Propeller Activity Board: The Current Shortage
Jessica Uelmen
Posts: 490
Wanted to pop in quickly and give you a quick update on the status of the Activity Board. The out of stock question had been asked about previously, and while initially we were out of inventory, things have changed a bit since then. Unfortunately, the worst has happened and we've uncovered a slight design issue.
Specifically, we've seen intermittent noise in the power supply on some boards, which causes XBee modules to not operate correctly when connected to the XBee header. The solution lies in a capacitor part change, which we are in the process of implementing.
However, this issue isn't present on all boards. Boards in the initial shipment are fully functional, and a only portion of the more recent shipments (after 5/17/13) are affected.
I've attached a test to this post which allows you to test whether your board is exhibiting these symptoms (please be sure to follow the directions at the top). If it is, please contact sales@parallax.com for a hassle-free replacement. Distributors, you'll be contacted by your sales rep directly for replacement information.
Any questions, comments, or concerns? Please post 'em here. We want to make this right for people as quickly as possible so that you can get back to creating! And of course, we're very sorry for any inconvenience this causes.
Specifically, we've seen intermittent noise in the power supply on some boards, which causes XBee modules to not operate correctly when connected to the XBee header. The solution lies in a capacitor part change, which we are in the process of implementing.
However, this issue isn't present on all boards. Boards in the initial shipment are fully functional, and a only portion of the more recent shipments (after 5/17/13) are affected.
I've attached a test to this post which allows you to test whether your board is exhibiting these symptoms (please be sure to follow the directions at the top). If it is, please contact sales@parallax.com for a hassle-free replacement. Distributors, you'll be contacted by your sales rep directly for replacement information.
Any questions, comments, or concerns? Please post 'em here. We want to make this right for people as quickly as possible so that you can get back to creating! And of course, we're very sorry for any inconvenience this causes.
Comments
Sounds like the capacitor has tombstoned. A picture would be interesting.
I tried your test on my Activity Board and both LEDs remained lit. I guess I got one of the good ones!
David
My camera with the good macro function hasnt been used in a long time, the focus mechanism appears to be siezed up. I could try taking a picture at work through the microscope. There is an indentation in the solder where the lead was setting. If other boards are doing the same thing, but the capacitor doesn't get knocked off, then it would be hard to find the problem visually.
propMaker,
PM me your shipping address and I'll get a good board to you ASAP. No need to go back through Propeller Powered.
Hal Albach,
We're hoping to get boards back in stock within the next couple weeks. We have many boards on backorder, so we'll be filling those orders before you'll see stock on the website.
I'll watch for the "reseller annoucement" regarding how we should handle this.
Thanks!
Jeff
It looks like your board was damaged in transit, since the solder in the he pad for the capacitor has a hole matching the shape of the lead. The electrolytic capacitor is big enough to give a lot of leverage, so external force can pry it off the board. Normally the lead would lift the pad with it too, but in this case it is connected to a ground plane through several wide traces that hold the pad firmly in place. The test Jessica posted only tests the 3.3-volt supply, which is the one that the XBee modules use. Without the electrolytic capacitor you pictured, your 5-volt supply may be noisy or react poorly to changes in current, but the 3.3-volt supply may still work fine.
If a board has a noisy 3.3-volt supply, you won't be able to see anything physically different, because it is due to an interaction between the voltage regulators, but if you haven't damaged your ears from listening to loud rock music, you may be able to hear the problem. Most types of ceramic capacitors are mildly piezoelectric, so they vibrate as the voltage changes. If the board has electrical noise, the ceramic bypass capacitors will convert it to audio noise, and if you have a sensitive ear, you will hear an 11,000 to 15,000 Hz whine.
— David Carrier
Parallax Inc.
(Note: Parallax has ALWAYS helped us with any that arrived here with any noticable damage!)
I've started packing them in multiple layer of bubble pack from Propellerpowered in the attempt to make sure they arrive to our customers in good shape.
@propMaker: was your well packaged when it arrived? Thanks for the pics, I'll add cap inspection to my inspection list here.
Jeff
-Phil
It was packed very well. I didn't see any damage to the outside of the package either.
PMing you.
Jeff
Hal
Had time this morning to look at the Activity Board with a scope and found some interesting items. Notably, the board nearly always passes the test when powered by the USB port. When I power the board from a 7.2 volt battery or wall wart then the board ALWAYS fails the test. When powered with the battery the +5 rail has an 800 mili-Volt P-P AC pulse riding on the +5 at a 20KHz rate. The 3.3 Volt rail has a 400 milli-Volt sawtooth waveform at the same 20KHz rate. On the scope Vin is clean and steady at 7.2 Volts.
When USB powered, both rails are clean.
I placed a 100uf Cap from +5 rail to ground in the proto area and nothing changed
I placed a 10uF Cap from the 3.3 rail to ground in the proto area and all the pulses and sawtooths disappeared, and the board passes the test every time with the 7.2 Volt battery as the power source. The ADC reading the 3.3 rail fluctuates +/- 2 milli-Volts.
Wonder if anyone else with a failing board has the same result?
Here are the scope images...
+5 rail............... 3.3 rail
Scope settings: 20us/div, 200mV/div, AC coupling
Hal
Hal