsf TXSTA,BRGH ;set USART hi speed mode > movlw D'51' ;set async rate at 9600 baud (51. for 8 > MHz int, BRGH=1) > movwf SPBRG > > Then '25' would be 19,200 baud > and '12' would be 38,400 baud > > Need to test this but could be a way to get more data out. > > Stanley > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
