Calibration Voltage Problem

[Tony Abbey]

Continuing trying to get my system going with the Raspberry Pi. I reported strange values on the analogue inputs, so decided to do a recalibration.

However, there looks to be something very wrong - the o/p signals that should be 2.75V, 0, or -2.75 are all sitting at either -2.79V before cal starts or  or -5.04V during calibration - it looks to me as though a 5V supply has gone missing. I'll check through the circuit, but if anyone knows what the problem might be, please let me know.

Tony

[Tony Abbey]

Answering my own post, I have solved the problem. Looking at J5 the test connector, I could see that +5.5V was appearing at the output of the DC-DC converter, but not after the inductor L14. Taking the LPC-Link 2 processor board off the LabTool I was able to see that L14 had not been properly soldered on the board. As it seemed easier to fix the problem than return the board to Cool Components, I decided to refit the inductor. Unfortunately, a tag came off when moving it, but I managed to fit a wire ended 180uH inductor instead. Attached are the before and after pictures. Now we get 5.5V, and calibration works OK. Now the analog inputs look good, and I can also get a signal on D0.

Onwards we go. Thanks to Embedded Artists for making this nice board and also providing Raspberry Pi code.

Tony

[Anders Rosvall]

Hi Tony and all of you following this forum,

We at Embedded Artists very much apologize for the problems Tony have had. It definitvely seems to have been a bad solder joing at L14.

If something strange happends with the signal levels, like Tony described, it is a good start to measure the power supply voltages on J5 (on the LabTool board).

We also recommend to contact us via our support ticket system, in case of problems.

Kind Regards,

Anders

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