DW1000 User Manual
© Decawave Ltd 2017
Version 2.12
Page 149 of 242
ID
Length
(octets)
Type
Mnemonic
Description
27:20
2
RW
DRX_SFDTOC
SFD detection timeout count
Register file: 0x27 – Digital receiver configuration
, sub-register 0x20 is used to set the 16-bit SFD detection
timeout counter period, in units of preamble symbols. The SFD detection timeout starts running as soon as
preamble is detected. If the SFD sequence is not detected before the timeout period expires then the
timeout will act to abort the reception currently in progress, and set RXSFDTO event status bit in Register
file: 0x0F – System Event Status Register. SFD timeout events are also counted in
, assuming that counting is enabled by the EVC_EN bit in
The purpose of the SFD detection timeout is to recover from the occasional false preamble detection events
that occur. By default this value is 4096+64+1 symbols, which is just longer the longest possible preamble
and SFD sequence. This is the maximum value that is sensible. When it is known that a shorter preamble is
being used then the DRX_SFDTOC value can be reduced appropriately. It is also recommended to further
reduce the DRX_SFDTOC value by the PAC size as one PAC size of the preamble length will be lost as part of
the preamble detection.
WARNING: Please do NOT set DRX_SFDTOC to zero (disabling SFD detection timeout). With the SFD
timeout disabled and in the event of false preamble detection, the IC will remain in receive mode until
commanded to do otherwise by the external microcontroller. This can lead to significant reduction in
battery life.
7.2.40.8
Sub-Register 0x27:22
– DRX_RES3
ID
Length
(octets)
Type
Mnemonic
Description
27:22
2
-
-
Reserved
Register file: 0x27 – Digital receiver configuration
, sub-register 0x22 is a reserved area. Please take care not
to write to this register as doing so may cause the DW1000 to malfunction.
7.2.40.9
Sub-Register 0x27:24
– DRX_PRETOC
ID
Length
(octets)
Type
Mnemonic
Description
27:24
2
RW
DRX_PRETOC
Preamble detection timeout count
Register file: 0x27 – Digital receiver configuration
, sub-register 0x24 is used to set the 16-bit preamble
detection timeout period, in units of PAC size symbols. The default/reset value is zero which disables the
preamble detection timeout. The preamble detection timeout starts running as soon as the receiver is
enabled to hunt for preamble. In the case of delayed receive (as commanded using the RXDLYE control in
Register file: 0x0D – System Control Register
) the preamble detection timeout starts after the delay when the
receiver actually turns on to hunt for preamble. If a preamble sequence in not detected before the timeout
period expires then the timeout will act to abort the reception currently in progress, and set the RXPTO
event status bit in