SPIRIT1QTR Datasheet, PDF (35/101 Pages) List of Unclassifed Manufacturers – Low data rate, low power sub-1GHZ transceiver

SPIRIT1
Operating modes
7.3.1
LDCR is controlled essentially by the wake-up period (T_WU), which periodically wakes up
the SPIRIT1 to perform a transmission or a reception.
In reception mode, it is also relevant to set up the RX timeout in order to minimize the
amount of time the SPIRIT1 waits for a packet during T_WU.
When setting T_WU, care should be taken when considering the analog settling time which is
required before the radio becomes fully operative for transmission or reception (T_IDLE in
Figure 7).
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Figure 7. LDCR mode timing
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The T_IDLE time can be longer than the minimum required to get analog circuits settling, and
this causes power waste. In order to minimize T_IDLE, the SPIRIT1 supports the runtime
phasing of the internal wake-up timer, as follows:
• The value of the wake-up timer can be reloaded during runtime using the
LDCR_RELOAD command with the values written in the
LDCR_RELOAD_PRESCALER/COUNTER registers. In doing so, the counting can be
delayed or anticipated
• Alternatively, the wake-up timer can be automatically reloaded at the time the SYNC is
received. This option must be enabled on the PROTOCOL register and it is available
only for LDC mode in reception.
The RC oscillator must be calibrated correctly before the LDC mode can be used. Also the
manual calibration setting is recommended to avoid delay during this mode.
If the some bits of the IRQ_MASK register are set, the IRQ_STATUS register must be read
to allow the access to the SLEEP state after a reception or transmission phase.
LDC mode with automatically acknowledgement.
The LDC mode can be used together with the automatic acknowledgement (STack packet
format configured). In this case during a single LDC cycle both the operations of reception
and transmission are performed.
If the SPIRIT1 is used as transmitter and the bitfield NACK_TX is RESET (packet's field
NO_ACK = 0), at the end of the transmission phase the SPIRIT1 will go automatically in
reception phase waiting for an ACK packet. At the end of the reception phase it will go in
SLEEP state until the WUT expires.
If the SPIRIT1 is used as receiver with the bitfield AUTO_ACK set and it receives a packet
with the NO_ACK field reset, then the transmission of the ACK packet is automatically
performed. At the end the SPIRIT1 will go in SLEEP until the WUT expires.
DocID022758 Rev 5
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