Communicating to Bridge Node with SPI

Hi :slight_smile:

I´m trying to comunicate with the Bridge Node using an Arduino. I saw in “Product_and_Design_Documents” → “DWM1001_System_Overview.pdf” (page 13) that the Bridge Node comunicate with the Linux Host by SPI TLV, but there´s no TLV to get the informations that the bridge sends. How can i comunicate with the Bridge by SPI?

Hi Rarafa,

The interface with the bridge node is currently not documented, so there is no straightforward way to communicate with it.


Hey Yves_Bernard.

I was reading the “Dwm1001 Firmware API Guide” and i found the TLV command “dwm_backhaul_xfer”. What about it? Can i receive the datas from the Bridge node with this?


Well the issue is that the data to send with the dwm_backhaul_xfer api is not documented, making it not very useful.



Sorry to disturb but I can’t get any reply from the forum for the question I posted and base on the questions you answered in the forum, I believe you might have better idea on what I faced.

I also understand that quite some posts asking similar questions but the answer is “the backhaul command is not documented, making it not useful”, but could I have the pseudocode on how to set the LED from the start of the initialisation to turning off the LED for example?

I have a setup of 3 anchors, and 2 tags, which works fine with the raspberry bridge with the dwm image. From the web interface, I could set the setting on the Tags, such as turning the LED off, and other setting without using the android apps via HP.

Now I am trying to use own program to communicate with the Tags from the Bridge (RaspPi) without using the DWM daemon (either I kill it or use raspbian image), after setting up all the necessary spi module etc, I am able to read the status, location, etc from the Tags with the backhaul xfer command (0x37 0x02 …) and decode them to what I need, but I am now stuck to send the command to change the setting of the Tags such as turning the LED off.

From the searching and experiments, I notice that the daemon is running through some initialization for the UMB network, such as the loop from dwm_nodeid_get, dwm_panid_get, dwm_init_cfg_get, dwm_cfg_get, dwm_cfg_anchor_set, dwm_reset… and another loop of setting the panid and secure key etc… .

I also notice following the initialisation, there are some xfer command which sent data to the tags, and also the anchors, but i tried to mimic the sequence but i still fail to set the LED of the tag.

Hope I could get some answer for this.



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Hi chinluh,

Could you please elaborate about the communication using the backhaul? I can’t wrap my head around the way the data acquired needs to be decoded and in what kind of sequence it should be read.