Specifications

L506 Hardware Design
Copyright© Shanghai Mobiletek Communication Ltd 36
junction capacitance value <5pf, otherwise the larger junction capacitance will cause waveform
distortion, the impact of bus communication. Differential impedance of differential data line in 90ohm
+ 10%. In your application must add a 47Kohm resistor between USB_VBUS to ground.
Figure 3-11 USB application
3.8 UART Interface
3.8.1 Pin description
L506 module provides a flexible 7-wire UART (universal asynchronous serial transmission)
interface.UART as a full asynchronous communication interface, Support the standard modem
handshake signal control, Comply with the RS - 232 interface protocols. And also support four wire
serial bus interface or the 2-wire serial bus interface mode, and the module can be through the UART
interface for serial communication with the outside (DET) and the AT command input, etc.L506
module is a DCE (Data Communication Equipment) and client PC is a DTE (Data Terminal
Equipment).AT commands are entered and serial communication is performed through UART
interface. The pin signal is defined as shown in below table.
Table 3-14 UART pin definition
Pin No.
Pin
I/O type
Descriptions
71
UART_TX
DO
UART data transmission
68
UART_RX
DI
UART data receive
69
UART_RI
DO
Ring Indicator.
66
UART_RTS
DO
UARTDET request to send
72
UART_DTR
DI
DTE get ready.
67
UART_CTS
DI
UART Clear to Send.
70
UART_DCD
DO
UART Carrier detects.
L506(DCE)
HOST(PC)
USB_DP
USB_DM
VBUS
GND
USB_ID
VBUS
USB_DP
USB_DM
GND
0R
47K
0R