Testing Ronja 10M Metropolis

We are going to test the electronics. You should get to the end without problems. If there is a bug and you can't identify it and repair it, ask on the mailing list.

Powering AUI Forte for the first time

Plug AUI Forte alone (without RX and TX) into the AUI network card. The yellow light should shine. If it shines dimly or doesn't shine then there's a short circuit on the power: in such case disconnect it immediately and check the circuit again. You can also measure the power consumption of the AUI Forte by unsoldering the power wire inside and sticking ampermeter probe into the resulting gap. The typical value is 160mA.

The red light shall not shine even not dimly. If it shines, there is a bug in the transmitter path logic. Check the topology and component values again.

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Testing AUI Forte under power

If you didn't already do it, test AUI Forte BER under power. If you couldn't meet the prerequisites, test AUI Forte packetloss instead.

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Powering Metropolis for the first time

Now disconnect AUI Forte from the network card and connect receiver and transmitter according to the picture. Plug the AUI Forte back into the network card. Again check the yellow light and you may also check the total consumption: it should be max. 300mA.

Check of measurement points

Check all voltage measurement points except current one, because for measuring a current you have to break the circuit. Measurement points are those small tables in the schematics with various variables. Check the values in all three boxes: Twister, Receiver, Transmitter. Determine if the measured voltages are in the specified range. The voltages are measured against ground (i. e. the tin of the can). The values should be all OK. If they are not, perform correctness checks of the affected module once more. If the problem still persists, ask on the mailing list.

Testing RSSI operation

Check whether the TX diode shines. Connect 200mV voltmeter into Receiver's RX level DC measurement (Received Signal Strength Indicator, RSSI). Check whether the multimeter readout reacts to the light strength from the transmitter.

Preemphasis setting

Do preemphasis test of Metropolis.
Change value of R8 according to the result:

Result Action
LED shines too long Increase R8
LED shines too short Decrease R8
OK Done

LED current setting

Let the transmitter shine without sending any packets into it. Measure DC voltage across R11 (default value 8.2 Ohm) and then switch off the transmitter completely by plugging the AUI Forte out of NIC. Measure the real value of the R11 (default nominal value 8.2 Ohm). Compute the DC current flowing according to Ohm's law as I=U/R. If it is greater than 68mA, replace R11 (8R2) with R14 (10 Ohm). Reconnect the power of AUI Forte and continue with testing by sending ping's.

Performance Measurements

Do at least one from the following Metropolis tests (if you don't have prerequisites for one, then go to another etc.):

If something is wrong

If you are getting substantially smaller ranges (for example 0.7m for SFH203), something is wrong.

The input transistor of the receiver (Q101, BF908 or its equivalent) can be broken-through. It is caused by inappropriate handling: the device is static electricity sensitive. It can be caused also by soldering with an iron with ungrounded tip or transformer soldering gun can generate spikes during switching. This sometimes manifests as a voltage greater than 0V on P103. My healthy receiver has 0.1mV on P103.

A breakthrough of G2 sometimes manifests itself as a receiver that is oscillating (doesn't work at all or has inferior range) where the oscillations cease when C103 is removed from the circuit.

Breakthrough of Q101 can be fixed only by replacing with another one and obeying the rules for manipulation with static electricity sensitive devices.

Range reduction

If you plan to use Ronja on a link less than 1/4 of nominal distance, then perform range reduction now.

Mount Thermal Shields

Now mount the thermal shields to both the receiver and transmitter using four M3x10 screws and 12 M3 nuts. Tighten it all together firmly.