General purpose RF receiver


Posted on Feb 6, 2014

A sensor project which transmits it`s measurements via a 433Mhz wireless communication link. On this page I will describe the details of my self built receiver which receives data from this sensor. To build a general purpose RF receiver module which receives messages from a 433 Mhz wireless link (for example from my self built RF sensor )and forward the received and decoded message to my


General purpose RF receiver
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Linux server via USB, where they are further processed. For the USB interface, I`ll be FTDI`s TTL-to-USB cable, which is a ready-to-use solution for briding 5V TTL signals to RS232 emulation over USB. This enables the microcontroller talk directly to the linux box without any additional components. The linux kernel supports the FTDI chip, so it works out of the box. When this cable is plugged in, the RS232 port is reachable via /dev/ttyUSB0. For debugging purposes and possible other future features, the receiver module will be able to write to a HD44780 compatible display (I`ll be using the EAW162B-N3LW) which is attached using a 14 channel flat cable For the main processor, a PIC16F690 microcontroller will be used, which has a built-in crystal/clock and enough pins to support all interfaces described above. For re-programming the firmware of the microcontroller without needing to remove the chip from the board, I`ll be using ICSP (In-Circuit Serial Programming) All messages which this receiver module should be able to receive are encoded in my own RF protocol. This protocol is a kind of Ethernet protocol, it contains a destination address field, a source address field a message length and a checksum field. This protocol does not say anything about the kind of content which it carries. The syntax looks as follows: When transmitted over RF; the message is encoded using Manchester encoding which is a self-clocking signal...




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