problem with sim800L module

[ultrasonic.1991]

hi i have a problem with my sim800L module . i connected a 4 volt battery for the supply and i know that it connects to network due to the fact that the network led blinks every 4 seconds. i connected the module to usb to ttl module. i connected rx of sim800L to tx of usb to ttl module and vice versa and i connected the ground to ground. i added a image of my hyper terminal program i changed the baudrate to other values it didnt respond. what is the problem?

 

[BradtheRad]

Which device do you change baud rate on?
Did you change settings for each device, and input a new baud rate? Or, is there any automatic way they know they're supposed to change baud rate?

In addition are other settings identical across the board? Full or half duplex. Parity. Number of bits 7 or 8? Etc.

 

[ultrasonic.1991]

Which device do you change baud rate on?
Did you change settings for each device, and input a new baud rate? Or, is there any automatic way they know they're supposed to change baud rate?

In addition are other settings identical across the board? Full or half duplex. Parity. Number of bits 7 or 8? Etc.

thanks for your reply. by changing the baud-rate I meant changing the baud-rate of the hyper terminal program that I used to interact with sim800L and I attached its photo. I think what you say is about connecting the sim800l to the microcontroller if I'm not mistaking. it is noteworthy to mention that I worked with sim800 and controlled a LED by sending a special SMS without problem. i don't know what is wrong with this sim800L module.

 

[KlausST]

Hi,

Maybe your hardware is not compatible regarding signal voltage levels.
We neither have a schematic nor all datasheets to verify..

Klaus

 

[ultrasonic.1991]

Hi,

Maybe your hardware is not compatible regarding signal voltage levels.
We neither have a schematic nor all datasheets to verify..

Klaus

i attached a photo of my hardware. the usb to ttl module is ch340

 

[KlausST]

Hi,

Is this correct: You want us to look for the datasheets and compare them for you?

Please check valid signal voltage ranges.
Please check that the battery voltage is at valid levels down to microseconds.

Klaus

 

[ultrasonic.1991]

Hi,

Is this correct: You want us to look for the datasheets and compare them for you?

Please check valid signal voltage ranges.
Please check that the battery voltage is at valid levels down to microseconds.

Klaus

no, I don't want you to look in the datasheets. I thought you asked a question and I answered you.
the sim800L datasheet says the voltage level is 3.3 volts. the ch340 datasheet says it works with 3.3 volts so why this doesn't work? the battery voltage is fine. maybe I'm missing something.

 

[KlausST]

Hi,

I thought you asked a question and I answered you.

I still see no datasheet, no schematic, no clarification about logic levels.

No need to be perfect. Paper and pencil is O.K. Saying that you check the levels is O.K. but I don´t see.
I don´t have the time to do this for you. And if you don´t...

Klaus