Getting the tags location using the TWR

prajju_hari · November 19, 2019, 6:02am

Hi,
I am trying to calculate the distance between two tags present in the network with the help of TWR.

I would like to know if the location of the tag is present in the TWR slot superframe or somewhere else. If it is present in the superframe, how will i be able to access it from the superframe?

Thanks and Regards,
Prajval S H

seppe · November 19, 2019, 5:26pm

Hello Prajval

Could you clarify what hardware / software you are using?

Greetings
Seppe Stas

prajju_hari · November 19, 2019, 7:02pm

Hi Seppe
Thank you for your response.
I am using the DWM1001 hardware and trying to get the location of the Tag with the help of TWR employed with the device.

prajju_hari · November 20, 2019, 5:38am

Hi Seppe

My requirement to get the location of the tags using TWR and check if any tags present in the network is close to each other and generate a message when two tags are close to each other.

The software which i am using is segger embedded studio for arm.

Thanks & Regards
Prajval

Kenneth_Dwyer_DW · November 20, 2019, 7:14am

Hi,

Please clarify that you are using PANS (The DWM1001 RTLS stack) our your own TWR code variant?

Ken

prajju_hari · November 20, 2019, 7:50am

Hi Kenneth,

Thank you for your response.

I found the code on the github website for calculating the distance between an initiator and responder on two way ranging. (https://github.com/Decawave/dwm1001-examples)

I tried flashing the examples given in the above link. The app was unable to detect the device after flashing.

Can you please help me out with instructions on how to flash the device with examples found in the above link?

Thanks & Regards,
Prajval

Kenneth_Dwyer_DW · November 20, 2019, 2:02pm

Prajval,
The APP works with PANS, the examples from Github do not work with PANS.
Ken

prajju_hari · November 20, 2019, 4:46pm

Hi Ken

Thank you very much for the information.

Is it possible to get the access for the TWR slots so that i can get the location of the tags which are close to each other as it is already using TWR technique for communication?

Prajval

prajju_hari · November 20, 2019, 4:59pm

Hi Ken

Can you please explain why can i not use the examples provided on the github website work with PANS?

Prajval

seppe · November 20, 2019, 5:27pm

Hi Prajval

The examples on Github are simple TWR examples. For this example, one of the devices needs to run the “Initiator” firmware ( ss_twr_init) and the other device the “responder” firmware (ss_twr_resp). The responder will print the distance between the 2 devices over UART.

PANS is a more complete demo that can provide absolute location using fixed infrastructure based on TWR. The Android app only works with the PANS firmware. It is possible to configure one of the devices as a “tag” and an other device as a “anchor”, set up as initiator, allowing to just measure the distance between the 2 devices. Measuring the distance between 2 tags is only possible if a network with 3 or more anchors is set up.

If you have a network set up with >3 anchors it should be possible to calculate the distance between 2 tags based on their absolute position. I don’t think it is possible to do TWR between 2 tags (but I could be wrong in this).

prajju_hari · November 21, 2019, 5:00am

Hi Seppe

I tried flashing the device with the initiator program.

The app was not able to detect the device when i started the device discovery on the app for creating the network.

Is there a starting address that i should mention for flashing the user code to the device?

seppe · November 25, 2019, 5:31pm

Hello Prajval

Again, the examples on Github, including the initiator and responder TWR samples, do NOT work with the PANS Android app.

The only firmware that can be used with the app is the PANS firmware that can be found here: https://www.decawave.com/1001-license/

prajju_hari · November 27, 2019, 4:57am

Hi Seppe

Thank you for your response.

The examples on the github are working.

I tried using dwm_node_id_get API provided in the API guide pdf. The API does not seem to be working. Is is possible to use the API’s provided in the API guide in the github examples. And can i use more responders and get the distance from the initiator.

Thanks
Prajval

seppe · December 2, 2019, 5:43pm

Hello Prajval

The API guide you mentioned is the API guide for the PANS firmware. Sorry for the confusion, I agree the title of this document can be somewhat misleading.

The examples on Github use revision 2.04 of our deca_driver library. The documentation for this can be found in the “DW1000 Device Driver API Guide” contained in the The DW1000 Application Programming Interface software package, see DW1000_Software_API_Guide_rev2p4.pdf.

I would be possible to create a more advanced setup with multiple responders, but the example we provide on Github does not support this. PANS does provide a more advanced RTLS setup, but we can not release the full source code of this system. It is however possible to connect an external MCU / device to the DWM1001 and use the PANS firmware API over UART, SPI or BLE.

I hope this answers your questions
Seppe

prajju_hari · December 3, 2019, 5:41am

Hi Seppe,

Thank you so much.

I have got all the answers to my questions. This helped me a lot. Thanks again.

Prajval