EM77950 datasheet(47/102 Pages) EMC

47 / 102 page

EM77950

BB Controller

Product Specification (V1.0) 10.09.2007

• 39

(This specification is subject to change without further notice)

Baseband (BB)

8.1 BB: Standard Interface for the RFW102 Series

8.1.1 Features

Parallel interface to RFW102 modem

Serial to Parallel conversion of RFW102 interface

Input FIFO (RX_FIFO)

Output FIFO (TX_FIFO)

Preamble Correlation

Packet Address Filter (Network and unique)

CRC calculation

Working Frequencies: 6-24MHz

Power Save modes: Idle, Power-down

Inter-RFWAVES networks Carrier-sense

Discharge of the RFW-102 reference capacitor

Compensate for clock drifts between transmitting and the receiving the EM77950

up to 1000ppm. Hence, the EM77950 requires low performance crystal.

Interrupt Driver – connected to the EM77950’s internal interrupt and informs the

EM77950 about BB events.

8.1.2 Description

RFWAVES has developed a very low cost wireless modem (RFW102) for short range,

cost-sensitive applications. The modem is a physical layer element (PHY) – allowing

the transmission and reception of bits from one end to the other.

In an RFWAVES application, the MCU is in charge of the MAC layer protocol. In order

to reduce the real-time demands of the MCU handling the MAC protocol, the BB was

developed. The BB enables the MCU an easy interface to RFW102 through a parallel

interface, similar to memory access. It converts the fast serial input to 8-bit words,

which are much easier for an 8-bit MCU to work with, and requires a lower rate

oscillator. It buffers the input through a TBD bytes FIFO, enabling the MCU to access

the BB more efficiently. Instead of reading one byte per interrupt, the MCU can read up

to 16 bytes in each interrupt. This reduces the MCU overhead in reading incoming

words, insofar as stack stuffing and pipeline emptying are concerned, in cases where

each incoming byte causes an interrupt. When using the FIFO, the MCU pays the

same overhead for all the FIFO bytes as it paid for only one byte without a FIFO.

EM77950 Datasheet(PDF) 47 Page - ELAN Microelectronics Corp