User's Manual

720 Hardware User Guide

Figure 2-20 RING indicator for incoming call

 SMS: Upon receipt of SMS, the module outputs one 35 ms low pulse.

Figure 2-21 RING indicator for SMS

2.7 Commissioning Interfaces

To facilitate software update and commissioning, reserve the commissioning interfaces.

2.7.1 FORCE_USB_BOOT

The module can enter the fastboot mode by short connecting the FORCE_USB_BOOT pin and

VDDIO_1P8V during the startup. This is the last method to troubleshoot the abnormality that the

module cannot start or operation properly.

Figure 2-22 Reference design of the fast boot interface

30 ms

35 ms