EM77950
BB Controller
Name
DATA [0-7]
RD_n
Type
Description
This bus comprises of eight TRI-STATE input/output lines. The bus
provides bidirectional communication between the system and the
MCU. Data, control words, and status information are transferred
via the DATA [0-7] data bus.
I/O
When RD_n is low while the system is enabled, BB outputs one of its
internal register values to DATA[0-7] according to RAM_ADDR[0-6].
I
I
I
When WR_n is low while the system is enabled, BB enables writing
to its internal registers. The register is determined by RAM_ADDR
[0-6] and the value DATA[0-7].
WR_n
RAM_ADDR[0-6]
These four input signals determine the register to which the MCU
writes to or reads from.
Chip select input pin. When CS_n is low, the chip is selected; when
high, the chip is disabled. This pin overrides all pins excluding RST.
This enables communication between BB and the MCU.
CS_n
I
This pin functions as wakeup pin for power-down and idle modes.
Interrupt driver pins.
TX_AE;
TX_EMPTY;
RX_AF;
CS;
LOCK_IN;
LOCK_OUT
This pin goes high whenever any of the interrupt sources has an
active high condition and is enabled via the IER. The purpose of this
pin is to notify the MCU through its external interrupt pin that an
event (such as empty TX_FIFO) has occurred.
O
Goes low when IER register is read.
Chip’s reset pin.
When this pin is set high, all registers and FIFOs are cleared to their
initial values. All transceiver traffic is disabled and aborted. Reset is
asynchronous to system clock.
RST
I
After power-up, a pulse in RST input should be applied (by POR).
SHDWN
I
Shut Down BB
This output pin controls the RFW102 working/shutdown mode. Its
values are determined by SCR4(1).
RF_ACTIVE
O
Serial input or output according to TX_RX mode.
It functions as serial interface for the RFW-102 (RFWAVES
modem).
SERIAL_IO
I/O
When SERIAL_IO is input, it is a Schmitt-trigger input.
This pin controls RFW-102 operation mode. It should be connected
to RFW-102 RX_TX input pin.
When RX_TX is low, RFW-102 is in receiving mode.
When RX_TX is high, RFW-102 is in transmitting mode.
RX_TX
O
In most cases RX_TX output pin is determined by SCR2(0) register.
SCR3(7) and the capacitor discharge mechanism affects this pin.
RF_CLK
I
Clock for RF operation
Product Specification (V1.0) 10.09.2007
(This specification is subject to change without further notice)
• 41
ELAN [ ELAN MICROELECTRONICS CORP ]
