ST25R3911B datasheet(34/116 Pages) STMICROELECTRONICS

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0º ≤ φ ≤ 30º: result = 255 (decimal)

•

30º < φ < 150º: angle (in º) = 30 + [(255 - u_angle) / 255) * 120]

•

150º ≤ φ ≤ 180º: result = 0 (decimal)

Duration time: 25 μs max.

This command is accepted in case en (bit 7 of the Operation control register) is set and Xtal oscillator frequency is

stable.

Direct command chaining is not possible.

IRQ due to termination of direct command is produced after command execution is terminated.

Clear RSSI

The receiver automatically clears the RSSI bits in the RSSI 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 RSSI display register, and the RSSI

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

This command is accepted in case en (bit 7 of the Operation control register) is set and Xtal oscillator frequency is

stable.

Direct command chaining is possible.

IRQ due to termination of direct command is not produced.

Transparent mode

Enters in the Transparent mode. The Transparent mode is entered on the rising edge of signal /SS and is

maintained as long as signal /SS is kept high.

This command is accepted when en (bit 7 of the Operation control register) is set and Xtal oscillator frequency is

stable.

Calibrate capacitive sensor

This command calibrates the capacitive sensor. See Section 1.1.5 Capacitive sensor for more details.

Duration time: 3 ms max.

This command is executed in case capacitive sensor automatic calibration mode is set (all bits cs_mcal in the

Capacitive sensor control register are set to 0). In order to avoid interference with Xtal oscillator and reader

magnetic field, it is strongly recommended to use this command in Power-down mode only.

Direct command chaining is not possible.

IRQ due to termination of direct command is produced after command execution is terminated.

Measure capacitance

This command performs the capacitance measurement. See Section 1.1.5 Capacitive sensor for more details.

Duration time: 250 μs max.

In order to avoid interference with Xtal oscillator and reader magnetic field it is strongly recommended to use this

command in Power-down mode only.

Direct command chaining is not possible.

IRQ due to termination of direct command is produced after command execution is terminated.

Measure power supply

This command performs the power supply measurement. Configuration bits mpsv1 and mpsv0 of the Regulator

voltage control register define which power supply is measured (VDD,VSP_A, VSP_D and VSP_RF can be

measured). Result of measurement is stored in the A/D converter output register.

During the measurement the selected supply input is connected to a 1/3 resistive divider, whose output is

multiplexed to A/D converter in absolute mode. Due to division by 3, one LSB represents 23.438 mV.

Duration time: 25 μs max.

This command is accepted in case en (bit 7 of the Operation control register) is set and Xtal oscillator frequency is

stable.

ST25R3911B

Application information

DS11793 - Rev 6

page 34/116

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