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Hi, How to interface this module to MCU. I like to send data in a SMS form. Is it necessary to use all control lines (RTS, DTR...) Velja |
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Motorola D15 GSM data Module
Started by ●August 19, 2004
Reply by ●August 19, 20042004-08-19
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At 2004-08-19 13:21, velja_c wrote: >How to interface this module to MCU. I like to send data in a SMS >form. Is it necessary to use all control lines (RTS, DTR...) Don't you have a datasheet? ;-) Generally when communicating serially you don't need to use handshake signals when the receiver is always faster than the sender. Instead of using hardware handshake you can also use software handshake, when both sides understand it. It's usual to use Xon and Xoff (0x11 and 0x13 or ^q and ^s) to enable and disable the opposite streams. So when I send you an Xoff you have to stop sending within a couple of bytes and wait for an Xon from my site. Generally the receiver had an inputbuffer of say 16 bytes and when a threshold was reached an Xon or Xoff code was send, so at say 4 an Xon and at 12 an Xoff. Please note that these codes themselves should not be buffered but should have priority over the buffered data. In general applications we would combine the hard and software handshaking, so we would also switch the hardware handshake line together with the Xon and Xoff (but the latter would be optional). Also note that reserving these ASCII codes for the handshaking process makes it harder to transmit whatever code you want over the line (like binary data). You will either have to use some sort of escape mechanism (character doubling for example or an escape character) or use ASCII-encoded binaries (using UUENCODE, MIME, BINHEX etc.). Greetings, Jaap -- Chip Directory -- http://www.chipdir.biz/ -- http://www.chipdir.info/ -- http://www.chipdir.net/ -- http://www.chipdir.nl/ -- http://www.chipdir.org/ -- And about 30 other mirror sites world-wide. -- -- To subscribe to a free 'chip issues, questions and answers' -- mailing list, send a message to with -- in the body 'subscribe chipdir-L'. About 500 experts are -- willing to think with you about electronics problems etc. |
Reply by ●August 20, 20042004-08-20
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----- Original Message ----- From: "Jaap van Ganswijk" <> To: <> Sent: Friday, August 20, 2004 5:55 AM Subject: Re: [m68HC11] Motorola D15 GSM data Module > At 2004-08-19 13:21, velja_c wrote: > >How to interface this module to MCU. I like to send data in a SMS > >form. Is it necessary to use all control lines (RTS, DTR...) > > Don't you have a datasheet? ;-) Yes, but there is explanation only for connection to COM port of PC I think that I can connect some pin to GND or VCC or something like this to avoid using all those lines. When I use only Rx and Tx without other lines connected I don't receive anything from GSM module. I want to see return from modem like OK or ERROR or BUSY .... Velja |
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Reply by ●August 21, 20042004-08-21
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On Sat, 2004-08-21 at 05:03, Velja wrote: >> Don't you have a datasheet? ;-) > Yes, but there is explanation only for connection to COM port of PC It doesn't come much more basic than that! > I want to see return from modem like OK or ERROR or BUSY ... Well, either the module is programmed to do that, or it isn't. If you can post a URL for the datasheet, one or two of us will take a look ... (Won't we?) -- Cheers, Paul B. |
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Reply by ●August 22, 20042004-08-22
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--- In , "Paul B. Webster" <paulb@m...> wrote: > On Sat, 2004-08-21 at 05:03, Velja wrote: > >> Don't you have a datasheet? ;-) > > Yes, but there is explanation only for connection to COM port of > PC > >> It doesn't come much more basic than that! > > I want to see return from modem like OK or ERROR or BUSY ... > >> Well, either the module is programmed to do that, or it isn't. >> >> If you can post a URL for the datasheet, one or two of us will >> take a look ... (Won't we?) >> -- >> Cheers, >> Paul B. I second Paul's advice - we really need to have more info on the module you are using before we can offer you any meaningful advice. From what little info you have provided, it is hard to say whether or not you need to 'respect' (monitor/control) the hardware handshaking lines such as RTS/CTS/DSR/DTR. There is also no way for us to know whether the module looks like a smartmodem and uses AT- style commands and modem responses, or if it uses some other sort of command protocol (if any). Let us know who makes the module, and what its part/model number is, and provide a link to the mfr's website. We cannot help you unless you help us by providing the technical information (or links to it) that we need. You have stated that it is a 'Motorola D15 GSM data module' but this is not sufficient detail for us to find more info or offer interfacing and programming advice. One thing I can say at this point is that you will (probably) need to use a RS232 level-translation device, such as a MAX232/202 or perhaps a MAX208 or equivalent part to convert the device's RS232 signal levels (which range from approx. -9V to +9V typically) to logic-level (0 to +5V) signals that the HC11 uses. This definitely applies if the device you are using is designed to connect directly to a PC COM port, as you stated previously. |
