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RF68

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4.3. Application Mode: Power & Go

The default ‘Power & Go’ application mode sees the RF68 configured as detailed in Table 6. By changing the logical

state of the CTRL pin at Power-up or Reset, two distinct configuration modes can be selected. The Power & Go application

modes hence permit microcontroller-less operation.

Table 6

Configuration in Power & Go Mode

CTRL Pin

Configuration

Mode

‘Low’

FSK 868.3 MHz, +10 dBm, Fdev=+/-19.2 kHz

Power&Go 1

‘High’

OOK 433.92 MHz, +10 dBm

Power&Go 2

4.4. Application Mode: Advanced

4.4.1. Advanced Mode: Configuration

As described on Figure 4, Advanced mode is entered when accessing the Two Wire Interface (TWI) bus of the RF68.

Upon communication to the register at up to 10 MHz of clocking speed, complete flexibility on the use of the chip is

obtained.

Once all register settings are selected (see registers detailed description in section [5]), the RF68 can be used either in

Automatic mode by simply toggling the DATA pin, or in Forced Transmit mode to optimize timings for instance.

4.4.2. Frequency Hopping Spread Spectrum

Frequency hopping is supported in Advanced mode. After sending the data stream in the first channel, the user can send

a Frequency change instruction containing the new channel frequency. The circuit will automatically ramp down the PA,

lock the PLL to the new frequency, and turn the Power Amplifier back on. The user can then send his packet data on the

new channel. Timings are detailed hereafter:

t < TOFFT

(2 or 20 ms)

TWI

instruction

t < TOFFT

(2 or 20 ms)

DATA

Frequency change

CTRL

Frequency change

RFOUT

5th falling

edge on CTRL

24th falling

edge on CTRL

Tx Channel A

Tx Channel B

Figure 6. Frequency Hopping Description

Notes - During any TWI access, the input of the modulator is inhibited

- The time between two Frequency change instructions shall be greater than TS_HOPi

- FHSS modulation, as described under FCC part 15.247, is supported by the RF68; also note that the large

Frequency Deviation settings available on the RF68 make it suitable for “Digitally Modulated Systems”, as

described under FCC Part 15.247 (a)(2)