I get this compiling error with your lib? Do I need additional libs?
In file included from GPRSTest.ino:8:
C:\Program Files\Arduino\libraries\SIM800/SIM800.h: In member function 'bool CGPRS_SIM800::available()':
C:\Program Files\Arduino\libraries\SIM800/SIM800.h:79: error: 'Serial1' was not declared in this scope
Are you powering SIM800 with 4V? I had something like that because i forgot to add a diode to lower the voltage from 5V.
Also check your APN name, those messages showed are when code is trying to set APN.
And if using an external power source, don't forget to connect a common GROUND between power source and arduino
CatweazleNZ:
I have one of these running on a Freetronics Ethermega. I am only using it to send and receive sms text messages.
The reset pin on these run at 2.8 volts output - you do not supply 2.8 volts to the reset pin. You ground the reset pin momentarily to do a hard reset on these devices.
I confirm you need a separate about 4 volt, 2 amp power supply. A 5 volt power supply may destroy these units. Without 2 amps these units cannot connect to a gsm network.
Cheers
Catweazle NZ
using LM7805 connected to diode 1N4007, i managed to power up this module. but as you can say, i can't access anything related to SIM, such as AT+CNUM command, it will restart the module, i think it related to power shortage.
sahniana:
using LM7805 connected to diode 1N4007, i managed to power up this module. but as you can say, i can't access anything related to SIM, such as AT+CNUM command, it will restart the module, i think it related to power shortage.
7805 is grossly unsuitable for SIM800. SIM800 requires peak current of upto 2A while most 7805 in market these days provide a measly 300-400mA (as compared to theoretical 1A)..
you should try supplying power through a switching regulator like 2576 or LM2596.
Else, buy a SIM800 with onboard voltage regulator. SIM800 is a great GSM Modem and has been used to replace SIM900A by SIMCOM. if you are in India, I can suggest couple of places to buy GSM Online.
Hi guys! How are you connecting the reset pin to the Arduino? I'm using the same module, and I'm afraid to connect the reset of the module to a digital pin of the arduino to control it by software, because of the differences of the voltage. Should I put resistors in between this connection to lower the voltage?
Also is it normal, when I send the command AT+CPOWD to power off, it turns on after some seconds?
Is there a way to turn on the module with AT commands?
I have one SIM800 connected to arduino nano, running for days sending data every hour. I'm using D7 for RESET with no problem. SIM800 is 5V tolerant, no need for level shifting.
One thing about power: first i tested the module with a external power supply regulated to 4.95V with a diode to down voltage to 4.25V. Then i replaced the power supply for a pack of batteries (5.08V), after that i got strange behavior, sometimes SIM800 didn´t send any messages. I figured that at 5.08V, the voltage on the SIM800 was 4.35V that leeds to OVERVOLTAGE warnings. If you use diodes to down voltage, ensure that it stays around 4.2V. Better is to use a LDO or some external power very stable.
About the power on/off question, i use a optocoupler connected to a arduino pin, that way i can use it like a swith to turn on/off the SIM800 module. You can also use a FET transistor to do the same.
Just connect RX/TX from SIM800 to RX/TX arduino (pins 0 and 1), RESET to D7.
Use a 4V external power supply to power SIM800 and don't forget to connect both GROUNDs (power supply and arduino GROUNDs).
geologic:
Just connect RX/TX from SIM800 to RX/TX arduino (pins 0 and 1), RESET to D7.
Use a 4V external power supply to power SIM800 and don't forget to connect both GROUNDs (power supply and arduino GROUNDs).
Thank you, geologic. And can you help me with this changes in SIM800.h?
// change this to the serial UART which SIM800 is attached to
#define SIM_SERIAL Serial1
What must I write in place of "Serial1", or I don't?
Thanks.
geologic:
I have one SIM800 connected to arduino nano, running for days sending data every hour. I'm using D7 for RESET with no problem. SIM800 is 5V tolerant, no need for level shifting.
One thing about power: first i tested the module with a external power supply regulated to 4.95V with a diode to down voltage to 4.25V. Then i replaced the power supply for a pack of batteries (5.08V), after that i got strange behavior, sometimes SIM800 didn´t send any messages. I figured that at 5.08V, the voltage on the SIM800 was 4.35V that leeds to OVERVOLTAGE warnings. If you use diodes to down voltage, ensure that it stays around 4.2V. Better is to use a LDO or some external power very stable.
About the power on/off question, i use a optocoupler connected to a arduino pin, that way i can use it like a swith to turn on/off the SIM800 module. You can also use a FET transistor to do the same.
Thank you, Geologic! It was the exactly answer I was expecting! =]