GSM/GPRS Module Series
M85 Hardware Design
M85_Hardware_Design Confidential / Released 40 / 88
Three-line connection is shown as below.
TXD
RXD
GND
UART port
RTS
0R
TXD
RXD
GND
Module (DCE)
Host (DTE)
Controller
Figure 18: Reference Design for UART Port
UART Port with hardware flow control is shown as below. This connection will enhance the reliability of
the mass data communication.
RTS
CTS
RTS
CTS
GND
RXD
TXD
TXD
RXD
GND
Module (DCE)
Host (DTE)
Controller
Figure 19: Reference Design for UART Port with Hardware Flow Control
3.7.1.3. Firmware Upgrade
The TXD, RXD can be used to upgrade firmware. The PWRKEY pin must be pulled down before firmware
upgrade. The reference circuit is shown as below:
