User's Manual

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Note d’étude / Technical document : URDx– OTL 5635.1– 007 / 70 230 Edition 03

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Sagem Communications document. Reproduction and disclosure prohibited

Distortion 5% max at 1K Hz, nominal input power

3.3 PWM

3.3.1 PWM for LED

The HiLo module can manage two PWM outputs to drive for example two LEDs. These LEDs can be used to

interact with the network activity.

If more than Two LEDs are required, any GPIO can be used to drive a LED. A maximum of 5 GPIOs are

available on the HiLo Module.

As LEDs are driven through PWM outputs of the HiLo, they can be configured with appropriate AT command

(for more details refer to AT command set for Sagem HiLo module specification).

User application can set for each output:

- Frequency between : 25.6KHz and 1083.3KHz

- Duty range from: 0 to 100%

3.3.2 PWM for Buzzer connection

The HiLo module can manage a dedicate PWM output to drive a buzzer. The buzzer can be used to alarm for

abnormal state.

Resistors should be added to protect the buzzer. The value of these resistors depends on the buzzer and the

transistor. Normally, they can be set as 1K ohm.

Figure 7: Buzzer connection

3.4 POWER SUPPLY

The HiLo module can be supplied by a battery or any DC/DC converter compliant with the module supply range

3.2V to 4.5V 2.2 A.

The PCB tracks must be well dimensioned to support 2.2 A maximum current. The voltage ripple caused by

resistance of power supply path (Battery internal resistance, tracks and contact resistance) could result in the

low voltage to the module.

The HiLo module does not manage the battery charging

3.4.1.1 Burst conditions

- Communication mode (worst case: 2 continuous GSM time-slot pulse):

HiLo

VBAT

PWM2