DW1000 User Manual
© Decawave Ltd 2017
Version 2.12
Page 173 of 242
7.2.45.8
Sub-Register 0x2C:0A
– AON_CFG1
ID
Length
(octets)
Type
Mnemonic
Description
2C:0A
2
RW
AON_CFG1
AON Configuration Register 1
Register file: 0x2C – Always-on system control
, sub-register 0x0A is a 16-bit configuration register for
parameters within the always-on (AON) block. The fields of this register are interpreted inside the AON
block, and this can only happen after the register is loaded into the AON block via the UPL_CFG command in
Sub-Register 0x2C:02 – AON_CTRL
. The AON_CFG1 register contains the following fields:
REG:2C:0A – AON_CFG1 – AON Configuration Register 1
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
- - - - - - - - - - - - -
LP
OSC
_C
AL
SMX
X
SLEE
P
_CE
N
0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1
The fields of the AON_CFG1 register identified above are individually described below:
Field
Description of fields within Sub-Register 0x2C:0A – AON_CFG1
SLEEP_CEN
reg:2C:0A
bit:0
This bit enables the sleep counter. For correct operation of the sleep counter (down counter)
when loading a new value into the SLEEP_TIM field of
Sub-Register 0x2C:06 – AON_CFG0
recommended to set SLEEP_CEN to 0 before updating SLEEP_TIM. The recommended
operating procedure is then as follows:
(a) Set SLEEP_CEN (in AON_CFG1) to 0.
(b) Set UPL_CFG (in AON_CTRL) to 1, to apply this to the AON block.
(c) Program the new value of SLEEP_TIM (in AON_CFG0).
(d) Set SLEEP_CEN to 1.
(e) Set UPL_CFG to 1, to apply the new sleep time and enable the counter in the AON.
SMXX
reg:2C:0A
bit:1
This bit needs to be set to 0 for correct operation in the
default this bit is set to 1. The host system should set this bit to zero as part of initialisation or
controlling the entry of the DW1000 into the
state to ensure correct operation of the
LPOSC_CAL
reg:2C:0A
bit:2
This bit enables the calibration function that measures the period of the IC’s internal low
powered oscillator. The operating frequency of this oscillator depends on process variations
within the IC and also on the operating voltage and temperature. It should lie somewhere
between approximately 7,000 and 13,000 Hz. Using this LPOSC_CAL bit then it is possible
measure the period of the oscillation in counts of the IC’s internal XTAL_DIV2 clock, which runs
at a frequency of 19.2 MHz. Using this information it is then possible to more accurately
determine the value to set into the SLEEP_TIM field (of
Sub-Register 0x2C:06 – AON_CFG0
) for
a particular desired sleep period.
The recommended operating procedure for this is then using this is then is to:
(a) Ensure that the SPI operating frequency is set < 3MHz. (During procedure the system
uses the 19.2 MHz XTI clock which will not support higher SPI data rates).