Connect SIM800L and AT&T Chip to the Cellular Network

[Programmer I+D]

First I am in Mexico. I want to connect the SIM800L module to the cellular network to be able to make HTTP requests with GET and POST, I have an AT&T chip. But I can't perform the initial configuration, these are my commands.

AT + SAPBR = 3.1, "CONTYPE", "GPRS"

AT + SAPBR = 3.1, "APN", "INTERNET"

AT + SAPBR = 1.1

AT + SAPBR = 2.1

AT + CLTS = 1

I hope you can help me, or comment if someone has managed to communicate for HTTP.

Thanks and regards

[asmallri]

[Programmer I+D]

Thanks "asmallri":

I had read something about it, but I had no idea what you mentioned. So, in order to use a SIM module in the US, what model do you suggest? And with what company?

I am thinking of using a SIM7000G Module with AT&T or T-Mobile.

Thanks and Regards

[asmallri]

I cannot recommend one module over another but you need to be looking for a module that supports LTE (4G) or at least 3G.
_________________
Regards, Andrew

http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!!

[temtronic]

As for a carrier, I'd think you'd use your cellphone carrier ?

[benoitstjean]

If I can be of any help, I had started many years ago with the SIM900 and decided to jump to the SIM5320 (3G) for many reasons, one being that the SIM900 was only 2G. For the past year, I use the SIM7600 (LTE) and phasing-out my SIM5320 products. The 2G modems don't work anymore in Canada and 3G is being phased-out. Also, the data rate on the SIM800 is slow so trying to load web pages will throw you back 25 years at the age of dial-up internet.

The few commands you provided does not indicate any sign of successful initialization of the modem. You can't try to post a webpage using the modem unless you are successfully connected to the network.... so start with that first.

The SIMCOM modems are great reliable products but you may struggle with getting support and their documentation is quite awful, trust me on that. They have made progress over the years but still, it contains lots of "chinglish" with sentences that don't make sense and lack of details. But I can guarantee you that when you get it to work, it works very well and it's quite stable.

Problem though is that this forum is for PIC devices and you haven't specified which PIC you are using.

I am using an PIC24EP512GP806 running off a 29.4912 MHz oscillator overclocked at 129.024 MHZ. That clock is the fastest I can go that will also be able to provide other clocks as PWM signals (3.072MHz and 128kHz) for other devices tied to the modem and 115200bps between the PIC and modem.

I strongly suggest you use DMA for serial transmission and buffer all incoming serial data to a queue and process the data later. The modem works in an <AT command --> response> scheme so you send it an AT command and it returns a formatted response.

Anyhow, before you start anything, start-off by writing code that will initialize your modem. Once you can make and place calls or send and receive SMS messages, then jump to the data portion. That's a whole other ballgame.

Are you using a PIC device?

Good luck.

Ben

[Programmer I+D]

Thanks "benoitstjean":

I have bought the SIM7000G Module and I plan to use it instead of the SIM800L, can you tell me a help link or some code example for the SIM7000 series since it is the first time I use it and how do you mention the datasheets that can be downloaded from the SIMCOM website are a bit confusing. By the way for this project I am using a PIC18F45K50 and I have already been able to make calls and send messages from SIM800L.

Thanks and Regards

[newguy]

[benoitstjean]

No problem for the help. I don't have any links for you unfortunately, all datasheets must be downloaded on the SIMCOM website directly. Just create yourself an account: < http://www.simcom.com/member/login.php?lang=en >

You may find some online but it is most likely outdated.

I also don't have any links to code because I wrote everything myself from scratch.

If you can do calls and send SMS, then that's a good start.

I strongly suggest you invest, if you have the money, in something like a USB to TTL SERIAL cable (from FTDI available at on DigiKey website) for around 30$ CAD (22$ USD). Grab the one with the TTL voltage matching your MCU's voltage. You connect the TTL end to your PIC's TX/RX pins and the USB side to your PC. Install a free terminal program like Tera Term then you can communicate with your PIC.

Then you can have also a standard USB cable tied to the modem's USB and launch a secondary console tied to the modem. Now, you will have two serial consoles, one to monitor your MCU and one to send and receive AT commands to the modem.

From this point, you can try commands straight from the serial console to the modem and see the outcome. When all this works, apply what you learned to your PIC so that it mimics what you do.

Hope this helps. I don't have the SIM7000 so I don't know what it can or cannot do.

Ben

[Programmer I+D]

Thanks "benoitstjean":

I already have a SIMCOM account, I also have the USB to TTL SERIAL converters. I will put aside the SIM800L and start with the SIM7000G from scratch.

Thanks and Regards

[benoitstjean]

Alright! Good luck!