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WM_PRJ_Q2686_PTS_001-010
June 30, 2009
Q2686 Wireless CPU
®
3.7
Auxiliary Serial Link (UART2)
An auxiliary serial interface (UART2) is available on Q2686. This interface may
be used to connect a Bluetooth or a GPS chip controlled by an Open AT
®
Plug-
in.
UART2 interface pin description
Signal
Pin
number
I/O I/O type Reset
state
Description
Multiplexed
with
CT103 /
TXD2*
31
I
1V8
Z
Transmit serial data
GPIO14
CT104 /
RXD2*
30 O 1V8
Z
Receive serial data
GPIO15
~CT106 /
CTS2*
32 O 1V8
Z
Clear To Send
GPIO16
~CT105 /
RTS2*
33 I 1V8
Z
Request To Send
GPIO17
See Chapter 3.3, “Electrical information for digital I/O” for Open drain, 2V8 and 1V8 voltage
characteristics and Reset state definition.
* According to PC view
The Q2686 is designed to operate using all the serial interface signals. In
particular, it is recommended to use RTS and CTS for hardware flow control in
order to avoid data corruption during transmission.
The maximum baud rate of UART2 is 921 kbit/s for the firmware provided with
Open AT
®
Software Suite v2.
For use with 4-wire serial interface
•
CT103/TXD2*, CT104/RXD2*, ~CT105/RTS2*, ~CT106/CTS2*
•
The signal ~CT108-2/DTR2* must be configured at low level.
•
Other signals and their multiplexes are not available.
•
Please refer to technical appendixes in the AT commands User Guide [7]
for more information.
For use with 2-wire serial interface
•
This case is possible for connected external chip, but not recommended
(and forbidden for AT command or modem use)
•
The flow control mechanism has to be managed at the customer side.
•
CT103/TXD2*, CT104/RXD2*
•
The signals ~CT105/RTS2*, ~CT106/CTS2* are not used, you must
configure the AT command (AT+IFC=0,0 see AT commands User Guide
[7]).