User's Manual
HC864-AUTO Hardware User Guide
1vv0300946 Rev.4 – 2012-12-27
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights
Reserved. Page 43 of 77
The levels for HC864-AUTO UART are the CMOS levels:
Absolute Maximum Ratings -Not Functional
HC864-AUTO
Parameter
Min Max
Input level on any
digital pin when on
-0.3V +3.0V
Input voltage on
analog pins when on
-0.3V +2.7 V
Operating Range - Interface levels
HC864-AUTO
Level
Min Max
Input high level 2.0V 2.6 V
Input low level -0.3V 0.6V
Output high level 2.2V 2.6V
Output low level 0V 0.4V
The signals of the HC864-AUTO serial port are:
RS232
Pin
Number
Signal
HC864-AUTO
Pad Number
Name Usage
1
DCD -
dcd_uart
32 Data Carrier Detect
Output from the HC864-AUTO that indicates the
carrier presence
2
RXD -
Tx_uart
26
Transmit line *see
Note
Output transmit line of the HC864-AUTO UART
3
TXD -
Rx_uart
25
Receive line *see
Note
Input receive of the HC864-AUTO UART
4
DTR -
dtr_uart
29
Data Terminal
Ready
Input to the HC864-AUTO that controls the DTE
READY condition
5 GND 5,6,7 Ground ground
6
DSR -
dsr_uart
27 Data Set Ready
Output from the HC864-AUTO that indicates the
module is ready
7
RTS -
rts_uart
31 Request to Send
Input to the HC864-AUTO that controls the
Hardware flow control
8
CTS -
cts_uart
28 Clear to Send
Output from the HC864-AUTO that controls the
Hardware flow control
9
RI -
ri_uart
30 Ring Indicator
Output from the HC864-AUTO that indicates the
Incoming call condition
TIP:
For minimum implementation, only the TXD and RXD lines can be connected, the other lines
can be left open provided a software flow control is implemented.