RFM219SW

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5.7 Operation States, Timing and Power

5.7.1 Power-Up Sequence

The chip operation starts from a valid power-on reset. It usually takes about 0.5 ms for the valid power-on reset to release. Once

the POR is released the crystal oscillator start oscillating. The time taken for the crystal oscillator to get stable is fixed at 2.5 ms in

the first power-up. After the crystal gets stable, it takes about 6.5 ms for the chip to perform the internal blocks calibrations. The

calibrations are only performed once at the beginning of one power-on cycle.

VDD

POR

Time

POR Release

<= 0.5 ms

XTAL Stablize

= 2.5 ms

Blocks Calibrations

<= 6.5 ms

Enters the SLEEP State

Ready to Work

Figure 16. Power-Up Sequence Timing

The chip enters the SLEEP mode as soon as the calibrations are done. From this point on, the MCU can then actively switch the

chip into different operating states by writing the register bits OP_SWITCH<4:0>.

5.7.2 Operating States

There are in all 6 operating states: PUP, SLEEP, STBY, TUNE, RX and EEPROM, as shown in the below table.

Table 12. RFM219SW Operation States

State

Command

Active Blocks

Optional Blocks

PUP

soft_reset

POR, XTAL

None

SLEEP

go_sleep

SPI, POR

LFOSC, Sleep Timer

STBY

go_stby

SPI, POR, XTAL, FIFO

CLKO

TUNE

go_tune

SPI, POR, XTAL, PLL, FIFO

CLKO

RX

go_rx

All

CLKO, RX Timer

EEPROM

go_eeprom

SPI, POR, XTAL

CLKO

The 6 commands used by the MCU to switch the states are simply register-writing operation. Please see OP_CTRL and

SOFTRST register description for the details. The MCU can arbitrarily switch the states, as long as it complies with the switching

time requirement and rules. For example, the MCU can directly switch the chip from SLEEP state to RX state, while it has to wait

for the time of “Xtal Stabilizing Time + 300 us + 20 us” before taking any further actions in the RX state. While switching the states

backward, the time cost is negligible. Switching to the EEPROM state is only allowed in the SLEEP state. The soft reset will pull

the device back to the PUP state and re-perform the blocks calibrations.