Host Interface Signals - Honeywell IS4921 Integration Manual

Host Interface Signals

The host interface signals are described in the table below.
Pin# TTL RS232
1 232INV
2 V
in
3 GND
4 (n)RxD
5 (n)TxD
6 (n)CTS
7 (n)RTS
8 PWRDWN
9 nBEEPER
10 nGoodRead
11 nWAKE
12 nTrig
USB
Input: TTL RS232 polarity control with 32k ohm pull-up.
NC
V Power: Supply voltage input (3V to 5.5V)
in
GND Ground: Power and signal ground.
Input: TTL Level RS232 Receive data input, weak pull up to V
D-
Bidirectional: USB D- Signal
Output: TTL Level RS232 transmits data. Polarity Determined
<reserved>
Input: TTL level Clear to Send, weak pull up to V
D+
Bidirectional: USB D+ signal
Output: TTL level RS232 Request to Send. Polarity
<reserved>
Output: Open drain, 100K pull up to V
PWRDWN
Output: Open drain, 100K pull up to V
nBEEPER
Output: Open drain, 100K pull up to V
nGoodRead
Input: Weak pull up to V
nWake
Input: Weak pull up to V
nTrig
Description
Connect to ground for UART to UART signal polarity.
Pull up to Vin for standard TTL RS232 polarity.
Polarity determined by Pin1
by Pin 1
configurable via software
configurable via software
that the IS4920 is in Power Down Mode.
capable of sinking current. PWM controlled signal can
be used to drive an external beeper.
sinking current of a Good Read LED circuit.
; active low, the signal can be used to
in
bring the engine out of Power Down (TTL RS232 version
only) or Sleep Mode (TTL RS232 and USB versions).
; active low, the signal can be used as
in
a trigger input to activate the IS4920.
. Polarity
in
; active high indicates
in
; active low signal
in
; active low signal for
in
.
in
17