Did Parallax bother to verify the layout of the SX-KeyRing?
wbahn
Posts: 13
I just got the keyring today and noticed that something didn't quite seem right.
The connector that the SX-Key plugs into is very clearly marked on the silk screen with the pin assignments. Holding the keyring so that the SX-Key comes in from the right (which makes the power adaptor come in from the bottom), the pins are labelled (from top to bottom) OSC1, OSC2, Vdd, Vss. But the connector for the device being programmed is not labelled on the silkscreen at all. There is only a Vss label in copper near the top pin.
It seemed rather odd that an in-line adaptor would make you flip the orientation of the SX-key relative to the board being programmed. So I looked at the traces and the OSC2, Vdd, and Vss pins of the SK-Key connector had tracks leaving the pins on top copper while the OSC1 pin is tied to the large plane on bottom copper. Seems very strange.
Tracing those tracks shows that the pin labels on the SX-KEY connector are almost certainly reversed.
To verify my suspicions, I connected power and, sure enough, 5V appears at the OSC2·pin relative to the OSC1 pin which is clearly connected to ground.
The board (Rev A) is marked with a copyright of 2000. Does this really mean that Parallax has been shipping a board, for six years,·with connector pin labels, on an unpolarized connector, reversed?
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The connector that the SX-Key plugs into is very clearly marked on the silk screen with the pin assignments. Holding the keyring so that the SX-Key comes in from the right (which makes the power adaptor come in from the bottom), the pins are labelled (from top to bottom) OSC1, OSC2, Vdd, Vss. But the connector for the device being programmed is not labelled on the silkscreen at all. There is only a Vss label in copper near the top pin.
It seemed rather odd that an in-line adaptor would make you flip the orientation of the SX-key relative to the board being programmed. So I looked at the traces and the OSC2, Vdd, and Vss pins of the SK-Key connector had tracks leaving the pins on top copper while the OSC1 pin is tied to the large plane on bottom copper. Seems very strange.
Tracing those tracks shows that the pin labels on the SX-KEY connector are almost certainly reversed.
To verify my suspicions, I connected power and, sure enough, 5V appears at the OSC2·pin relative to the OSC1 pin which is clearly connected to ground.
The board (Rev A) is marked with a copyright of 2000. Does this really mean that Parallax has been shipping a board, for six years,·with connector pin labels, on an unpolarized connector, reversed?
·
Comments
Now that I know that a manual exists, I was able to track it down. Thanks.
Still seems odd that they are selling improperly labelled parts after six years.
I'll make sure we add a notation on the web site. We built this product in a large quantity to keep our costs under control. The error carried through from the prototype to production.
Sorry if it caused some trouble for you. Let me know how I can rectify the problem for you and I'll do so.
Sincerely,
Ken Gracey
Parallax, Inc.
But this is a good point to ask a question - what are the consequences of connecting the programmer backwards. My guess is that there's a fair chance that nothing bad will happen, but I'm not about to test out that theory.
SX-Key in upside down => SX-Key not found on COM1
Turned it over right side up and it still programmed. No consequence.
We'll certainly make sure the web description notes this silkscreen issue. Thanks for pointing it out.
Ken Gracey
Parallax, Inc.