User's Manual

Note d‘étude / Technical document :
URD1– OTL 5696.1– 003 / 72361 Edition 02
HILO 3G Application Note
17 January 2011 - Page 16 / 38
3.2.2.4 Recommended Speaker Characteristics
Item to be inspected
Acceptance criterion
Input power: rated / max
0.1W (Rate)
Audio chain impedance
32 ohm +/- 10% at 1V 1KHz
Frequency Range
300 Hz ~ 4.0 KHz
Sensitivity (S.P.L)
>105 dB at 1KHz with IEC318 coupler
Distortion
5% max at 1K Hz, nominal input power
Figure 14: Speaker performance requirements
3.3 PWM
One PWM pin is available on the HiLo3G. It‘s a general purpose PWM which can be used for driving a vibrating device,
keypad backlight or LED. The PWM pin can be controlled through AT commands, allowing several periods and duty
cycles. More details are given in the AT commands specifications document.
User application can set PWM output:
Frequency between: 0.125Hz and 8KHz
Duty range from: 0 to 100%
3.3.1 PWM for Buzzer connection
HiLo3G module can manage PWM output to drive a buzzer. The buzzer can be used as an abnormal state alarm.
Resistors must be added to protect the buzzer. The value of these resistors depends on the buzzer and the transistor.
Normally, they can be set at 1KΩ.
Figure 15: Buzzer connection
3.3.2 Network LED
The HiLo module can manage a network LED. The LED can be connected either to one of the available GPIO or to the
PWM.
The transistors can be found a in a single package referenced as UMDXX or PUMDXX Family.
Value of resistor R depends on characteristic of chosen LED; it is used to limit the current through the diode.
Use the AT command to set the GPIO or PWM used to control the LED.