Single-Chip Low Power RF Transceiver for Narrowband Systems ...
Single-Chip Low Power RF Transceiver for Narrowband Systems ...
Single-Chip Low Power RF Transceiver for Narrowband Systems ...
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17. <strong>Power</strong> Management<br />
CC1021 offers great flexibility <strong>for</strong> power<br />
management in order to meet strict power<br />
consumption requirements in batteryoperated<br />
applications. <strong>Power</strong> down mode<br />
is controlled through the MAIN register.<br />
There are separate bits to control the RX<br />
part, the TX part, the frequency<br />
synthesizer and the crystal oscillator in the<br />
MAIN register. This individual control can<br />
be used to optimize <strong>for</strong> lowest possible<br />
current consumption in each application.<br />
Figure 30 shows a typical power-on and<br />
initializing sequence <strong>for</strong> minimum power<br />
consumption.<br />
Figure 31 shows a typical sequence <strong>for</strong><br />
activating RX and TX mode from power<br />
down mode <strong>for</strong> minimum power<br />
consumption.<br />
Note that PSEL should be tri-stated or set<br />
to a high level during power down mode in<br />
order to prevent a trickle current from<br />
flowing in the internal pull-up resistor.<br />
Application Note AN023 CC1020 MCU<br />
Interfacing is also applicable <strong>for</strong> the<br />
CC1021. This application note includes<br />
example source code and is available from<br />
the <strong>Chip</strong>con web site.<br />
<strong>Chip</strong>con recommends resetting the CC1021<br />
(by clearing the RESET_N bit in the MAIN<br />
register) when the chip is powered up<br />
initially. All registers that need to be<br />
configured should then be programmed<br />
(those which differ from their default<br />
values). Registers can be programmed<br />
freely in any order. The CC1021 should<br />
CC1021<br />
then be calibrated in both RX and TX<br />
mode. After this is completed, the CC1021<br />
is ready <strong>for</strong> use. See the detailed<br />
procedure flowcharts in Figure 29 - Figure<br />
31.<br />
With reference to Application Note AN023<br />
CC1020<br />
MCU Interfacing <strong>Chip</strong>con<br />
recommends the following sequence. Note<br />
that the CC1020 sub-routines are equally<br />
applicable <strong>for</strong> the CC1021.<br />
After power up:<br />
1) ResetCC1020<br />
2)<br />
Initialize<br />
3) WakeUpCC1020ToRX<br />
4) Calibrate<br />
5) WakeUpCC1020ToTX<br />
6) Calibrate<br />
After calibration is completed, enter TX<br />
mode (SetupCC1020TX), RX mode<br />
(SetupCC1020RX) or power down mode<br />
(SetupCC1020PD)<br />
From power-down mode to RX:<br />
1) WakeUpCC1020ToRX<br />
2) SetupCC1020RX<br />
From power-down mode to TX:<br />
1) WakeUpCC1020ToTX<br />
2) SetupCC1020TX<br />
Switching from RX to TX mode:<br />
1) SetupCC1020TX<br />
Switching from TX to RX mode:<br />
1) SetupCC1020RX<br />
SWRS045B Page 54 of 89
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