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AVL with G20 Motorola GSM Module

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gorkin

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price g20 motorola

Hi my brothers!
Anyone have experience with G20 GSM module for AVL application? I build one project with G20, Leadtek GPS module and PIC18LF6722, for power supply I use LM2576 ADJ step-down switching regulator...If anyone interested I can post the schematic here for give Your critics.

Thanks a lot, Gorkin.
 

linoko

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g20 motorola nasıl

Hi Gorkin,
I'm very intereted about you project, please post you schematic and hex or source file i want to build one device to myself.
Best Regards Linoko

Sorry about my English
 

Nightmare

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motorola g20 source

Hi Gorkin,

It would be great if you could post the schematic as well as the code.

Thanks in Advance
 

Justins

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g20 gsm module

If anyone is looking for GPS device with best quality and price - pm me
 

gorkin

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avl module

Hi brothers!
Forgive-me for long time between my questions above and the schematics post...But it´s necessary for exaustive evaluation and debbuging. Above, anyone can upload the latest schematic...

Now, I have some doubts:
(1). When I connect one satelital modem in serial USART, the microcontroller not receive any valid data from the external satelital modem, all data are corupted (its happens only with satelital modem, if I connect one PC Serial Port in serial USART board, serial communication function perfectly). Whats are wrong?

(2). U404 (Low DropOut voltage regulator) not delivery +2.80V in output, but more than +3.2V... I am suspect of distance between decoupling electrolyte capacitors and the IC, anyone have the same problem one time?

(3). When I using UART interface for communicating with G20 module and switch for communicating with USB interface (using one PC or PDA for example), the "host" USB not detect the USB "peripheral" (In my case, the G20 module). Reading the hardware manual interface of G20 module I founded that I must put all serial UART microcontroller pins in high impedance mode. In the schematic, this is acquire by disabling the SN74LVC244 buffer (after microcontroller detect by USBDT pin the presence of USB "host")...But I am not have any sucess. When I remove the SN74LVC244 buffer, the USB "host" detect the USB "peripheral" (in my case, the G20 module). Anyone have any information about the internal construction of the SN74LVC244 buffer? It´s possible the internal construction of the gates offers low impedance for G20 serial circuits?

(4). The audio stage function, but maybe function well, anyone have other idea for this stage?


PS: My PCB board was realized with 4 layers...it´s really necessary? Because 4 layers is very expensive...

Thanks in advance, Gorkin.
 

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