Guidance for Interface SIM 800c with Arduino


#1

Hello!

After having busted many SIM modules, I finally bought a generic Sim 800c module and would love to know how to interface it with an Arduino Nano (or Uno). Would also like to know the power supply I should provide as the board also has a 5V pin on it. An image of my module is below:

Thanks a Million!


#2

Hi,
Whats on other side of the board? Do you have a 4V regulator on the other side.?
If you have 4V regulator which converts the 5V input to 4V then you can connect 5V and run the device. The end goal is to have 3.8V to 4V on the VBATT pins of the module. Apart from that, make sure there are IO level translators on board this module to connect to 5V MCU UART lines… If not you will need level translation.

The best place to look is manufacturers manual or documentation stating the above power supply specs and IO level specs


#3

Hey Ravi!

Thanks for the reply! No I don’t think there are any regulators on the other side of the board. There is a SIM card slot on the other side nothing else. I will be making use of a DC-DC buck converter to supple the required current. As for the UART lines, just to be on the safe side, I am planning to use a logic converter.

My main problem is that I’m having a hard time identifying which connection goes where. There is a V_BAT pin, a 5v pin and a V_TTL pin. I recently came across this image for hooking up this module. Would love to know if this is the right way to connect it.


#4

Looks ok except these. :
The MCU IO level should be <3V or it will damange UART lines if no level translation is used.
TX of MCU to RX of module and
RX of MCU to TX of module
Use shorter thicker wires to power the module from power source or current wont be enough.


#5

I’m using a Bi-directional Logic Converter with 3.3v. Will it be fine, or do i need to provide Strictly <3v


#6

I am using the same module with 5v psu and no level converters. The module works fine.
I think there is much confusing advice about the SIM800C because some data refers to SIM800C devices and other sites refer to modules with the SIM800C device on a module. Some boards have a 4v regulator so you can use the 5v while others do not have the regulator and quote “running the SIM800C at 5v will damage the device”. Naturally nobody wants to blow the device up so they heed the warning and try to run it at 3.3v or 4v. The answer is to check what you have bought. If you have bought a SIM800C device then use 4v max but if it is on a module it MAY work on 5v. Read the specification on YOUR device.


#7

I agree with @pigman