decaWave DW1000, Руководство пользователя

Страница: 17 / 242

DW1000 User Manual
© Decawave Ltd 2017 Version 2.12 Page 17 of 242
State Name State Description
DEEPSLEEP
With the exception of the OFF state, the DEEPSLEEP state is the lowest power state of
the device.
In DEEPSLEEP all internal circuitry is powered down with the exception of the always-on
memory which can be used to hold the device configuration for restoration on wakeup
Once in DEEPSLEEP the DW1000 remains there until the occurrence of a wakeup event.
This can be either:
1. the SPICSn line pulled low or
2. the WAKEUP line driven high
for the duration quoted in the DW1000 data sheet (nominally 500 μs).
It is also recommended to use the SLP2INIT or CPLOCK event status bits (in Register file:
0x0F – System Event Status Register ) to drive the IRQ interrupt output line high to
confirm the wake-up.
Once the DW1000 has detected a wakeup event it progresses into the WAKEUP state.
While in DEEPSLEEP power should not be applied to GPIO, SPICLK or SPIMISO pins as this
will cause an increase in leakage current.
TX state
In the TX state the DW1000 actively transmits a frame containing the contents of the
transmit buffer on the configured RF channel with the configured transmit parameters
(PRF, data rate, preamble code etc.)
Once the frame transmission is complete the DW1000 may enter one of three modes
depending on the programmed configuration.
After the frame transmission is complete the DW1000 will return to the IDLE state
unless the ATXSLP bit is set (in Sub-Register 0x36:04 – PMSC_CTRL1 ) in which case the
DW1000 will enter the SLEEP or DEEPSLEEP state automatically, (as long as no host
interrupts are pending).
Note that it is not possible to be in the TX and RX states simultaneously – the DW1000 is
a half-duplex transceiver device.
RX state
In the RX state, the DW1000 receiver is active, either hunting for preamble or (once it
has detected preamble) actively receiving preamble searching for SFD, and subsequently
receiving the PHR, decoding it and receiving the data part of the frame. In the
RX state,
the RF synthesiser and all RX blocks are active. After an event that ends the reception,
(either a good frame RX, or some error or timeout event that aborts reception) the
DW1000 will return to the
IDLE state unless the ARXSLP bit is set (in Sub-Register
0x36:04 – PMSC_CTRL1 ) in which case the DW1000 will enter the SLEEP or DEEPSLEEP
state automatically (as long as no host interrupts are pending).
Note that it is not possible to be in the RX and TX states simultaneously – the DW1000 is
a half-duplex transceiver device.
SNOOZE
The SNOOZE state is similar to the INIT state except that a counter is running to cause
the DW1000 to automatically go to the RX state (via INIT and IDLE ) when the counter
expires. The snooze count times are in units of the raw 19.2 MHz XTI clock rate, (since