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RFM 67W

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4. Working Modes of the RFM67W

4.1. Operating Modes

The four operating modes of the RFM67W are shown in Table 6. Each of these may be selected via the SPI bus by

writing the corresponding bits to Mode(2:0). A key feature of the RFM67W is that the transition from one operating mode to

the next is automatically optimized. For example, if the transmit operating mode is selected whilst in sleep operating mode

then, in a pre-defined time-optimized sequence, each of the intermediate modes is engaged sequentially without the need

to issue any further SPI commands. For more information on timing and optimization please see Section 7.4.

Table 6

RFM67W

Operating

Modes

Enabled Blocks

MODE(2:0)

Selected Mode

RC Osc

SPI

Xtal Osc

Freq. Synth.

PA

000

Sleep mode

Optional

x

001

Stand-by mode

Optional

x

x

010

FS mode

Optional

x

x

x

011

Transmit mode

Optional

x

x

x

x

4.2. Application Modes

The RFM67W has two application modes, selected by applying an external logical level to the E2_MODE input. The first,

MCU mode (E2_Mode= ‘0’), configures the RFM67W as an SPI slave. This permits the configuration of the circuit by an

external microprocessor via the SPI interface of the RFM67W and the data to be applied via the DATA input (pin 13).

The second application mode, stand-alone mode (E2_Mode = 0), sees the RFM67W configured as SPI master. In the

response to an input on the GPIO pins, a specific configuration can be programmed and a payload transmitted.

Note that this mode selection process is performed at start up (or POR) of the circuit. Thus the hardware mode cannot be

dynamically changed without resetting the chip. This may be achieved either by power down or by issuing an active high

POR signal to the Reset input. For reset signal timing please see the diagram of Figure 13 and accompanying

description.

4.2.1. Stand Alone Mode

In stand alone mode (E2_Mode = ‘1’) the RFM67W will operate as a stand-alone SPI master which can download both

in this application mode the RFM67W remains in sleep operating mode until either a single or combination of button

presses are detected. RFM67W can then be dynamically reconfigured and / or transmit a data sequence stored within the