M10 User Manual
M10 User Manual Contents Contents ........................................................................................................................... 1 0. Revision history ............................................................................................................. 4 1. Introduction ................................................................................................................... 5 1.1. Reference .....................................................................
M10 User Manual Table Index TABLE 2: DIGITAL I/ O ELECTRICAL CHARA CTERISTICS..................................................................
M10 User Manual Figure Index FIGURE 1: PIN ASSIGNM ENT ........................................................................................................................... 9 FIGURE 2: RECOMM ENDATION OF PLA CEM ENT ................................................................................. 15 FIGURE 3: PLACEMENT CLEARANCE ................................................................................................... 16 FIGURE 4: CIRCUIT OF THE SIM CARD .....................................
M10 User Manual 0. Revision history Revision 1.
1. Introduction This document gives recommendation for M10 module integration in a wireless application, such as vehicle tracking system, smart metering and PDA. It gives some recommendations for design notes, reference circuit and PCB layout. The M10 is a Quad-band GSM/GPRS engine that works at frequencies of GSM850, and PCS1900. M10 features GPRS and supports the GPRS coding schemes CS-1, CS-2, CS-3 and CS-4. With a tiny profile of 29mm ×29mm ×3.
2. Product Concept The M10 is a Quad-band GSM/GPRS engine that works at frequency bands of GSM850 and PCS 1900. The M10 features GPRS multi-slot class 12 and supports the GPRS coding schemes CS-1, CS-2, CS-3 and CS-4. The M10 is an SMD type module with 64-pin pads and a tiny profile of 29mm x 29mm x 3.6 mm (the thickness of PCB is 1.6mm), which can fit into almost all customers’ applications. It provides all hardware interfaces between the module and customer’ host board.
Mechanical dimensions of module
3. Placement Please pay attention to the placement and the PCB layout in your application design. 3.1. Pin Assignment The pin assignment of the M10 module is shown in Figure 1. Placement of module should be carefully considered to make the RF_IN pad as close as possible to antenna so as to reduce overall RF trace length. The longer the RF trace to antenna, the larger the RF insertion loss.
Figure 1 : Pin assignment
3.2. Placement recommendation The analog part components such as microphone should be placed far away from antenna and power supply. General placement recommendation is shown in Figure 2. Power Supply Digital Part & Other Part UART Interface Power LCD Interface Antenna RF Module SIM Interface Keypad Interface Pwrkey&Audio Interface Audio Part Keypad Part Figure 2 : Recommendation of placement 3.3. Placement clearance The module mounts with 64 SMT pads.
Figure 3: Placement clearance
4. Digital I/O Connection If the voltage level of peripheral interface circuit does not match module interface, the power consumption of the system could increase, and could even cause the module damaged. Each digital I/O of the module operates in a 2.8V logic level inside the module. The voltage level of those digital interfaces connected to the module should match the electrical characteristics of the module listed in Table 2.
5. VDD_EXT Pin This pin is a power supply from a regulator inside the module which can supply current of about 20mA. Customer can also use this pin to judge whether the module is off or not. When the module is turned off, the VDD_EXT pin will change from high level to low level.
6. Serial Interface and Debug Interface The TXD and RXD pins should be connected to host MCU. The DTR pin should be controlled to trigger SLEEP mode or wakeup the module. The RTS and CTS pins should be connected to the host MCU if hardware flow control is required. The TXD, RXD, PWRKEY and GND pins can also be used for software upgrade and high-level acoustic parameters configuration. The DBG_TXD and DBG_RXD pins are only used for software debug.
7. SIM Card As shown in Figure 4, connecting a large volume capacitor such as 10uF in the SIM_VDD line could lead to failure of detecting the SIM card. A capacitor between 100nF and 1uF is recommended.
8. SLEEP Mode The command AT+CSCLK can enable or disable SLEEP mode. When the SLEEP mode is enabled, pulling the DTR pin to high level would drive the module into SLEEP mode; and pulling the DTR pin to low level the module would exit from SLEEP mode.
9. Audio Trace If possible, the audio trace should be placed in inner layer, and shielded by ground in the same layer and the upper and lower adjacent layers to prevent from RF interference. In addition, it is recommended to add as many via as possible between ground layers so as to reduce RF noise. The AGND signal is usually used for AOUT2 channel to establish a single-end output with SPK2P.
10. RF Design Guide Correct RF design is essential for RF performance such as transmitting power, receiving sensitivity and harmonics. Following this RF design guide could benefit to improve the RF performance of customer’s product. 10.1. Recommended Impedance Matching Circuit The impedance of M10’s RF_ANT port is 50Ω. If the impedance of antenna is close to 50Ω in all working frequency bands, the antenna could be connected to the RF_ANT port directly via 50Ω transmission line.
NOTE: The impedance of traces in Bold type must be 50Ω. 10.2. Matched RF Transmission Line Design In PCB layout, a matched RF transmission line has a fixed characteristic impedance, which is called Z0, from its source to its load. The source should have an internal resistance of Z0 and the resistance of matching load should close to Z0. Since the impedance of M10’s RF_ANT port is 50Ω, the impedance of the RF transmission line from this port to the antenna or the matching circuit should also be made to 50Ω.
Control the impedance of RF trace as close as possible to 50Ω. If the thickness between RF_ANT pad and the ground layer is less than 0.4mm, it could significantly decrease the output power. Therefore, when they are too close, we strongly suggest removing the copper in the layer beneath the RF_ANT pad. If RF trace routes to another layer, add GND via along with it to keep GND integral. The clearance between RF trace and ground plane in same layer should be at least twice the RF trace width.
RF PAD Matching L2 under ANT PAD GND PAD ANT PAD L2 under RF PAD Under RF TEST point Layer1 Layer2 L3 under ANT PAD L4 under ANT PAD Layer3 Layer4 Figure 9: Reference PCB design w ith antenna pad in a four-layer PCB If RF connector is adopted, place the RF connector close to module RF_ANT, and add several ground via close to the GND PAD of RF connector. Figure 10 is the reference PCB design.
Matching Under RF connector RF connector Under RF PAD RF PAD Under RF TEST point Layer1 Layer3 Layer2 Layer4 Figure 10: Reference PCB design w ith RF connector in a four-layer PCB The stack-up of the four-layer PCB is shown in Figure 11.
11.
FCC Statement Any Changes or modifications not expressly approved by the party responsible for compliance could void the user’s authority to operate the equipment. FCC RF exposure statement: This equipment complies with FCC radiation exposure limits set forth for an uncontrolled environment. This equipment should be installed and operated with minimum distance 20cm between the radiator& your body.This transmitter must not be co-located or operating in conjunction with any other antenna or transmitter.