RFM67W Datasheet, PDF (10/37 Pages) List of Unclassifed Manufacturers – ISM TRANSMITTER MODULE

RFM 67W
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
Modes
Operating
MODE(2:0)
000
001
010
011
Selected Mode
Sleep mode
Stand-by mode
FS mode
Transmit mode
RC Osc
Optional
Optional
Optional
Optional
Enabled Blocks
SPI
Xtal Osc Freq. Synth.
PA
x
x
x
x
x
x
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
stand- alone application mode the RFM67W can download its configuration from an external SPI E²PROM. Moreover, in
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
register settings and data payload from an SPI E²PROM. Four debounced GPIO inputs are available in stand alone mode,
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
E²PROM.
The RFM67W can accommodate SPI E²PROM sizes up to 8 kbit and uses industry standard SPI commands. For a full
description of E²PROM use with RFM67W and the associated application circuits, please see Section 6.1. The
application circuit for stand-alone operation is shown in Figure 3, note that both matching and L_M are band specific
whilst C_TX is application specific.
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