GMSK Modem Data Pump
Page 4 of 37
MX909A PRELIMINARY INFORMATION
2 Signal List
Pin No
1
Signal
Type
Description
IRQ
output
This pin is a ‘wire-ORable' output for connection to the host
µ
C's Interrupt
Request input. When active, this output has a low impedance pull down
to V
SS
. It has a high impedance when inactive.
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
D7
D6
D5
D4
D3
D2
D1
D0
RD
WR
BUS
BUS
BUS
BUS
BUS
BUS
BUS
BUS
input
input
power
input
input
input
output
input
output
output
output
output
input
output
power
Read. An active low logic level input used to control the reading of data
from the modem into the host
µ
C.
Write. An active low logic level input used to control the writing of data
into the modem from the host
µ
C.
Negative supply. (ground).
Chip Select. An active low logic level input to the modem. It is used to
enable a data read or write operation.
Logic level modem register select input.
Logic level modem register select input.
Output of the on-chip oscillator.
Input to the on-chip oscillator, for an external CLOCK or XTAL circuit.
Connects to the Rx level measurement circuitry. Should be capacitive
coupled to V
SS
.
Connects to the Rx level measurement circuitry. Should be capacitive
coupled to V
SS.
Tx output signal from the modem.
A bias line for the internal circuitry, held at V
DD
/2. This pin must be
bypassed to V
SS
by a capacitor mounted close to the device pins.
Input to the Rx input amplifier.
The output of the Rx input amplifier.
Positive supply. Voltage levels are dependent upon this supply. This pin
should be bypassed to V
SS
by a capacitor mounted close to the device
pins.
Pins 2-9 (D7 - D0) are 8-bit, bi-directional, 3-state
µ
C interface data lines
V
SS
CS
A0
A1
XTAL
XTAL/CLOCK
DOC 2
DOC 1
TXOUT
V
BIAS
RXIN
RXAMPOUT
V
DD
¤
2001 MX-COM, Inc.
www.mxcom.com Tel: 800 638 5577 336 744 5050 Fax: 336 744 5054
Doc. # 20480134.005
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
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