Interfacing PIC to a USB GSM Modem

[TeleST]

Hey guys,

I am thinking of interfacing PIC18F2550 to a USB GSM Modem (HUAWEI Mobile E1550) to send or receive SMS using AT commands.
Now I know many of you might tell me to stay away from USB interfacing because it is quite complicated. My question is, is it possible?

Anyways, I dug around and I came across a very interesting chip which is FTDI chip (FT231X – Full Speed USB to Full Handshake UART), would this chip make "my life" simpler if I want to head for USB interfacing?

Any help or suggestions will be greatly appreciated

[robosang]

seem to be correct, but no

Because USB have host and device roll. Device cannot communicate with device. USB mouse cannot communicate with USB keyboard, so are USB thumb drives, so does USB printer, etc.... they cannot inter-communicate, they must go through a USB host and normally USB host is computer or laptop. Even the FDTI chip offering USB to UART function, it is meant to offer the UART function for computer not microcontroller.

Yes, there is USB OTG or Host function available on microcontroller, but that is not ready to interface with all type of USB device like your modem, because it require a lot of firmware or software development, which is the driver

[TeleST]

Thank you so much for replying , then what is the use of PIC18F2550 have a USB feature in the first place?

And to further clarify, do you have any other cheap "cost-wise" solution.

And again, appreciate your quite detailed reply

[Brian Griffin]

Thank you so much for replying , then what is the use of PIC18F2550 have a USB feature in the first place?

And to further clarify, do you have any other cheap "cost-wise" solution.

And again, appreciate your quite detailed reply

The PIC18F2250 is a USB peripheral only, not USB host. You cannot connect this to the GSM modem because it is not a host. Some of the higher end PIC24 and PIC32 contains them.

Writing drivers for USB is tedious and requires months of research to get them right. That is why many people tend to use serial connection. There are many GSM modems with serial connection sold in the net.

[TeleST]

Alright, in this case to make my life less complicated I am going to stay way from USB interfacing for the time being.

Honestly speaking, I have interfaced a GSM modem to PIC before and it was quite easy .

The problem is the GSM modem was bulky and expensive and I did not like that at all, so is there any smaller, hopefully cheap, GSM modems that exits in the market.... I am currently thinking of reverting to a simpler choice such as a phone, and many people did recommend me Sony Ericsson phones due to their fairly easy interfacing, do you guys agree with them?