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CSn
SO
XOSC Stable
XOSC and voltage regulator switched on
SI
SRES
40 µs
SWRS037B – JANUARY 2006 – REVISED MARCH 2015
Figure 5-13. Power-up with SRES
NOTE
The above reset procedure is only required just after the power supply is first turned on. If
the user wants to reset the CC1150 after this, it is only necessary to issue an SRES
command strobe.
It is recommended to always send a SRES command strobe on the SPI interface after power-on even
though power-on reset is used.
5.11.2 Crystal Control
The crystal oscillator is automatically turned on when CSn goes low. It will be turned off if the SXOFF or
SPWD command strobes are issued; the state machine then goes to XOFF or SLEEP respectively. This
can only be done from IDLE state. The XOSC will be turned off when CSn is released (goes high). The
XOSC will be automatically turned on again when CSn goes low. The state machine will then go to the
IDLE state. The SO pin on the SPI interface must be pulled low before the SPI interface is ready to be
used; as described in
Crystal oscillator start-up time depends on crystal ESR and load capacitances. The electrical specification
for the crystal oscillator can be found in
.
5.11.3 Voltage Regulator Control
The voltage regulator to the digital core is controlled by the radio controller. When the chip enters the
SLEEP state, which is the state with the lowest current consumption, the voltage regulator is disabled.
This occurs after CSn is released when a SPWD command strobe has been sent on the SPI interface.
The chip is then in the SLEEP state. Setting CSn low again will turn on the regulator and crystal oscillator
and make the chip enter the IDLE state.
On the CC1150, all register values (with the exception of the MCSM0.PO_TIMEOUT field) are lost in the
SLEEP state. After the chip gets back to the IDLE state, the registers will have default (reset) contents
and must be reprogrammed over the SPI interface.
5.11.4 Active Mode
The active transmit mode is activated by the MCU by using the STX command strobe.
The frequency synthesizer must be calibrated regularly. CC1150 has one manual calibration option (using
the SCAL strobe), and three automatic calibration options, controlled by the MCSM0.FS_AUTOCAL
setting:
•
Calibrate when going from IDLE to TX (or FSTXON)
•
Calibrate when going from TX to IDLE
•
Calibrate every fourth time when going from TX to IDLE
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Detailed Description
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