4117047
Rev 2.2
December 18, 2015
33
Product Technical Specification
Design Guidelines
Figure 13. Power OFF Sequence for PWR_ON_N, VGPIO
Note:
PWR_ON_N is internally pulled up by 200k
Ω
to 1.8V.
Caution:
Ensure that no external pull-ups are applied on IO pins while the module is OFF.
3.3. Emergency Power OFF
If required, the module can be switched off by controlling the RESET_IN_N pin (pin 11). This must
only be used in emergency situations if the system freezes (not responding to AT commands).
To perform an emergency power off, a low level pulse must be sent on the RESET_IN_N pin for 10ms
while the PWR_ON signal is inactive (high level). This action will immediately shut the HL8518,
HL8528 and HL8529 modules down and the registers of the CPU and RAM memory will be reset for
the next power on.
3.4. Sleep Mode Management
3.4.1.
Using UART
AT command
AT+KSLEEP
enables sleep mode configuration.
AT+KSLEEP=0
:
The module is active when DTR signal is active (low electrical level).
When DTR is deactivated (high electrical level), the module will enter sleep mode after a
while.
On DTR activation (low electrical level), the module wakes up.
AT+KSLEEP=1
:
The module determines when it enters sleep mode (when no more tasks are running).
“0x00” character on the serial link wakes the module up.
AT+KSLEEP=2
:
The module never enters sleep mode.
3.4.2.
Using USB
Use
AT+KSLEEP=1
to allow the module to automatically enter sleep mode while the USB interface is
in use.
