To test an atben board, place a reference atusb board into
the PC, insert the atben board into the Ben, and place both devices
at the same location and with the same orientation used when acquiring the
signal strength profile.
The two devices should be about 1 m apart. Their vicinity should be free
from obstructions and items that can reflect or absorb RF signals. Such
items include metal chairs and human bodies.
Location and orientation should
be easily reproducible, e.g., by marking the device's edges on the table
with tape. Other transmitters in the 2.4 GHz band will interfere with
measurements and should be kept as far away and as inactive as possible.
The test setup is the same as for atben testing, except that the
DUT and reference device roles are reversed.
The test process is started from the directory ben-wpan/prod/
with
make ben
for an atben DUT and with
make usb
for an atusb DUT. It performs the following steps:
- Enumeration (atusb only)
- LED (atusb only; not yet implemented)
- GPIO scan (not yet implemented)
- Identification
- Crystal frequency
- Spectrum
- Receive
- Send
Of these tests, only "LED" and "Spectrum" require operator input. The
other tests run without interaction.
The test scripts log the commands they execute and their output in the
file _log.
The enumeration test verifies that the atusb board has been
identified by the PC's USB stack. If this test fails, the board may
not be plugged in correctly or it may be missing the firmware. A
board that has passed both stages of the firmware flashing process
should always pass the enumeration test.
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This test reads the transceiver's registers that contain values identifying
the manufacturer, the chip's part number, and the chip revision. If an
atusb board fails this test, this probably means that the MISO signal
between transceiver and the microcontroller has a problem.
On atben, failure may simply indicate an improperly
inserted board. Eject the board, re-insert, and try again. If the test
keeps on failing, this may indicate a problem with MOSI, MISO, nSEL,
SCLK, the power supply, the crystal oscillator, or possibly the position
of the transceiver chip.
Note: this test is meant as a higher level test. The GPIO test should
eventually provide more detailed results for problems with the SPI interface.
This test measures the frequency of the crystal oscillator in the DUT.
On atben, it does this by transmitting packets, and measuring
the time between the SLP_TR pulse that starts the transmission and the
interrupt signaling the end of the transmission.
On atusb, the microcontroller counts the clock cycles and the
number of cycles is compared with the PC's NTP-disciplined clock.
If this test fails, this may indicate that the load capacitors of the
crystal are missing, badly soldered, or have the wrong value. It could
also mean that the crystal itself is defective. Another possible cause
of oscillator malfunction could be flux residues bridging traces.
The fault analysis page has more details on
testing the crystal oscillator.
The spectrum test measures the reception of a signal sent from the
reference device to the DUT. It does this across the entire frequency
range in which the WPAN boards operate, allowing the detection of
frequency-dependent anomalies.
This test depends on numerous external factors, like the exact position
and orientation of the two devices with respect to each other, and the
presence of obstacles and conductive items (metal, people, etc.).
Because of the test's sensitivity
to environmental factors, the operator needs to decide when the result
represents a valid measurement and then confirm the result shown.
The image below shows the typical display during the spectrum test:
the white line is the measured signal strength. The red lines indicate
the minimum and maximum allowed values. The green circle in the upper
right corner indicates that the signal strength is within the limits.
A downward-pointing red triangle would indicate that the signal is too
weak, an upward-pointing yellow triangle would indicate that the signal
is too strong.
To finish the test, the operator must type either P, F,
or Q in the window shown. P means "pass" and can only be
entered if the measurement is within the limits. F means "fail"
and can only be entered if the measurements is outside the limits.
Q, quit, can be entered at any time and also fails the test.
In the receive test, the reference device sends a number of frames to the
DUT. The test program verifies correct reception of all the frames. A
device that has passed all the preceding tests should not encounter
problems in the receive test. If it does, there may be a problem with
the bypassing of the transceiver's 1.8 V supplies.
The send test is like the receive test, but with the DUT acting as the
sender and the reference acting as the receiver. If a device passes the
receive test but fails the send test, there is probably an issue with
the bypass capacitors of the analog 1.8 V supply.
Another possible cause could a problem with the SLP_TR signal. The
GPIO test should eventually catch this issue, but it may currently
remain undetected until the send test.
