Show pageOld revisionsBacklinksBack to top This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong. ======Introduction ====== **Never did get a picture of this project running** The idea is that an SMS phone can be used to receive SMS messages that can then be displayed on a large format message board. =====What is needed===== ^ Hardware ^ Description ^ | {{devbrd.gif}} | **Atmel AVR Microcontroller Development System**\\ This kit was kindly provided to me by the friendly people over at http://www.btinternet.com/~e2one/avrbrd/ | | {{lcd8x24.gif}} | **8x24 LCD Display** \\ Details of how to wire up a 8x24 display to the development board can be found at http://www.btinternet.com/~e2one/avrbrd/ (see the 8x24 LCD Project). If you use a smaller display then you will have to modifying the code to suit. | | {{7110_main.gif}} | **A mobile phone** \\ I used a NOKIA 7110 but any phone that has a built in modem should be ok. | | {{dlr3.gif}} | **A DLR-3 cable**\\ A phone connector wired to a DB9-F.\\ If you don't have one or you can't afford to buy it then there are some good solutions for making your own | ====The Software==== * As the ATMEL AT90S2313 only has 2k of code space the demo version of [[http://www.mcselec.com/bascom-avr.htm|BASCOM]] can be used without hitting any of its restrictions. * Hyperterminal or any suitable terminal emulation package. Useful for making sure that your GPS unit is tranmitting data. =====RS232 madness===== A great site for the wiring of all things RS232 can found at http://www.lammertbies.nl/comm/cable/RS-232.html {{ 9d.gif }} **9 Pin Connector on a DTE device (Phone connection)** ^ Pin Number ^ Direction of signal: ^ |1 |Carrier Detect (CD) (from DCE) Incoming signal from a modem | |2 |Received Data (RD) Incoming Data from a DCE | |3 |Transmitted Data (TD) Outgoing Data to a DCE | |4 |Data Terminal Ready (DTR) Outgoing handshaking signal | |5 |Signal Ground Common reference voltage | |6 |Data Set Ready (DSR) Incoming handshaking signal | |7 |Request To Send (RTS) Outgoing flow control signal | |8 |Clear To Send (CTS) Incoming flow control signal | |9 |Ring Indicator (RI) (from DCE) Incoming signal from a modem | ====Phone Connector==== {{ pins7110.gif }} **Nokia 7110 DLR-3** ^ Pin ^ Signal ^ Specs ^ |1 |V In | 0..8.5V, 0..850mA | |2 |Chrg Control | PWM, 32..37 Hz, 1..99% | |3 |XMic / Device Selector | | |4 |SGnd / DLR-3 VCC | 3.3 V | |5 |XEar / DLR-3 RTS | | |6 |MBus | 9600bps | |7 |FBus Rx / Modem | 9600 - 230.400 bps\\ < 0.8V : '0'\\ > 2.0V : '1' | |8 |FBus Tx / Modem | 9600 - 230.400 bps\\ < 0.8V : '0' @ max. 4mA > 1.7V : '1' @ max. 4mA | |9 |LGnd | | ====Inside the AVR cable==== The standard cable that is supplied with the AVR development kit uses a 3 pin configuration for RS232 data. It is wired as a DTE with built in loop back handshaking. {{ avr232db9.gif }} **AVR RS232 DB9 wiring** The DLR-3 cable expects partial handshaking from a DCE. The problem is the AVR board does not implement any hardware handshaking and is wired as a DTE. ====AVR/DLR-3 cable==== To overcome this problem we will build a new cable. This will be wired so that the AVR board is seen as DCE, additionally it will also have a hardwired active DTR signal. {{ db9_avr.png }} ^AVR board IDC ^Connector ^ Function ^ |1 |5 |Signal ground | |2 |3 |Tx -> Rx | |3 |2 |Rx -> Tx | |4 |4 |Vcc -> DTR | {{ db9_avr_photo.jpg }} The purpose of this null modem cable is to make the phone think there is a DCE device listening {{tag>avr}} atmel/smsrx.txt Last modified: 2012/07/09 11:43by minerva9