Hello everyone,
I am interested in using UWB technology in the automotive industry for safety applications.
I made a board with a DW1000 and a STM32F415 MCU and I ported the DecaWave’s Two Way Ranging application on my card; I’m using the ECLIPSE/gcc environment + CubeMX. Now I’m testing my board and I’m using an EVB1000 as a reference board.
I have this problem (the two boards are set in mode 3, channel 2):
When my board works as TAG and the EVB1000 as ANCHOR, the EVB1000 always detects a PHR error on receiving the BLINK message (the ANCHOR SYS_STATUS register reports 100000000001011100000011); instead, when the EVB1000 acts as TAG, the transmission of the blink message is received without errors by the ANCHOR and, after some RANGE-INIT message retransmission, the Two Way Ranging application starts and works correctly.
My board is equipped with a 0.5ppm TCXO connected on XTAL1; the spectrum of the transmitted signal seems to be correct (centered on 3.9 GHz with 500MHz of bandwidth). Furthermore, the TX/RX configuration parameters (checked by reading the SYS_CFG, TX_FCTRL, RX_FINFO registers on both boards) are the same.
Where could the problem be?
Why I have PHR errors on receiving the BLINK message and what other tests can I perform to figure out where the problem is?
I finally solved the problem. I had powered the TCXO via a 3.0V LDO, but the DW1000 pin 47 (VDDBATT) was still connected to VDD_3.3V. Looking better at the DW documentation, both the data sheet (on page 8) and the aph001 (on page 23) advise instead to connect VDDBATT to the TCXO power supply. After this change I have no more errors in the transmission of the PHR and the DecaRanging application works perfectly on my HW.
However, I’m a little surprised, because this was the behavior before the change:
[font=Courier New]±--------------------+ ±--------------------+ [/font]
[font=Courier New]| MyBoard | | EVB1000 | [/font]
[font=Courier New]| TAG (Mode 3) ±------> ANCHOR (Mode 3) |[/font]
[font=Courier New]| ex_03a_tx_wait_resp | | ex_03b_rx_send_resp | [/font]
[font=Courier New]±--------------------+ ±--------------------+[/font]
[font=Courier New] PHR ERRORS: [/font]
[font=Courier New] SYS_STATUS register 100000000001011100000011[/font]
[font=Courier New]±--------------------+ ±--------------------+ [/font]
[font=Courier New]| EVB1000 | | MyBoard |[/font]
[font=Courier New]| TAG (Mode 3) ±------> ANCHOR (Mode 3) |[/font]
[font=Courier New]| ex_03a_tx_wait_resp | | ex_03b_rx_send_resp | [/font]
[font=Courier New]±--------------------+ ±--------------------+[/font]
[font=Courier New] PHR OK:[/font]
[font=Courier New] SYS_STATUS register 100000000110111100000011
[/font]
So I ask the DecaWave technicians: why did my mistake affect the transmission only?
I would expected that the VDDBATT pulse noise should have a greater impact on the reception phase…