DW1000 User Manual
© Decawave Ltd 2017
Version 2.12
Page 101 of 242
Field
Description of fields within Register file: 0x15 – Receive Time Stamp
FP_INDEX
reg:15:05
bits:15–0
First path index. This is a 16-bit value reporting the position within the accumulator that the
LDE algorithm has determined to be the first path. This value is set during the LDE algorithm’s
analysis of the accumulator data and is updated when the LDE execution has completed (when
the LDEDONE status bit is set). This value may be of use during diagnostic graphing of the
accumulator data, and may also be of use in assessing the quality of the received message
and/or the receive timestamp produced by the LDE. For more details of that please refer to
section
4.7 – Assessing the quality of reception and the RX timestamp
The first path (or leading edge) is a sub-nanosecond quantity. Each tap in the accumulator
corresponds to a sample time, which is approximately 1 nanosecond (or 30 cm in terms of the
radio signal’s flight time through air). To report the position of the leading edge more
accurately than this 1 nanosecond step size, the index value consist of a whole part and a
fraction part. The 10 most significant bits of FP_INDEX represent the integer portion of the
number and the 6 least significant bits represent the fractional part.
FP_AMPL1
reg:15:05
bits:31–16
First Path Amplitude point 1. This is a 16-bit unsigned value that is part of reporting the
magnitude of the leading edge signal seen in the accumulator data memory during the LDE
algorithm’s analysis. The amplitude of the sample reported in the FP_AMPL1 parameter is the
magnitude of the accumulator tap at the index 3 beyond the integer portion of the rising edge
FP_INDEX reported in this register. The FP_AMPL1 amplitude value can be used, in
conjunction with the FP_AMPL2 and FP_AMPL3 values reported in
, as part of assessing the quality of the receive timestamp produced
by the LDE algorithm. For more details please refer to section
4.7 – Assessing the quality of
reception and the RX timestamp
This value is updated when the LDE execution has completed (when the LDEDONE status bit is
set).
RX_RAWST
reg:15:09
bits:39–0
This 40-bit (5-octet) field reports the Raw Timestamp for the frame. This is the value of the
system clock (125 MHz) captured at the time of the first chip of the first PHR symbol. The
precision here is approximately 125 MHz, i.e. the 9 least significant bits are zero.
When the PHR has been decoded successfully (when the RXPHD status bit is set), the
timestamp will be available for reading. If a PHR error is detected, the timestamp will not be
updated.
7.2.24 Register file: 0x16
– Reserved
ID
Length
(octets)
Type
Mnemonic
Description
0x16
-
-
-
Reserved – this register file is reserved
register file 0x16 is reserved for future use. Please take care not to write to this register as
doing so may cause the DW1000 to malfunction.
7.2.25 Register file: 0x17
– Transmit Time Stamp
ID
Length
(octets)
Type
Mnemonic
Description
0x17
10
RO
TX_TIME
Transmit Time Stamp