decaWave DW1000, User Manual

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DW1000 User Manual
© Decawave Ltd 2017 Version 2.12 Page 58 of 242
= (N+1) x T
External
-T
1
+T
3
.
Where:

N is the number of external clock cycles since the SYNC signal captured in timestamp and
may be read from EC_RXTC in the RS_TS_EST field, see
Sub-Register 0x24:04 EC_RXTC .

T
External
is the period of the external clock.

T
2
is time from the rising edge of the external clock to the RMARKER.

T
1
is the time in ns reported by EC_GOLP in the OFFSET_EXT field, see Sub-Register 0x24:08
EC_GOLP .

T
3
the leading path delay, calculated by subtracting the raw receive timestamp from the
receive timestamp, the difference between these will give the leading path delay, see
Register file: 0x15 – Receive Time Stamp .
T
3
= RX_STAMP – RX_RAWST
6.2 External Power Amplification
In some geographic regions for certain situations (e.g. for emergency first responder use in ETSI UWB
regulations for EU) it is permitted to send at +20dB above the normal UWB regulation levels. To achieve
this with the DW1000 it is necessary to employ external amplification of the transmitted signal. The
DW1000 provides signals (using the GPIO lines in a special mode) to control the turn-on of the power
amplifier and to control the analog switching of the transmitter and receiver signal paths appropriately. This
mode of operation utilises the DW1000 pins EXTPA, EXTTXE and EXTRXE as configured via the fields MSGP4,
MSGP5 and MSGP6 in
Sub-Register 0x26:00 – GPIO_MODE .
Care should be taken when using this feature to ensure that necessary regulatory requirements have been
fulfilled.
There is a separate application note giving details of the external power amplification. This includes the
circuit diagram, details of configuration and various design considerations that apply. Please consult with
Decawave’s applications support team for details.
6.3 Using the on-chip OTP memory
The DW1000 has a small amount of one-time-programmable (OTP) memory intended for device specific
configuration or calibration data. Some areas of the OTP memory are used to save device calibration values
determined during DW1000 testing, while other OTP memory locations are intended to be set by the
customer during module manufacture and test.
For example, an OTP memory area is reserved for customers to programme the EUI that is loaded into
Register file: 0x01 – Extended Unique Identifier as the IC comes out of reset (see Register file: 0x01 –
Extended Unique Identifier for details of the EUI functionality).
This section lists the OTP memory areas defining their functionality and describes the algorithm for
programming values into the OTP memory, and how to read values from the OTP memory. Access to OTP
memory is achieved using
Register file: 0x2D – OTP Memory Interface .