ST25R3910 datasheet(27/65 Pages) STMICROELECTRONICS

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ST25R3910

Functional overview

is reduced by one step (120 mV in case of 5 V supply and 100 mV in case of 3.3 V supply)

and measurement is done after another 300 μs. The procedure is repeated until VSP_RF

drops at least 250 mV below VDD, or until the minimum regulated voltage (3.9 V in case of

5 V supply and 2.4 V in case of 3.3 V supply) is reached.

Duration time: 5 ms max.

This command is accepted in any mode where the oscillator and regulators are running.

This command is not accepted when the external definition of the regulated voltage is

selected in the Regulated Voltage Definition Register (bit reg_s is set to H).

Calibrate Modulation Depth

Starts a sequence that activates the transmission, measures the modulation depth and

adapts it to comply with the modulation depth specified in the Modulation Depth Definition

about setting the AM modulation depth and running this command.

Duration time: 10 ms max.

This command is accepted in any mode where the oscillator and regulators are running.

Calibrate Antenna

Sending this command starts a sequence that adjusts the parallel capacitances connected

to TRIMx_y pins so that the antenna LC tank is in resonance. See Section 1.2.15: Antenna

tuning for details.

Duration time: 400 μs max.

This command is accepted in any mode where the oscillator and regulators are running.

Check Antenna Resonance

This command measures the antenna LC tank resonance to determine whether a

calibration is needed. See Check Antenna Resonance for details.

Duration time: 42μs max.

This command is accepted in any mode where the oscillator and regulators are running.

Clear RSSI

The receiver automatically clears the RSSI bits in the Receiver State Display Register and

starts to measure the RSSI of the received signal when the signal rx_on is asserted. Since

the RSSI bits store peak value (peak-hold type) the variations of the receiver input signal will

not be followed (this may happen in case of long messages or test procedures). The direct

command Clear RSSI clears the RSSI bits in the Receiver State Display Register, and the

RSSI measurement is restarted (in case, of course, rx_on is still high).

Transparent Mode

Enters in the Transparent mode. The Transparent mode is entered on the falling edge of

signal SEN and is maintained as long as signal SEN is kept low.

This command is accepted only when the Transmitter and the Receiver are operating.

ST25R3910 Datasheet(PDF) 27 Page - STMicroelectronics