Perhaps more on point with the original request, there are other methods for XTAL_TRIM calibration which require very little equipment (no spectrum analyzer) and no use of GPIO0 62.4 MHz output (which has to be measured in some way, so some connection and equipment). It would be best if you didn’t need expensive equipment and didn’t need to connect to the device under test.
The basic idea is to compare the timing of the node under test with a known accurate node, say one with a TCXO, or a node modified with an OCXO for even better accuracy, or a stable signal generator. So many things in the DW1000 are tied to the clock that all you need to do is find something to compare between nodes.
Idea #1:
Have the device under test transmit two packets with a precise SYS_TIME spacing. Receive those two packets at the known good node and record the receive times. The difference in the two transmit times and two receive times indicate the crystal offset and XTAL_TRIM can be adjusted.
Example using made up numbers:
DUT transmits at 0x00 0000 0000
DUT transmits at 0x00 03cf 0000
Delta time of 63,897,600 ticks.
Known device receives at 0x23 4562 9b4c
Known device receives at 0x23 4931 9b8b
Delta time of 63,897,663 ticks.
The receive measured delta time is greater by 63 ticks, which means the device under test is slow by 1 ppm.
You can also do this the other direction, transmit from the known device to the device under test. This method is highly accurate either way given the ~100 ps time noise in the time measurement. For example, for about 0.1 ppm accuracy, you need to send packets every 1 ms which is plenty for XTAL_TRIM work.
Idea #2:
The DW1000 has some offset measurement features such as DRX_CAR_INT and RX_TTCKO. Have one node transmit to the other and then use those features to measure the offset in the two nodes. Adjust XTAL_TRIM for best fit.
Mike Ciholas, President, Ciholas, Inc
3700 Bell Road, Newburgh, IN 47630 USA
mikec@ciholas.com
+1 812 962 9408