User's Manual

M80 Hardware Design
M80_HD_V1.2 - 44 -
The Debug Port
 DBG_TXD: Send data to the COM port of a debugging computer.
 DBG_RXD: Receive data from the COM port of a debugging computer.
The Auxiliary UART Port
 TXD_AUX: Send data to the RXD of DTE.
 RXD_AUX: Receive data from the TXD of DTE.
The logic levels are described in the following table.
Table 10: Logic levels of the UART interface
Parameter
Min
Max
Unit
V
IL
0
0.25×VDD_EXT
V
V
IH
0.75×VDD_EXT
VDD_EXT +0.3
V
V
OL
0.15×VDD_EXT
V
V
OH
0.85×VDD_EXT
V
Table 11: Pin definition of the UART interfaces
Interface
Name
Pin
Description
Debug Port
DBG_RXD
43
Receive data of the debug port
DBG_TXD
42
Transmit data of the debug port
UART Port
RI
46
Ring indicator
RTS
51
Request to send
CTS
48
Clear to send
RXD
50
Receive data of the UART port
TXD
49
Transmit data of the UART port
DTR
47
Data terminal ready
DCD
45
Data carrier detection
Auxiliary UART Port
RXD_AUX
41
Receive data of the Auxiliary UART
TXD_AUX
40
Transmit data of the Auxiliary UART
3.9.1. UART Port
3.9.1.1 The features of UART Port.
 Seven lines on UART interface
 Contain data lines TXD and RXD, hardware flow control lines RTS and CTS, other control
lines DTR, DCD and RI.
 Used for AT command, GPRS data, CSD FAX, etc. Multiplexing function is supported on the