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RFM73 V2.0

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Figure 4 PRX (PRIM_RX=1) state control diagram

4.2

Power Down Mode

In power down mode RFM73 is in sleep

mode with minimal current consumption. SPI

interface is still active in this mode, and all

register values are available by SPI. Power

down mode is entered by setting the PWR_UP

bit in the CONFIG register to low.

4.3

Standby-I Mode

By setting the PWR_UP bit in the CONFIG

register to 1 and de-asserting CE to 0, the

device enters standby-I mode. Standby-I mode

is

used

to

minimize

average

current

consumption while maintaining short start-up

time. In this mode, part of the crystal oscillator

is active. This is also the mode which the

RFM73 returns to from TX or RX mode when

CE is set low.

4.4

Standby-II Mode

In standby-II mode more clock buffers are

active than in standby-I mode and much more

current is used. Standby-II occurs when CE is

held high on a PTX device with empty TX

FIFO. If a new packet is uploaded to the TX

FIFO

in

this

mode,

the

device

will

automatically enter TX mode and the packet is

transmitted.

4.5

TX Mode



PTX device (PRIM_RX=0)

The TX mode is an active mode where the

PTX device transmits a packet. To enter this

mode from power down mode, the PTX device

must

have

the PWR_UP

bit set high,

PRIM_RX bit set low, a payload in the TX

FIFO, and a high pulse on the CE for more

than 10µs.