Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 T el i t G M 8 6 2 -Q U A D GM862-QUAD-PY Hardware User Guide Telit Communications S.p.A.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 Contents 1 OVERVIEW 4 2 HARDWARE COMMANDS 5 2.1 Turning ON the GM862-QUAD 5 2.2 Turning OFF the GM862-QUAD 2.2.1.1 Hardware shutdown 2.2.1.2 Hardware Unconditional Reset 7 7 7 3 POWER SUPPLY 9 3.1 Power Supply Requirements 9 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 GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 6 6.1 SPEAKER Speaker lines characteristics and requirements 34 34 6.2 General Design rules 6.2.1 Noise Filtering 36 36 6.3 Handset earphone design 36 6.4 Hands Free earphone (low power) design 38 6.5 Car Kit speakerphone design 38 7 GENERAL PURPOSE I/O 40 7.1 Using a GPIO pin as INPUT 40 7.2 Using a GPIO pin as OUTPUT 40 7.3 Using the Alarm Output GPIO6 41 7.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 1 Overview The aim of this document is the description of some hardware solutions useful for developing a product with the Telit GM862-QUAD/-QUAD-PY modules. 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 GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 2 Hardware Commands 2.1 Turning ON the GM862-QUAD To turn on the GM862-QUAD the pin ON# must be tied low for at least 1 second and then released. The maximum current that can be drained from the ON# pin 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.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 2.2 Turning OFF the GM862-QUAD The turning off of the device can be done in three ways: • by software command (see GM862-QUAD Software User Guide) • by hardware shutdown • by hardware unconditional 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.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 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 GM862-QUAD power regulator and improper functioning of the module. The line RESET# must be connected only in open collector configuration.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 3 Power Supply The power supply circuitry and board layout are the most 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 GM862-QUAD power requirements are: • Nominal Supply Voltage: 3.8 V • Max Supply Voltage: 4.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 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 GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 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 GM862-QUAD.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 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 GM862-QUAD module. The three cells Ni/Cd or Ni/MH 3,6 V Nom.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 Once the battery voltage reaches its maximum voltage then the process goes into its third state: Final charging. The voltage measure to change the process status into final charge is very important. It must be ensured that the maximum battery voltage is never exceeded, otherwise the battery may be damaged and even explode.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 An example of battery charger can be: NOTE: In this particular application the battery charger input current must be limited to less than 1A. This can be done by using a current limited wall adapter as the power source. For your convenience in the EVK there's also a current unlimited input, where the input source is not limited in current and the drawn current is limited to about 0,5A by a MOSFET in the EVK. 3.2.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 If we assume that the device stays into transmission for short periods of time (let's say few minutes) and then remains for a quite long time in idle (let's say one hour), then the power supply has always the time to cool down between the calls and the heat sink could be smaller than the calculated one for 350mA maximum RMS current, or even could be the simple chip package (no heat sink).
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 • The placement of the power supply on the board should be done in such a way to guarantee that the high current return paths in the ground plane are not overlapped to any noise sensitive circuitry as the microphone amplifier/buffer or earphone amplifier. • The power supply input cables should be kept separate from noise sensitive lines such as microphone/earphone cables.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 4 Serial Port The serial port on the Telit GM862-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 GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 4.1 RS232 level translation In order to interface the Telit GM862-QUAD with a PC com port or a RS232 (EIA/TIA-232) application a level translator is required.
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Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 4.2 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 GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 NOTE: The UART input line TXD (rx_uart) of the GM862-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 GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 5 Microphone The microphone circuitry is the more noise sensitive and its design and layout must be done with particular care. 5.1 Microphone line Characteristic and requirements The Telit GM862-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 GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 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 GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 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 GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 5.2 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 GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 5.3.1 Balanced 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 GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 5.3.2 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 GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 5.4 Microphone buffering As seen previously, a microphone shall be connected to the input pins of the GM862-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 GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 freq. = 1 1 = [Hz] 2π * R 604 * C 637 2π * R606 * C 636 For example: - Let's assume you have a microphone with these characteristics: - sensitivity -45 dBVrms/Pa and you want to use it in the internal mic. audio path. With the mic. having nominal sensitivity -45dBVrms/Pa at the "normal spoken" conditions: -4.7dB Pa at 7 cm from the mouth of the talker.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 5.4.2 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 GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 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. Note that the biasing of the operational amplifier is given for the inverting amplifier by the series divider R714-R715. The 100nF capacitor C719 is needed to filter the noise that could be coupled to that divider.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 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 GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 6 Speaker 6.1 Speaker lines characteristics and requirements The Telit GM862-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 GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 • maximum power output: 7.5 mW • volume level steps (SW): - 2 dB • number of volume steps (SW): 10 The EVK v.1.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 6.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 (if speaker impedance is bigger than 16Ω) or the GM862-QUAD ear port may be damaged (if speaker impedance is less than 15Ω). The other limitation of the speaker direct connection is the power output capability of the GM862QUAD which is limited and for some particular applications may not be enough.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 And an example of internal Ear amplifier is: 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. 6.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 • The amplifier shall have a mute control to be used while not in conversation. This results in two benefits: eliminating the background noise when not in conversation and saving power. • The power to the amplifier should be decoupled as much as possible from the GM862-QUAD power supply, by either keeping separate wires and placing bypass capacitors of adequate value close to the amplifier power input pins.
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Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 7.3 Using the Alarm Output GPIO6 The GPIO6 pin, when configured as Alarm Output, is controlled by the GM862-QUAD module and will rise when the alarm starts and fall after the issue of a dedicated AT command.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 8 Camera 8.1 Agilent Camera The GM862-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 8.1.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 48 CAM_DRDY 50 CAM_PWR_ON O 2-4- GND 6 I Data ready in an output for the camera and an input for the GM862-QUAD 7 DR 2,8V power supply enable for the camera 2 VCC_MAIN I Horizontal sync n.c.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 NOTE: GM862-QUAD is 100% pin-to-pin compatible with previous GM862 models. Therefore, in order to connect the camera to the standard 50-pins Molex industrial connector, some pins will have dualfunction (GPIO pins, except for GPIO1): as usual GPIO operations or CAMERA support. See Molex PINOUT described in the GM862-QUAD Product description. NOTE: The CMOS camera must be removed when the GPIO pins are used for I/O purpose.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 8.2 Camera Transchip The GM862-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 8.2.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 50 n.c 16 VCLKOUT O n.c 17 VALIDH O n.c 18 VALIDV O 19 DVDD28 I 20 SDIN I/O Ground 21 PS1 I Camera power type selector 22 PS2 I Ground 23 SHIELD - Flash Enable 24 LED_CTRL O GPIO7 O CAM_PWR_ON 47 GPIO4 External 2.8V Regulator enable controlled by CAM_PWR_ON pin I/O I2C bus serial data IICSDA_CAM 2-4-6 GND 32 GPIO8 O PD(0) 2-4-6 GND * Filter the AVDD28.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 8.2.2EVB for Agilent and Transchip camera support In order to interface the Telit GM862 with a CMOS camera, Telit has developed an evaluation board. The EVK allow connecting 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.
Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 8.2.
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Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev. ISSUE#0, - 04/10/2005 8.2.
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Telit GM862-QUAD/-QUAD-PY Hardware User Guide 1vv0300692, Rev.
SO104 GND 10% 7 81 D S G 1 9 0 11 ! WARNING!!!! Max current limit must be properly set for the size of battery in use Keep max current around 1/2 of battery pack capacity E.g. 1000mAh -> 500 mA max Curr. limit is given by R102 to R105 2 3 . DPAK-2S 2SJ387S Q102 CR32 10% 4.7nF X7R 50V 0603 FCMM0502 4.7 C101 1 CR32 2 10% 6 Vcc 4.7 + - CR32 BATTERY CHARGER INPUT 6 10% CURRENT UNLIMITED 4.7 5 4.
13 2 4 5 6 7 81 9 0 11 A ALL RIGHTS RESERVED REPRODUCTION AND DISCLOSURE FORBIDDEN +5V input linear regulator U201 SO201 LT1528CQ FCMM0502 +5V INPUT 4,5V-8 Vcc + - 1 5 2 4 DZ201 D205 6KA24 STPS140Z .
13 2 4 5 6 7 81 9 0 11 A +3.
13 2 4 5 6 7 81 9 0 11 L401 0.35 +3.7V 4312-020 noMount=YES L403 220 C405 C404 100nF X7R 16V 0603 100pF COG 50V 0603 L404 220 BLM21 SO402 ALL RIGHTS RESERVED REPRODUCTION AND DISCLOSURE FORBIDDEN GPI01 STAT_LED RX_PROG CTS RING DSR DCD TX_PROG DTR RTS GND PWR_GND +3.7V 100pF COG 50V 0603 C401 PL401 33pF COG 50V 0603 GND_EXT 53748-0504 1 2 3 4 4312-020 GND MIC_MT+ MIC_HF+ MIC_MTON START RESET GPI02 AXE C402 100nF X7R 16V 0603 0.
13 2 4 5 6 7 81 9 0 11 +3.7V +3.7V R503 560 R510 5% 1215061-02F TP501 22K PL506 0603 5% 0603 1 PLCC2 YELLOW GREEN - GPIO2 LED GPIO2 OUTPUT A ON 004:4D GPIO2 004:5D 2 LY-T670HK DL503 ON BUTTON +3.7V 3 3 TC7S08FU C501 1 Q503 U501 4 2 47K SOT-323 WEs 2 47K 4 5 VCC_1 GND_1 3 1 SKHHAL Q506 2 BCR148W 47K 2 U501 SOT-323 WEs TC7S08FU 1 +3.
13 2 4 5 6 7 81 9 0 11 BALANCED MICROPHONE POLARIZATION +3V_INT_MIC_BAL R601 10K 5% 0603 3 Q601 BALANCED MICROPHONE BUFFER +24 dB DECOUPLING CAPACITORS 2 A C601 SO605 1 IO INT_MICGND GND 5% 0603 100nF Y5V 16V 0603 C608 10K 100nF Y5V 16V 0603 U602 TS3V912ID 7 V+OUT V- 6 BALANCED 3 SINGLE ENDED INT MIC POWER SELECTION - GND GND C636 GND + 2 4 J01001A1944 GND 1 100nF Y5V 16V 0603 1nF X7R 50V 0603 8 5 1215061-03F 54 32 GND B 5% 0603 C615 1nF X7R 50V 0603 PL60
13 2 4 5 6 7 81 9 0 11 BALANCED MICROPHONE POLARIZATION +3V_EXT_MIC_BAL R705 10K 5% 0603 3 Q702 A 2 BC847BW DECOUPLING CAPACITORS SOT-323 1Fs BALANCED MICROPHONE BUFFER +10 dB C702 1 4.
13 2 4 5 6 7 81 9 0 11 10pF COG 50V 0603 A 5% 0603 56K R802 C803 INTERNAL EAR AMPLIFIER +6dB NOISE FILTERING SO801 C804 J01001A1944 39pF COG 50V 0603 1 IO 54 32 220uF INT_EAR- C820 SO806 C805 39nH LQG18 39pF COG 50V 0603 C806 C807 1nF X7R 50V 0603 1nF X7R 50V 0603 C821 C822 100nF Y5V 16V 0603 100nF Y5V 16V 0603 R807 7 GND 3 100nF Y5V 16V 0603 5% 0603 0603 EAR_MT004:3D;006:10D C801 1uF X5R 6.
13 2 4 5 6 7 81 9 0 11 HIGH POWER EXT EAR AMPLIFIER (6W) +12V R901 U901 5% 0603 100nF Y5V 16V 0603 5% 0603 10K OUT+ 15K 5% IN+ 3 220 R902 1.
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Telit GM862-QUAD Hardware User guide 1vv0300692, Rev.
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