CC1021-RTR1 datasheet(25/92 Pages) TI

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CC1021

SWRS045

Page 25 of 91

9.2.

Signal Interface

The CC1021 can be used with NRZ (Non-

Return-to-Zero) data or Manchester (also

known as bi-phase-level) encoded data.

CC1021 can also synchronize the data from

the demodulator and provide the data

clock at DCLK. The data format is

controlled by the DATA_FORMAT[1:0] bits

in the MODEM register.

CC1021 can be configured for three

different data formats:

Synchronous NRZ mode

In transmit mode CC1021 provides the data

clock at DCLK and DIO is used as data

input. Data is clocked into CC1021 at the

rising edge of DCLK. The data is

modulated at RF without encoding.

In receive mode CC1021 performs the

synchronization and provides received

data clock at DCLK and data at DIO. The

data should be clocked into the interfacing

circuit at the rising edge of DCLK. See

Figure 9.

Synchronous

Manchester

encoded

mode

In transmit mode CC1021 provides the data

clock at DCLK and DIO is used as data

input. Data is clocked into CC1021 at the

rising edge of DCLK and should be in NRZ

format. The data is modulated at RF with

Manchester code. The encoding is done

by CC1021. In this mode the effective bit

rate is half the baud rate due to the

coding. As an example, 19.2 kBaud

Manchester encoded data corresponds to

9.6 kbps.

In receive mode CC102 performs the

synchronization and provides received

data clock at DCLK and data at DIO.

CC1021 performs the decoding and NRZ

data is presented at DIO. The data should

be clocked into the interfacing circuit at the

rising edge of DCLK. See Figure 10.

In synchronous NRZ or Manchester mode

the DCLK signal runs continuously both in

RX and TX unless the DCLK signal is

gated with the carrier sense signal or the

PLL lock signal. Refer to section 21 for

more details.

If SEP_DI_DO = 0 in the INTERFACE

receive mode and data input in transmit

mode.

As an option, the data output can be made

available at a separate pin. This is done

by setting SEP_DI_DO = 1 in the

INTERFACE register. Then, the LOCK pin

will be used as data output in synchronous

mode, overriding other use of the LOCK

pin.

Transparent

Asynchronous

UART

mode

In transmit mode DIO is used as data

input. The data is modulated at RF without

synchronization or encoding.

In receive mode the raw data signal from

the demodulator is sent to the output

(DIO). No synchronization or decoding of

the signal is done in CC1021 and should be

done by the interfacing circuit.

If SEP_DI_DO = 0 in the INTERFACE

receive mode and data input in transmit

mode. The DCLK pin is not active and can

be set to a high or low level by

DATA_FORMAT[0].

If SEP_DI_DO = 1 in the INTERFACE

receive mode and the DIO pin is the data

input in transmit mode. In TX mode the

DCLK pin is not active and can be set to a

high or low level by DATA_FORMAT[0].

See Figure 11.

Manchester encoding and decoding

In the Synchronous Manchester encoded

mode CC1021 uses Manchester coding

when modulating the data. The CC1021

also performs the data decoding and

synchronization. The Manchester code is

based on transitions; a ì0î is encoded as a

low-to-high transition, a ì1î is encoded as

a high-to-low transition. See Figure 12.

The Manchester code ensures that the

signal has a constant DC component,

which is necessary in some FSK

demodulators. Using this mode also

CC1021-RTR1 Datasheet(PDF) 25 Page - Texas Instruments

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