in the datasheet of the dwm3000, they mention the need for a keep out area of 10mm needed for the antenna the antenna’s on a PCB. Is it fine to instead have the antenna completely isolated by having it hanging off the board, like shown?
If I don’t plan to be resetting the device frequently and want to tie rstn to 3.3V, can I tie it directly or is a resistor needed? And can I also tie GPIO5/6 directly for SPI mode selection or are resistors also needed there?
Is it realistic to use the DWM3000 for short-range positioning (at max 30-40m away) for something like landing a model rocket? Or does model rocket motor plume cause significant interference to the extent where DWM is unusable? The rocket should be in line of sight at all times.
Yes, this is fine. In fact, this is how we have it on our DWM3000EVB and it is also mentioned in Figure 10 in the datasheet. Please make sure to review this section 6.1 of the datasheet regarding the keep out area.
It is not recommended to tie RSTn to 3.3V. Rather it should be connected to your host MCU so that you can reset the device as needed to enter a known state. Tying GPIO5/6 for SPI mode selection should be okay.
Regarding the rocket motor plume, I am not too familiar with its contents but I think it should be fine. However, I would encourage testing this out to understand the behavior and also the range in your scenario.
Some more information regarding GPIO5/6 can be found in the DW3000 Datasheet. If you are planning to use mode 0, that is the default and then you can leave the pins floating as they are internally pulled down by default. Otherwise, it is recommended to connect a pull up resistor to VIO_D supply.
Yes, I’ve seen section 6.1. The reason I was asking was because I couldn’t tell, is there a gnd pour needed 10mm away from the antenna on both sides? Or is 10mm just the recommended keep out distance if the antenna is lying on the PCB and cannot be floating?
is resetting the device usually needed that frequently during DWM3000 operation? I’m limited on pin count for my main IC, so if it’s something that can just be easily solved by turning the device on and off when there are any issues I’d prefer that.
Resetting isn’t normally needed.
Generally if while running the system has reached a state where a soft reset (sending the reset command over SPI) isn’t sufficient to recover then you’re probably at a point where you want to power cycle the full system just to be sure.
However it depends on how your system is designed, e.g. if you plan to support very low power modes of operation then having the processor being able to reset the UWB when waking may be the easiest way to ensure things are in a known state.
