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! =]
I'm still using another GSM shield with the standard GSM library. I would like to move to SIM800L.
In my current code, I am making an HTTP POST request: I connect to an IP address, then I write the request as text to the connection, including the JSON object, that I want to send to the server residing at that IP, and finally I close the connection.
I didn't see such option with this library. I can only send parameters to the server using URL query arguments. This is indeed an option for me (I'll just change the server code to expect a GET request and read all parameters from the URL), but still - does anyone know of a library for the SIM800(L) that can write to an open HTTP connection?
You can use this SIM800 Library. It works efficiently - BareBoneSim800 Arduino Library and works with any know SIM800 modules. Idea for IoT applications and sending sms.