4117047
Rev 2.2
December 18, 2015
30
Product Technical Specification
Detailed Interface Specifications
2.12. POWER ON Signal (PWR_ON_N)
A low level signal has to be provided to switch the AirPrime HL8518, HL8528 and HL8529 modules
ON.
It is internally connected to the permanent 1.8V supply regulator inside the HL8518, HL8528 and
HL8529 via a pull-up resistor. Once VBAT is supplied to the module, this 1.8V supply regulator will be
enabled and so the PWR_ON_N signal is by default at high level.
The PWR_ON_N signal’s characteristics are listed in the table below.
Table 22. PWR_ON_N Electrical Characteristics
Parameter
Min
Typical
Max
Input Voltage-Low (V)
-
0.51
Input Voltage-High (V)
1.33
-
2.2
Power-up period (ms) from PWR_ON_N falling edge
2000
-
-
PWR_ON_N assertion time (ms)
25
Note:
As PWR_ON_N is internally pulled up with 200k
Ω
, a simple open collector or open drain transistor
must be used for ignition.
The software starts operating when the module is ON, but “AT Command Ready” will depend on
whether UART or USB is used.
Figure 10. PWR_ON_N Assertion Time
VGPIO is an output from the module that can be used to check if the module is active.
When VGPIO = 0V, the module is OFF.
When VGPIO = 1.8V, the module is ON (it can be in idle, communication or sleep mode)
Note:
PWR_ON_N cannot be used to power the module off. To power the module off, use AT command
AT+CPOF
.
2.13. Reset Signal (RESET_IN_N)
To reset the module, a low level pulse must be sent on the RESET_IN_N pin for 10ms. This action will
immediately restart the AirPrime HL8518, HL8528 and HL8529 modules with the PWR_ON_N signal
at low level. (If the PWR_ON_N signal is at high level, the module will be powered off.) As
RESET_IN_N is internally pulled up, a simple open collector or open drain transistor can be used to
control it.
The RESET_IN_N signal will reset the registers of the CPU and reset the RAM memory as well, for
the next power on.
