Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 T el i t GE863-QUAD GE863-PY Hardware User Guide © Telit Communications S.p.A.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 Contents 1 OVERVIEW 5 2 HARDWARE COMMANDS 6 2.1 Turning ON the GE863-QUAD 6 2.2 Turning OFF the GE863-QUAD 2.2.1 Hardware shutdown 8 8 2.3 8 3 3.1 Hardware Unconditional Reboot POWER SUPPLY Power Supply Requirements 10 10 3.2 General Design Rules 3.2.1 Electrical design Guidelines 3.2.1.1 + 5V input Source Power Supply Design Guidelines 3.2.1.2 + 12V input Source Power Supply Design Guidelines 3.2.1.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 6.2 General Design Rules 29 6.3 Microphone Biasing 6.3.1 Balanced Microphone biasing 6.3.2 Unbalanced Microphone biasing 29 30 31 6.4 Microphone buffering 6.4.1 Buffered Balanced Mic. 6.4.2 Buffered Unbalanced (Single Ended) Mic. 32 32 34 7 37 7.1 SPEAKER Speaker lines characteristics and requirements 37 7.2 General Design rules 7.2.1 Noise Filtering 39 40 7.3 Handset earphone design 40 7.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 1 Overview The aim of this document is the description of some hardware solutions useful for developing a product with the Telit GE863-QUAD module. In this document all the basic functions of a mobile phone will be taken into account; for each one of them a proper hardware solution will be suggested and eventually the wrong solutions and common errors to be avoided will be evidenced.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 2 Hardware Commands 2.1 Turning ON the GE863-QUAD To turn on the GE863-QUAD the pad ON# must be tied low for at least 1 second and then released. The maximum current that can be drained from the ON# pad is 0,1 mA. A simple circuit to do it is: ON# R1 Q1 Power ON impulse R2 GND NOTE: don't use any pull up resistor on the ON# line, it is internally pulled up.
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Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 2.2 Turning OFF the GE863-QUAD The turning off of the device can be done in three ways: • by software command (see GE863-QUAD Software User Guide) • by hardware shutdown When the device is shut down by software command or by hardware shutdown, it issues to the network a detach request that informs the network that the device will not be reachable any more. 2.2.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 NOTE: don't use any pull up resistor on the RESET# line nor any totem pole digital output. Using pull up resistor may bring to latch up problems on the GE863-QUAD power regulator and improper functioning of the module. The line RESET# must be connected only in open collector configuration.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 3 Power Supply The power supply circuitry and board layout are a very important part in the full product design and they strongly reflect on the product overall performances, hence read carefully the requirements and the guidelines that will follow for a proper design. 3.1 Power Supply Requirements The GE863-QUAD power requirements are: • Nominal Supply Voltage: 3.8 V • Max Supply Voltage: 4.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 3.2.1 Electrical design Guidelines The electrical design of the power supply depends strongly from the power source where this power is drained. We will distinguish them into three categories: • +5V input (typically PC internal regulator output) • +12V input (typically automotive) • Battery 3.2.1.1 + 5V input Source Power Supply Design Guidelines • The desired output for the power supply is 3.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 3.2.1.2 + 12V input Source Power Supply Design Guidelines • The desired output for the power supply is 3.8V, hence due to the big difference between the input source and the desired output, a linear regulator is not suited and shall not be used. A switching power supply will be preferable because of its better efficiency especially with the 2A peak current load represented by the GE863-QUAD.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 3.2.1.3 Battery Source Power Supply Design Guidelines • The desired nominal output for the power supply is 3.8V and the maximum voltage allowed is 4.2V, hence a single 3.7V Li-Ion cell battery type is suited for supplying the power to the Telit GE863-QUAD module. The three cells Ni/Cd or Ni/MH 3,6 V Nom.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 important. It must be ensured that the maximum battery voltage is never exceeded, otherwise the battery may be damaged and even explode. Moreover for the constant voltage final chargers, the constant voltage phase (final charge) must not start before the battery voltage has reached its maximum value, otherwise the battery capacity will be highly reduced.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 NOTE: For all the threshold voltages, inside the GE863-QUAD all threshold are fixed in order to maximize Li-Ion battery performances and do not need to be changed. NOTE: In this application the battery charger input current must be limited to less than 400mA. This can be done by using a current limited wall adapter as the power source. 3.2.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 This generated heat will be mostly conducted to the ground plane under the GE863-QUAD, you must ensure that your application can dissipate it. 3.2.3 Power Supply PCB layout Guidelines As seen on the electrical design guidelines the power supply shall have a low ESR capacitor on the output to cut the current peaks and a protection diode on the input to protect the supply from spikes and polarity inversion.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 4 Antenna The antenna connection and board layout design are the most important part in the full product design and they strongly reflect on the product overall performances, hence read carefully and follow the requirements and the guidelines for a proper design. 4.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 • If you don't have EM noisy devices around the PCB of GE863-QUAD, by using a strip-line on the superficial copper layer for the antenna line, the line attenuation will be lower than a buried one; 4.3 Antenna installation Guidelines • Install the antenna in a place covered by the GSM signal.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 5 Serial Port The serial port on the Telit GE863-QUAD is the core of the interface between the module and OEM hardware. Several configurations can be designed for the serial port on the OEM hardware, but the most common are: - RS232 PC com port - microcontroller UART @ 2.8V - 3V (Universal Asynchronous Receive Transmit) - microcontroller UART@ 5V or other voltages different from 2.
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Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 5.1 RS232 level translation In order to interface the Telit GE863-QUAD with a PC com port or a RS232 (EIA/TIA-232) application a level translator is required.
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Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 5.2 5V UART level translation If the OEM application uses a microcontroller with a serial port (UART) that works at a voltage different from 2.8 - 3V, then a circuitry has to be provided to adapt the different levels of the two set of signals. As for the RS232 translation there are a multitude of single chip translators, but since the translation requires very few components, then also a discrete design can be suited.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 NOTE: The UART input line TXD (rx_uart) of the GE863-QUAD is NOT internally pulled up with a resistor, so there may be the need to place an external 47KΩ pull-up resistor, either the DTR (dtr_uart) and RTS (rts_uart) input lines are not pulled up internally, so an external pull-up resistor of 47KΩ may be required. A power source of the internal interface voltage corresponding to the 2.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 6 Microphone The microphone circuitry is the more noise sensitive and its design and layout must be done with particular care. 6.1 Microphone line Characteristic and requirements The Telit GE863-QUAD provides two audio paths for the microphone and the earpiece: the internal and the external audio paths. Only one of the two paths can be active at a time and it is selectable by hardware line AXE or by AT command.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 TIP: Due to the difference in the echo canceller type, the internal audio path is suited for handset applications while the external audio path is suited for car kit hands free. The headset applications should be made by using the external audio path but DISABLING the echo canceller by software AT command.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 10dB lower with respect to the calculated value for a nominal sensitivity. The corresponding reduction in signal level will be compensated by an increased voice volume of the talker which will speak louder because of the ambient noise. For the headset we shall distinguish two different types: the headsets having the microphone sustained close to the mouth and the headsets having the microphone on the earpiece cable.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 6.2 General Design Rules There are several configurations for the audio path, but the most effective difference is between balanced and unbalanced microphone. It is highly recommended to keep the whole microphone path balanced even if this means having 2 wires connecting the microphone instead of one needed (plus ground) in the unbalanced case.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 6.3.1Balanced Microphone biasing The balanced microphone bias voltage should be obtained from a dedicated voltage regulator, in order to eliminate the noise present on the power lines. This regulator can be the same for all the audio paths. The microphone should be supplied from a capacitor multiply circuit.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 6.3.2 Unbalanced Microphone biasing The unbalanced microphone biasing voltage should be obtained from a dedicated voltage regulator, in order to eliminate the noise present on the power lines. This regulator can be the same for all the audio paths. The microphone should be supplied from a capacitor multiply circuit.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 6.4 Microphone buffering As seen previously, a microphone shall be connected to the input pads of the GE863-QUAD through a buffer amplifier that boosts the signal level to the required value. Again the buffered microphone circuitry can be balanced or unbalanced. Where possible it is always preferable a balanced mic. solution.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 The C636 and C637 capacitors are placed in order to cut off the gain at higher frequencies than the transmitted GSM band, the cutoff frequency (-3dB) should be 8 kHz in order to have -1dB at 4kHz. The cutoff frequency is given by the formula: freq.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 6.4.2 Buffered Unbalanced (Single Ended) Mic. A sample schematic for a buffered unbalanced (single ended) microphone can be: The schematic does not include the required mic. biasing circuitry. For the biasing the same circuit as seen before can be used; to be noticed that the capacitor C3 on the unbalanced biasing circuit is not anymore needed if this Buffered design is used.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 As shown in the balanced buffered mic. the gain adjustments can be done by changing R719 R720 and R708 - R711 and as a consequence the capacitors C726 and C727. The bandwidth (-3dB) is given by the approximated formula (considering C725 >> C726) : 1 1 = [Hz] 2π * R719 * C 726 2π * R711* C 727 The buffer bandwidth at -3dB shall be 8kHz.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 R711 = gain* R708= 1.5* 10 = 15 kΩ R719 = (gain -1) * R720 = (1.5 -1) * 10 = 5 kΩ The commercial values of 15kΩ & 5.6kΩ are then chosen. As a consequence the values of the capacitors C726 and C727 shall be: C726= 1/ (2π*8000*R719)= 3.5 *10 -9 F C727= 1/ (2π*8000*R711)= 1,2 *10 -9 F The commercial values of 3.3nF and 1nF are then chosen.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 7 Speaker 7.1 Speaker lines characteristics and requirements The Telit GE863-QUAD provides two audio paths for both the microphone and the earpiece: the internal and the external audio paths. Only one of the two paths can be active at a time and it is selectable by hardware line AXE or by AT command.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 external speaker path ( EAR_HF+ , EAR_HF- ) • line coupling: DC • line type: bridged • speaker impedance (operating conditions): ≥ 16 Ω ± 15% @ 1kHz • minimum load impedance: 15 Ω • signal bandwidth: 150 - 8000 Hz @ -3 dB • maximum differential output: 425 mVrms • rated output power: 2.5 mW • maximum power output: 7.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 high power external ear • line coupling: DC • line type: bridged not referred to GND • speaker impedance (operating conditions): ≥4Ω • minimum load impedance: 4Ω • signal bandwidth: 150 - 8000 Hz @ -3 dB • maximum power output: 6W • THD+N 10% @ 6 W 7.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 7.2.1 Noise Filtering The I/O of the PCB should have a noise filter close to the connector, to filter the high frequency GSM noise. The filter can be a Π of 2 capacitor and a inductance, with the one capacitor of 39pF - 0603 case , and the other capacitor of 1nF - 0603; the inductance shall have a value of 39μH . 7.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 The resulting gain and high pass cut can be obtained with the formula: Gain = R3 R2 1 [Hz] 2π * R3 * C 4 And an example of internal Ear amplifier is: freq.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 Some amplifier require a low impedance load at high frequency in order to avoid auto oscillation, this can be made with a capacitor (100nF) in series with a resistor (15Ω). When designing your application, remember to provide an adequate bypass capacitor to the amplifier and place it close to the power input pin of the IC, keeping the traces as short as possible. 7.
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Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 8.3 Using the Alarm Output GPIO6 The GPIO6 pad, when configured as Alarm Output, is controlled by the GE863-QUAD module and will rise when the alarm starts and fall after the issue of a dedicated AT command.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 9 Camera 9.1 Agilent Camera The GE863-QUAD provides a direct support for digital cameras with the following characteristics: Type: AGILENT ADCM2650 Technology: CMOS COLOR camera Max picture size: VGA 640x480 pixels Output format: JPEG Sensitivity: 5 lux 9.1.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 32 IICSDA GPIO4 I/O IICbus serial data 3 S_DATA I/O 53 CAM_DRDY GPIO5 I Data ready in an output for the camera and an input for the GE863-QUAD 7 DR O 31 VOUT O power supply for the camera 2 VCC_MAIN I - - - Horizontal sync n.c. 6 HSYNC O 51 OE_CAM GPIO7 O Input command for switching power ON or OFF 5 ON_OFF I 56..
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 9.2 Transchip Camera The GE863-QUAD provides a direct support for Transchip digital cameras with the following characteristics: Type: TRANSCHIP TC5747 Technology: CMOS COLOR camera Max picture size: VGA 480x640 pixels landscape Output format: JPEG Sensitivity: 4 Lux 9.2.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 31 VAUX 32 GPIO4 8-17.. GND 6 GPIO8 8-17… GND O Power Supply 19 DVDD28 I I/O I2C bus serial data 20 SDIN I/O Ground 21 PS1 I Camera power type selector 22 PS2 I Ground 23 SHIELD - Flash Enable 24 LED_CTRL O O * Filter the AVDD28. Use a Buffer between module clk out, MON1_CAM and camera clk in, CLK_IN. *** Non-connected. ** Fig 1.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 Fig 2.
Telit GE863-QUAD / GE863-PY Hardware User guide 1vv0300697, Rev. ISSUE#0, - 21/11/05 9.2.2EVB for Agilent and Transchip camera support In order to interface the Telit GE863-QUAD with a CMOS camera, Telit has developed an evaluation board. The EVK allows the connecton of all Telit modules through 2 connectors of 40 pins each. The I2CBUS DUAL CAMERA board is plugged in the 2 connectors of 30 pins each on the module board.
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