CC1010-RTY1 datasheet(91/152 Pages) TI

91 / 152 page

CC1010

SWRS047

Page 91 of 152

17.6 Data Modem and Data Modes

Four different data modes are defined for

transmission and reception, programmable

through MODEM0.DATA_FORMAT. These

modes differ in data encoding, how

incoming and outgoing data is delivered

and

accepted,

and

whether

resynchronisation of the bitstream is

performed (clock regeneration) or not. The

data format should be selected before

enabling the RF Transceiver

Two of the modes, Synchronous NRZ

mode

and

Synchronous

Manchester

encoded mode, transmit or receive data

using

baudrate

specified

MODEM0.BAUDRATE. The modem does

resynchronisation of the bit stream during

reception. In the Manchester mode the

modem

also

does

the

Manchester

encoding and decoding. The NRZ and

Manchester modes accept and deliver

data either one bit or one byte at a time,

programmable

through

RFCON.BYTEMODE. In most applications

these two modes are recommended.

Data to be transmitted or data received

are stored in the RFBUF register. During

transmission or reception the need for

more data or the arrival of new data, bit by

bit or byte by byte depending on

RFCON.BYTEMODE,

signaled

generating an interrupt (EXIF.RFIF.)

Depending on whether the RF interrupt is

enabled or not (EIE.RFIE), transmission

or reception can be handled by an

interrupt service routine or be performed

by polling.

During reception when using NRZ or

Manchester mode, hardware preamble

and start of frame detection can optionally

be activated using the registers PDET and

BSYNC.

This

described

the

Synchronization and preamble detection

section on page 102.

Two other modes, Transparent mode and

UART mode, simply passes data between

the FSK modem and the RFBUF register

and UART0, respectively, allowing custom

baud rates and data encoding. When

using the UART0 in the UART mode the

pin P3.1 is not used for UART output and

can instead be used for general I/O.

Chipcon strongly recommends that the

synchronous modes be used. The other

data modes bypass the data decision

circuitry of the RF transceiver and do not

support bytemode. The Transparent mode

is only intended for testing.

17.6.1

Manchester encoding

In Manchester mode the data clock is

transmitted along with the data. A '1' is

encoded as a high frequency f1 followed

by a lower frequency f0. A '0' is encoded

as a low frequency f0 followed by a higher

frequency f1. This is illustrated in Figure

23. See the Frequency programming

section on page 106 for definitions of f0

and f1.

The Manchester code ensures that the

signal has a constant DC component,

which

necessary

some

FSK

demodulators. Using this mode also

ensures compatibility with

CC400 / CC900

designs.

The properties of the different data modes

are summarized in Table 29.

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