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forester
2 Posts |
 Posted - 17 Nov 2003 : 13:07:55
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We're trying to bring up a new AGX development system.
Without connecting to J40, the system works. When we try to connect a small adapter board to J40, the board locks and will not boot (nothing on the debug port).
The adapter board only has connections for: GND, TX, RX for all four ports. Ports A & B are connected to an RS-232 level driver, while ports C & D are connected to 3.3V logic drivers. The adapter board has a separate 3.3V regulator. All other pins besides GND, TX (A-D), and RX(A-D) are open.
Any suggestions? I verified that my ground pins are the same as the ground pins on the AGX board using a continuity tester (to verify my understanding of the pinouts). I haven't downloaded a data sheet on the QuadUART to bell out those connections yet.
John |
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akidder
1519 Posts |
Posted - 17 Nov 2003 : 13:53:25
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There could be any number of things going on. Here are a couple to check:- Connector Orientation
Do pins 1 and 2 of your board connector match pins 1 and 2 of the AGX?
- Signal Direction
Did you connect your RX lines to the AGX TX lines? The TX/transmit lines specified in the manual are signal outputs.
- Pin Voltages
Do pin voltages match expectations? I.e. With your board not connected, EIA-232 output pins should be +/-6V; input pins should be floating.
- System Power Supply
Does installing your board cause the 3.3V system power supply to stay low? You can test 3.3V power at JP3 pin 1 (behind the reset switch).
These are a few starting points. If these don't provide the insight you need, your best bet is to email us directly or give us a call to troubleshoot the issue. |
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akidder
1519 Posts |
Posted - 18 Nov 2003 : 14:43:36
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Resolution: Connector pin numbering
It turned out that the issue was not at J40, but on the power cable made to connect to J2. Keep an eye out for pin 1 on our products.
Manufacturers can number the pins of similar parts differently; Molex even uses different pin numbering within the same parts family. In this case, the pinout for the six-pin Amp/Molex header that we used was opposite from what forester had used in his cable. We were both using published manufacturer pinouts.
Pin 1 on all our connectors is always indicated by a square pad on through-hole components and a mark or number on surface-mount ones. |
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