SWRS045F January 2006 – November 2018 CC1021
PRODUCTION DATA.
The CC1021 device has a built-in automatic power-up sequencing state machine. By setting the CC1021 device into this mode, the receiver can be powered-up automatically by a wake-up signal and will then check for a carrier signal (carrier sense). If carrier sense is not detected, it returns to power-down mode. A flow chart for automatic power-up sequencing is shown in Figure 5-18.
The automatic power-up sequencing mode is selected when PD_MODE[1:0] = 11 in the MAIN register. When the automatic power-up sequencing mode is selected, the functionality of the MAIN register is changed and used to control the sequencing.
By setting SEQ_PD = 1 in the MAIN register, the CC1021 device is set in power down mode. If SEQ_PSEL = 1 in the SEQUENCING register the automatic power-up sequence is initiated by a negative transition on the PSEL pin.
If SEQ_PSEL = 0 in the SEQUENCING register, then the automatic power-up sequence is initiated by a negative transition on the DIO pin (as long as SEP_DI_DO = 1 in the INTERFACE register).
Sequence timing is controlled through RX_WAIT[2:0] and CS_WAIT[3:0] in the SEQUENCING register.
VCO and PLL calibration can also be done automatically as a part of the sequence. This is controlled through SEQ_CAL[1:0] in the MAIN register. Calibration can be done every time, every 16th sequence, every 256th sequence, or never. See the register description for details. A description of when to do, and how the VCO and PLL self-calibration is done, is given in Section 5.12.2.