FBus

Fbus (for "Fast Bus") is an ANSI/IEEE data bus oriented towards backplanes and cell phones. The standard specifies a way for various pieces of electronic hardware to communicate, typically with one piece acting as master (sending a request), and another acting as a slave (returning an answer). The F-Bus is a bi-directional full-duplex serial type bus running at 115,200 bit/s, 8 data bits, no parity, one stop bit. Much like a standard RS-232 serial port, F-Bus connections uses one pin for data transmit and one pin for data receive and for ground.

The Fastbus standard specifies completely the size, power requirements, signalling levels, and communications protocols for boards that live in a Fastbus crate, which is also a part of the specification.

Uses

At CLEO, the LeCroy TDCs used in the CC, DR, and MU are Fastbus compliant, and as such, live in Fastbus crates. Often the term Fastbus is used to refer to the set of crates or boards as a whole, or even to refer to the readout code that talks to the TDCs [http://www.lns.cornell.edu/~tom/cleoiii/CC/glossary.html] .

Interfacing with a cell phone

Most Nokia phones have F-Bus and M-Bus connections that can be used to connect a phone to a PC or a microcontroller. The connection can be used for controlling just about all functions of the phone, including sending and receiving SMS messages, making calls, as well as uploading new firmware etc [http://www.embedtronics.com/nokia/fbus.html#part1] .

The Fastbus connection on a cell phone can be interfaced with an RS232 serial port by building a custom cable. The serial cable contains electronics for level conversion and therefore requires power. Power must be supplied to the cable electronics and this is done by setting the DTR (Data Terminal Ready) pin and clearing the RTS (Request to Send) pin. The DTR pin is connected to a +3 to 12 Volt supply and RTS to a -3 to -12Volt supply. The easy way to achieve this is by using a Max232 or similar transceiver for the RS232 TX and RX pins and then connecting the DTR pin on the serial cable to the V+ pin on the Max232. The same is done for the RTS, however it is connected to the V- pin on the Max232. The V+ and V- pins are derived from internal charge pumps that double the input voltage. ie. for a 5V Max232, the V+ will +10V and the V- will be -10V.

The next step is to synchronize the UART in the phone with the PC or microcontroller. This is done by sending a string of 0x55 or 'U' 128 times. The bus is now ready to be used for sending frames.

References

* [http://www.lns.cornell.edu/~tom/cleoiii/CC/glossary.html Glossary of Calorimeter Jargon]
* [http://www.embedtronics.com/nokia/fbus.html#part1 A Introduction to Nokia F-Bus]