GSM/GPRS Module
M85 Hardware Design
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RTS
CTS
RTS
CTS
GND
RXD
TXD
TXD
RXD
GND
Module (DCE)
Host (DTE)
Controller
Figure 20: 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:
IO Connector
TXD
RXD
GND
PWRKEY
Module (DCE)
UART port
TXD
RXD
GND
PWRKEY
Figure 21: Reference Design for Firmware Upgrade
The firmware of module might need to be upgraded due to certain reasons. It is recommended to reserve
these pins in the host board for firmware upgrade. For detailed design, please refer to the
document [11]
.
NOTE
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