Siemens TC65 Specifications download pdf (Page 111)

TC65 Hardware Interface Description

Confidential / Released

TC65_HD_V02.000 Page 111 of 120 08.06.2006

7 Sample Application

Figure 47 shows a typical example of how to integrate a TC65 module with a Java

application. Usage of the various host interfaces depends on the desired features of the

application.

Audio interface 1 demonstrates the balanced connection of microphone and earpiece. This

solution is particularly well suited for internal transducers. Audio interface 2 uses an

unbalanced microphone and earpiece connection typically found in headset applications.

The charging circuit is optimized for the charging stages (trickle charging and software

controlled charging) as well as the battery and charger specifications described in Chapter

3.5.

The PWR_IND line is an open collector that needs an external pull-up resistor which

connects to the voltage supply VCC µC of the microcontroller. Low state of the open

collector pulls the PWR_IND signal low and indicates that the TC65 module is active, high

level notifies the Power-down mode.

If the module is in Power-down mode avoid current flowing from any other source into the

module circuit, for example reverse current from high state external control lines. Therefore,

the controlling application must be designed to prevent reverse flow.

If the I

C bus is active the two lines I2CCLK and I2DAT are locked for use as SPI lines. Vice

versa, the activation of the SPI locks both lines for I

C. Settings for either interface are made

by using the AT^SSPI command.

The internal pull-up resistors (Rp) of the I

C interface can be connected to an external power

supply or to the VEXT line of TC65. The advantage of using VEXT is that when the module

enters the Power-down mode, the I

CI interface is shut down as well. If you prefer to connect

the resistors to an external power supply, take care that the interface is shut down when the

PWR_IND signal goes high in Power-down mode.

The interfaces ASC0, ASC1 and USB have different functions depending on whether or not

Java is running. Without Java, all of them are used as AT interfaces. When a Java

application is started, ASC0 and ASC1 can be used for CommConnection or/and

System.out, and the USB lines can be used for debugging or System.out.

The EMC measures are best practice recommendations. In fact, an adequate EMC strategy

for an individual application is very much determined by the overall layout and, especially,

the position of components. For example, mounting the internal acoustic transducers directly

on the PCB eliminates the need to use the ferrite beads shown in the sample schematic.

However, when connecting cables to the module’s interfaces it is strongly recommended to

add appropriate ferrite beads for reducing RF radiation.

Disclaimer

No warranty, either stated or implied, is provided on the sample schematic diagram shown in

Figure 47 and the information detailed in this chapter. As functionality and compliance with

national regulations depend to a great amount on the used electronic components and the

individual application layout manufacturers are required to ensure adequate design and

operating safeguards for their products using TC65 modules.

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