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[on:]

Buongiorno,

la mia domanda è semplice, ma non banalissima credo:
è possibile collegare arduino uno direttamente al modulo sim tipo quello indicato qui ?
http://www.futurashop.it/allegato/7100-FT971.asp?L2=MODULI%20GSM&L1=MODULI%20GSM%20E%20SISTEMI%20GPS&L3=&cd=7100-FT971&nVt=&d=65,00
assolutamente senza passare attraverso moduli shield che mi implementino audio o altre funzioni che non mi necessitano ?

In teoria credo che sarebbe sufficiente collegare Rx/Tx arduino - Sim900, eventualmente condividendo (integrando) alimentazione e ground

In effetti potrei solo inviare e ricevere messaggi sms, ma nel mio caso per un controllo robotico sarebbe perfetto.
Cosa ne pernsate ?

Grazie

[Reply #1 on:]

For extension i traslate my question:

hi boy,

do you think is possible connect sim900 Rx Tx directly to arduino uno pin ?

I know that in this case i can activate only sending and receiving message, but it is ok for me because i want only a minimal remote control

do you think is possible or shield is necessary ?

Thanks a lot for your suggestions.

[Reply #2 on:]

do you think is possible connect sim900 Rx Tx directly to arduino uno pin ?

I presume you mean pins (plural). If so, yes, you can. Don't forget ground, too. And probably power, although the chip might take more power than the Arduino can provide.

[Reply #3 on:]

Soldering could be hard especially for the sim card holder and the chip. What voltage is the chip requiring? You can use an ac adapter to power arduino and power the chip's separate voltage regulator with arduino vin pin, which is connected to ac adapter.

[Reply #4 on:]

Thank you for your reply,

yes, i mean pins, one for Rx and one for Tx

may be it is not necessary soldering, because it's possible to use jumpers, breadboard, usb cable and not more others for experimental assembly

for connect Sim900 as this "http://www.futurashop.it/allegato/7100-FT971.asp?L2=MODULI%20GSM&L1=MODULI%20GSM%20E%20SISTEMI%20GPS&L3=&cd=7100-FT971&nVt=&d=65,00" with arduino i think 2 ways:
1 - female - female jumpers
2 - male - female jumpers, mounting components on breadboard

Your right, i need to remember power and ground

What do you think ? For library i need only of sim900.h, SoftwareSerial.h and inetGsm.h ?

For appropriate power i think to cellular slim battery 1000mAh when usb cable is disconnected .
 

[Reply #5 on:]

I can't read that page but it seems to say 3.2V to 4.8V so is that range of voltage for the GPRS? Then you can't connect the RX TX directly but need level shifter.

[Reply #6 on:]

Choose power supply carefully - usually GSM module can take up to 2 Amps! in peak; even then voltage shouldn't drop below 3.3V. I can see your GSM card has very simple interface (I like it - mine has 30 pins), but can you send AT commands just after powering it up? I've looked into 2 different GSM modules and both require quite unique start-up procedure.

Anyway, which library are you going to use to control GSM module?

[Reply #7 on:]

I can't read that page but it seems to say 3.2V to 4.8V so is that range of voltage for the GPRS? Then you can't connect the RX TX directly but need level shifter.

Can you explain it? Why there's a need for a level shifter?

[Reply #8 on:]

The SIM900 GSM module need of 3,2 ~ 4,8 V
i think is similar to 4,8V of arduino.
a current swifter for V regulation ? Is very good solution !  

Better than 2 battery

I test the configuration and i post the results

thanks

[Reply #9 on:]

Anyway, which library are you going to use to control GSM module?

I do not know which library is better to use, I'll try first with this two standard library:
sim900.h
SoftwareSerial.h

then i will try to send at commands

on the web there are a lot of shield, more or less complex, but with few similar problem

I hope to find the minimal configuration and more compact as possible

[Reply #10 on:]

I can't read that page but it seems to say 3.2V to 4.8V so is that range of voltage for the GPRS? Then you can't connect the RX TX directly but need level shifter.

Can you explain it? Why there's a need for a level shifter?

Because I can't read that language, only a few numbers. If that range is the power supply range, I am inclined to power the module with 3.3V and then the logic will probably be 3.3V so arduino 5V logic will need conversion.

[Reply #11 on:]

Hi,
you can find the shield schematic here http://www.open-electronics.org/gsm-gps-shield-for-arduino/
So you can chose whato use anc what remove from your application.
The shield is not very expensive...
http://store.open-electronics.org/GSM_GPRS_GPS_SHIELD

GSM/GPRS & GPS shield for Arduino
Price: 16.20€
5 or more 15.39€
10 or more 14.58€
50 or more 12.96€
100 or more 12.15€

The module with SIM908 (cod. FT971)
http://store.open-electronics.org/Breakout/GSM%20Breakout/Small_Breakout_SIM908
Price: 53.72€
5 or more 51.03€
10 or more 48.35€
50 or more 42.98€
100 or more 40.29€