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page 10
User Manual | Chronos
Pin # Pin Name
Pin Type
Description
If not used
Notes
15
DTR
Digital input
Main UART DTR
input to cell module
Leave open
If not used as
DTR, this pin
can be used as
a GPIO
16
GND
n/a
GND
Must be
implemented
17
SPI_CS
Digital I/O
Standard 3-wire SPI
master or slave with
chip select control
Leave open
18
SPI_MOSI
Digital I/O
Leave open
19
SPI_MISO
Digital I/O
Leave open
20
SPI_CLK
Digital I/O
Leave open
21
GND
n/a
GND
Must be
implemented
22
CELL_LED
Digital output
Cell module status
LED
Leave open
Refer to Telit
documentation
23
CTS
Digital output
Main UART CTS
output from cell
module
Leave open
24
PWR_MON
Digital output
Cell module power
monitor
Leave open
High when cell
module is ON
25
Vcell_ref
Power input
Reference voltage
for host GPIO
Leave open
26
RTS
Digital input
Main UART RTS
input to cell module
Leave open
27
TX_AUX
Digital output
Aux UART output
from cell module
Leave open
28
RX_AUX
Digital input
Aux UART input to
cell module
Leave open
29
DAC
Analog output
Leave open
Refer to Telit
documentation
30
RING
Digital output
Output from cell
module indicating
incoming call
Leave open
If not used as
RING, this pin
can be used as
a GPIO
31
ON_OFF#
Open collector input Input command for
power ON/OFF and
to wake from deep
sleep mode
Tie to GND
(see note
below)
Active Low
32
CTS1
Digital output
UART1
Leave open
33
RTS1
Digital input
UART1
Leave open
Internal 100k
pullup
34
IO2
Digital I/O
GPIO
Leave open