f-MAC

Implementation of f-MAC algorithm, based on “f-MAC: A Deterministic Media Access Control Protocol Without Time Synchronization” by Utz Roedig, Andre Barroso and Cormac J. Sreenan for Infineon’s TDA5340 TRX and XMC4500/XMC1100 microcontroller.

Usage

Install ARM’s GCC for Linux and clone dependencies (see below). The release 2017q1 is known to work. Edit the Makefile (BOARD=) depending on your target, then run make, which creates a binary in bin/.

While OpenOCD should work in theory, Segger’s JLink tools are usually faster (albeit less stable). For the XMC4500 Relax Kit run:

JLinkGDBServer -select USB=$(USBID) -x foo.jlink -device XMC4500-1024 -if swd -port 3333 -localhostonly 1

The XMC1100 (csmTDA) you can use -device XMC1100-32 instead. Then make gdb starts the GNU debugger. Then load, monitor reset and continue to flash and run the program.

Remote control

Unless several DEBUG_* options in config.h are set, this code will do nothing, unless configured via SPI/UART.

READBUF

Master sends command 01h. Slave responds with one packet from the FIFO.

WRITEBUF

Master sends command 02h, followed by packet data. No response.

READREG

Master sends command 03h and a 8 bit register number (see below). Slave responds with 32 bit register value.

WRITEREG

Master sends command 04h, a 8 bit register number and a 32 bit register value. No response.

Available registers:

RXPENDING: 02h

Number of received packets in FIFO (max 2, see function initFifos)

TXPENDING: 03h

Number of packets waiting to be transmitted (max 2)

CONFIG: 05h

From LSB to MSB, each one byte: Station ID, number of stations, payload size (max 32 bytes)

SPI

SPI uses the configuration parameters CLK_PH=1 and CLK_POL=0. For the correct pinout see the top of spiclient.c. Since response times cannot be guaranteed, the SPI protocol uses to steps. First, hold SS low, then send a request and pull SS high again. After pulling SS low again the code will respond with undefined words until a sync word AAh is received. The actual response follows. Write requests have no response.

UART

UART uses 9600 baud, 8 data bits, 1 stop bit (see spiclientInit) and the same MOSI/MISO pins for communication. At the end of every message (request or response) a break symbol (hold down data line for more cycles than wordlength) must be sent to terminate the message.

Project structure

These files are important, everything else is just boilerplate.

fmac.c

The actual MAC implementation

config.h

A few compile-time configuration options

spiclient.c

SPI and UART slave implementation (disregard the name)

Dependencies are added to src/ as git submodules. These include:

bitbite

Bitstream helper functions

dottedline

8b10b encoding

prettylewis

Hardware abstraction (HAL) for the TDA5340

rtt

SEGGER’s RTT library

xmclib

Infineon’s XMClib