Specifications

FAA20 Embedded NEXCOM Vocoder
Board Manual
This manual has been prepared for the Federal Aviation Administration.
FA100-00107 (March 2004) – Rev 1.0.0 Page 8
SIGNAL PIN DIR DESCRIPTION
DDAT A21 O
rsvd
DTMF Data Output (active high): This signal is not used
by the FAA20. During power up, it is initialized to the low
(inactive) state.
GO C24 I GO Mode (active high): The GO signal must be active to
place the encoder in voice mode. The FAA20 samples
this signal on the falling edge of DCLK when the DFS bit
is also set. When this signal is inactive, the encoder
resets (internally) and outputs silence frames. A built-in
pull-up resister enables this signal when the pin is left
unconnected.
Note: This bit is not functional in TEST mode.
TMTX B32 O Truncated Timing Status (active high). When set, the
FAA20 is in truncated timing mode.
Note: This bit is not functional in TEST mode.
TMRX B31 I Truncated Timing Control (active low). When low, causes
the FAA20 to enter truncated timing mode.
Note: This bit is not functional in TEST mode.
X00
X01
X02
X03
C32
A24
C25
A25
I/O
rsvd
Expansion Bits . Reserved for future use.
POWER SIGNALS
VCC A1, A2,
C1, C2
P Power (positive rail): The FAA20 requires 400 mA (typ)
and 700 mA (max) at +5V ±5%.
Note: Unlike the VC20, the FAA20 does not require an
analog circuit voltage rail.
GND A3, A8,
A13, A20,
A26, A31,
A32, C3,
C8, C13,
C20, C26,
C31, C32
P Power (ground rail): Connect to ground.
* Notes: RW = Read/Write, RO = Read Only, SWC = Software Controlled, RSVD = Reserved, CL =
Clock Latched, and rsvd = reserved for future use. All unlisted pins are not connected.