Frequently Asked Questions - System Design Implementation

 

Our application note  APS002 min power in DW1000_systems explains the different design considerations to take care of when power consumption is of importance.

 

APS002 is available from our website: http://www.decawave.com/support

 

As the package is an industry standard 48 pin QFN 6 x 6 mm with 0.4 mm pitch and exposed ground paddle, we refer customers to JEDEC specification J-STD- 020.1 (March 2008).

This specification is available from the following link: http://www.jedec.org/standards-documents/ PCB land-pattern libraries are available for 3 common CAD packages on the Decawave website.

 

Decawave and the IEEE 802.15.4a standard specify +/-20ppm crystals. Other crystals meeting this specification should also work provided the guidelines in the DW1000 datasheet are followed. Alternate crystals should of course be tested before committing to a design.

 

We have an application note which explains the different design considerations to take care of, to maximise communications range.

See APS017 max range in DW1000 systems available from our website: http://www.decawave.com/support

 

Yes, we provide an abstracted view of the DW1000 register set to the software programmer. This API includes a set of examples demonstrating how to use the API to perform some of the most commonly required operations.

This API and the software source code can be downloaded from: http://www.decawave.com/support/software

 

In order to maximise range DW1000 transmit power spectral density (PSD) should be set to the maximum allowable for the geographic region. For most regions this is -41.3 dBm/MHz. The DW1000 provides the facility to adjust the spectral bandwidth and transmit power in coarse and fine steps.

See for further details APS023 Transmit Power Calibration & Management available from our website: http://www.decawave.com/support

 

For software developers and firmware engineers to debug their software we have an application note. This application note describes step by step debugging of the applications and drivers which control the DW1000.

See APS022 Debugging DW1000 based products systems on our website: http://www.decawave.com/support

 

To assist customers with for example PCB layout and number of recommended layers of a DW1000 based product we have APH001 DW1000_HW_Design_Guide. This application note is a comprehensive document about the do’s and don’ts on HW design using our IC

Please refer to application note “APH001 DW1000_HW_Design_Guide  available on http://www.decawave.com/support#term5

 

The DW1000 chip provides a complete PHY layer but does not implement a full MAC, although it does provide some MAC features such as address filtering. In the context of RTLS tags you should carefully consider the necessity for a MAC scheme because these generally require each node to listen for synchronizing broadcasts of some kind. This increases power consumption and reduces battery life.

For more information see the DW1000 IC user manual Chapter 5 “Media Access Control (MAC) Hardware Features” which is available from http://www.decawave.com/support#term5

 

Processor requirements are highly dependent on the end application. 

For a Two-Way ranging (TWR) mobile tag a microprocessor with at least 16k of flash and 4k of RAM should be used to run Decawave’s TWR demo application.

For TDoA based mobile tag application, a smaller microprocessor e.g. with 4-8k of flash and 1-2k RAM may be used.

If you want to minimize system power consumption we recommend using a microprocessor with a fast start-up time and an SPI interface capable of the maximum 20 MHz rate supported by the DW1000.

 

The example EVK and TREK application software source code is built on the ARM Cortex M3 based microcontroller (STM32F105RCT6) which is a 32-bit, little-endian processor. Areas to be considered when using an 8-bit microcontroller are described in Application Note: “APS019 Driving DW1000 from 8-bit MCU v1.0” available on http://www.decawave.com/support#term5.