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Author Topic: Can't locate TX and RX on my GSM board  (Read 1936 times)
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I recently bought this TC35 GSM board:
http://www.ebay.com/itm/261006967389?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

I located VCCIN and GND pins, but I can't find TX and RX.

There are pins labeled: EPN1, EPP1, EPN2, EPP2, MICN1, MICP1, MICN2, MICP2 which I believe are for microphone and earphone.
There are also 10 pins A B C D E (each letter has 2 pins).
Another group of holes are labeled A0, A1, A2, A3, D0, D1, D2, D3, D4, D5, D6, and DCSH.

I want to connect this board to my Arduino UNO, so I need to find TX and RX on this board.
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I'd go with D0 and D1.
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I got some photos and schematic for this TC35 GSM board, but I am still not sure which pins to connect to Arduino UNO.

On this photo: https://app.box.com/s/qldx0q0y47kr8sgwwqlj you can see the following pins: RXD0, TXD0, RXD_MCU, TXD_MCU, RXD_PC, TXD_PC, RXD, TXD, RI, TI. I don't know which pair to use to connect to Arduino's pins 2 and 3.

I read somewhere that I should also connect the ground of GSM shield to the Arduino's GND. The only pin on GSM shield which has a label GND is the one on the top of this photo: to the right of white ON/OFF switch - there you can see two pins - one is VCC and the other is GND. Should I connect this GND to Arduino's GND? On Arduino board there is one GND next to Vin, another next to 5V, and the third one is next to PIN 13.

I also read that I should connect Arduino PIN 7 to GSM shield Reset, but I don't find Reset pin on the GSM shield.

Is it OK if I power the GSM shield with 9V battery?

Here is schematic for this board: https://app.box.com/s/ej4kux0y0i2nqbek4796

And here is another photo: https://app.box.com/s/wdvnazamhzwfuagg0y4x

I read many instructions, but no GSM shiled is the same as mine, I tried hundreds combinations, with softwareSerial library and without it, just trying to communicate with the modem, but no success.

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Upper right hand corner, looks like a jumper block?
RXD MCU, TXD MCU
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There is one jumper on the board, but it is on the bottom left on the photo, not top right. Still I don't know how and why to use this jumper. I am new to Arduino and electronics, so I need simple and straight instructions.
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Upper right hand of schematic, where are those 10 pins?
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Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
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I see. I don't understand schematic, I put a link here for someone who understands it and can hopefully help me. My board looks the same as the one on the pic, except for pins A0..A3, D0..D6, DSCH, which have male pins on the photo, but on my board there are just holes.
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