User's Manual

GSM/GPRS/GNSS Module Series
MC20 Hardware Design
MC20_Hardware_Design Confidential / Released 44 / 95
RXD_AUX: Keep open except during firmware upgrade.
The GNSS UART Port
 In all-in-one solution:
GNSS_TXD: Send data to the GSM part.
GNSS_RXD: Receive data from the GSM part.
 In stand-alone solution:
GNSS_TXD: Send GNSS data to the COM port of peripheral.
GNSS_RXD: Receive GNSS data from the COM port of peripheral.
The logic levels are described in the following table.
Table 13: Logic Levels of the UART Interface
Table 14: Pin Definition of the UART Interfaces
Parameter Min. Max. Unit
V
IL
0 0.25×VDD_EXT V
V
IH
0.75×VDD_EXT VDD_EXT +0.2 V
V
OL
0 0.15×VDD_EXT V
V
OH
0.85×VDD_EXT VDD_EXT V
Interface Pin Name Pin No. Description
UART Port
TXD 34 Transmit data
RXD 33 Receive data
DTR 37 Data terminal ready
RI 35 Ring indication
DCD 36 Data carrier detection
CTS 38 Clear to send
RTS 39 Request to send
Debug Port DBG_RXD 30 Receive data