PING Revisions: Rev A vs Rev B vs Rev C

Ron Czapala

Does anyone know what the differences are between the different versions?

I have Rev A and Rev B sensors but noticed that Rev C is the current version.

Publison

Ron,

Post #47 shows the difference in a photo, but not the schematic:

http://forums.parallax.com/showthread.php/136921-Scribbler-S2-amp-Ping-question.

Never seen a Rev C yet.

Jim

EDIT looks like REV C went to a 16.Mhz resonator? (Per picture on the Parallax web site.)

Publison

From the product page:

Rev A: original release
Rev B: resonator added to the SX-28 co-processor circuit. No changes to functionality
Rev C: SX-28 co-processor changed to PIC16F57. No changes to functionality.

Ron Czapala

Publison wrote: »

From the product page:

Thanks! I didn't spot that. I wondered whether any of the changes affected performance or needed different code (timing, etc)

Phil Pilgrim (PhiPi)

I think the addition of a resonator made the biggest difference, since the transducers have an extremely high Q, and accurate 40 kHz frequency generation is a must. The switch from SX to PIC probably has no significance re: performance. As far as echo timing goes, the presence or absence of a resonator makes no difference whatsoever, since the pulse width is the actual unprocessed echo time.

-Phil

Chris Savage

Rev. A used the internal oscillator for timing. Rev. B added a 4 MHz resonator to improve timing accuracy across temperature range, as Phil mentioned. Rev. C was a change from the SX28 (which is EOL) to PIC, which requires a 16 MHz resonator to have the same timing.

Ron Czapala

Phil Pilgrim (PhiPi) wrote: »

I think the addition of a resonator made the biggest difference, since the transducers have an extremely high Q, and accurate 40 kHz frequency generation is a must. The switch from SX to PIC probably has no significance re: performance. As far as echo timing goes, the presence or absence of a resonator makes no difference whatsoever, since the pulse width is the actual unprocessed echo time.

-Phil

Chris Savage wrote: »

Rev. A used the internal oscillator for timing. Rev. B added a 4 MHz resonator to improve timing accuracy across temperature range, as Phil mentioned. Rev. C was a change from the SX28 (which is EOL) to PIC, which requires a 16 MHz resonator to have the same timing.

Phil and Chris
Thanks for the explanation - makes sense now!

- Ron