Propeller AB Rev A and Rev B with XBee S6B giving different Ping measurements

banjo

If this is not the correct forum, perhaps some moderator can move it. It does relate to the Propeller Activity Boards revisions A and B.

As posted earlier in the Sensors forum (http://forums.parallax.com/showthread.php/159594-Ping-errating-on-Activity-Board-with-USB-and-6V-connected-simultaneously), I have issues when using XBee S6B and the external power supply.

For Christmas I bought a second Activity Bot. It has PAB Revision B and I wanted to compare it to my 2 Rev. A boards.
With revision B the Ping sensor gives same correct results whether the XBee is plugged in or not, while revision A behaves correctly only without XBee.

So my conclusion is that there's a difference between revisions A and B that impacts at least when XBee S6B is plugged in.This is also touched upon in this year old thread http://forums.parallax.com/showthread.php/153072-XBee-Wifi-amp-Propeller-Activity-Board-how-to-connect?p=1233519&viewfull=1#post1233519

Can anyone confirm if my conclusion is correct?


Edit: One rev. A and the rev. B behave correctly while the other rev. A is misbehaving. So might I have a malfunctioning PAB or at least part of it?
I removed all other circuitry and cables from all three boards to ensure comparability between them
It is also emitting a faint but audible high pitched whine with external power connected which the other boards don't. I wouldn't have thought about this if not remembering this recent similar Quickstart post http://forums.parallax.com/showthread.php/159555-Voltage-Regulator-Whine-on-QuickStart-Rev-B?p=1309183&viewfull=1#post1309183
FWIW: The misbehaving rev A is dark blue colored while the well-behaving rev A and rev B are a bit more greenish.

Duane Degn

How are you powering the board? If you're powering it with the USB cable, you may want to try using a good battery pack.

Also which pin are you using to communicate with the Ping? I think all the servo headers have a series resistor on the signal line. If you're adding an additional resistor to the signal line, the extra high resistance may be interfering with the signal.

banjo

I'm powering with a fresh battery pack (tried with both 5 x 1.2 NiMh and 5 x 1.5 AA batteries). I have the Ping breadboarded with a 2 KOhm resistor on the signal line to pin 7, so not using servo headers (although I tried that too in the troubleshooting phase).
I only have issues on PAB Rev. A when using the external battery pack and XBee S6B. An identical setup on PAB Rev. B behaves correctly.

Edit: See additional comments in first post. One rev A is misbehaving while another rev A and a rev B are behaving correctly.

David Carrier

Rev A of the Propeller Activity Board does not support any version of Digi's XBee Wi-Fi modules. Propeller Activity Boards marked Rev B or later support the S6B version of Digi's XBee Wi-Fi module, but not the S6 version. Unsupported modules may work, but there is a significant chance they will lose functionality.

— David Carrier
Parallax Inc.

banjo

David Carrier wrote: »

Rev A of the Propeller Activity Board does not support any version of Digi's XBee Wi-Fi modules. Propeller Activity Boards marked Rev B or later support the S6B version of Digi's XBee Wi-Fi module, but not the S6 version. Unsupported modules may work, but there is a significant chance they will lose functionality.

— David Carrier
Parallax Inc.

Understood, thx for the information. Interestingly the XBee itself works fine, and it's just together with external power when the Ping misbehaves on one rev A but not on the other.