SPIRIT1 datasheet(47/94 Pages) STMICROELECTRONICS

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SPIRIT1

Transmission and reception

Doc ID 022758 Rev 3

47/94

If the center frequency is above the frequency threshold for that frequency band, VCO_H

must be selected by setting the bit 1 VCO_ H _SEL field in the SYNTH_CONFIG register.

The user must make sure that actual frequency programming is inside the specified

frequency range. The accuracy of the offset is about 99 Hz for the 26 MHz reference and

about 198 Hz for the 52 MHz reference.

9.3

RX timeout management

In SPIRIT1, the RX state is specifically time monitored in order to minimize power

consumption. This is done by a RX timeout approach, which aborts the reception after TRX

timeout expiration. The timer used to control RX timeout is controlled by the registers

RX_TIMEOUT_PRESCALER and RX_TIMEOUT_COUNTER . However, to avoid the

reception to be interrupted during a valid packet, a number of options to stop the timeout

timer are available for the user. They are based on the received signal quality indicators (see

Section 9.7 for a full description of them):

●

CS valid

●

SQI valid

●

PQI valid

More specifically, both 'AND' or 'OR' boolean relationships among any of them can be

configured. This is done using the selection bit RX_TIMEOUT_AND_OR_SELECT in

PCKT_FLT_OPTIONS register. To choose which of the quality indicators should be taken

into account in the AND/OR Boolean relationship, the user should use the mask bits

available in the PROTOCOL[2] register.

The full true-table including any logical AND/OR among such conditions is reported in

Table 26.

Table 25.

Frequency threshold

Frequency threshold for each band (MHz)(1)

By default, the VCO_H is selected.

Very low band

Low band

Middle band

High band

161281250

322562500

430083334

860166667

Table 26.

RX timeout stop condition configuration

RX_TIMEOUT_

AND_OR_SELECT

CS_TIMEOUT_MASK

SQI_TIMEOUT

_MASK

PQI_TIMEOUT_M

ASK

Description

No timeout stop

Timeout always stopped

(default)

RSSI above threshold

SQI above threshold

PQI above threshold

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