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Firmware Overview

Firmware {#t2016firmware}

Initialization

  • Initialize Kicker(attiny) and FPGA using binary files stored on MBED
    • Compilation for these files is separate from firmware MBED runs
  • Initialize any other devices (radio, MPU, etc.)
  • Start threads

RTOS (Threads)

  • Threads allow us to run multiple segments of code in “parallel”
  • MBED only has one core so only one thread executed at once
  • RTOS is used to control the running of these threads
  • Threads can be running, ready (in queue to be run), or waiting (for some event like a timer or interrupt)

https://developer.mbed.org/media/uploads/emilmont/xthreadstatus.png.pagespeed.ic.c21fE5uss-.jpg

Main

  • Watchdog (reset MBED if it doesn’t go back to main in certain time)
  • Control LEDs (neopixel & LEDs connected to IO Expander)
  • Respond to buttons/switches(rotary selector & dip switch)

Other threads

  • Console
    • Read and write to serial for the console
    • Commands for console defined in commands.cpp
  • Controller
    • Send duty cycles to FPGA to control motor speeds
  • Radio
    • Two RX threads, one TX thread (see Radio section)

Radio

  • How commands are sent to robot (motor speeds, kick, etc.)
  • How information is sent back to the base station (various robot statuses)

CommLink

  • Used as hardware abstraction layer to communicate from higher level firmware to radio hardware (through drivers)
  • What we use to call functions to get/send data through radio
  • Other radio drivers (cc1201 and decawave) are derived from this in order to implement the specific hardware communication
  • Runs RX thread waiting for radio interrupts

CommModule

  • Used to handle packets being sent and received with radio
  • RX/TX queues (as threads) waiting for other threads to put packets in the queue that are ready to be sent or have been received and need to be processed

Shared SPI

  • Allows MBED (master) to communicate with multiple devices through same pins
  • Devices (slaves) currently used are radio, kicker (ATtiny), and FPGA
  • This ensures multiple threads aren’t trying to communicate on these shared lines all at once

Hardfault Handler

  • Written in assembly to call function when the mbed hard faults (crashes)
  • Used to print out information to console useful for debugging

FPGA (verilog)

  • FPGA is programming logic gates which allows for many parallel operations
  • Reads in hall sensors for motors
    • Used to determine which phase to power to keeps motors running
  • Gets encoder values for how fast motor is spinning
    • Given number of encoder steps passed in period of time
    • This value can be read by MBED over SPI
  • Powers correct phases for motors (by sending signals to motor drivers)
    • Powers the next phase after the current phase given by hall sensors
    • Powers the motors using the duty cycle sent from the MBED
      • Adjusting the duty cycle allows us to control motor speeds
  • Acts as SPI slave to receive motor speeds from MBED and has second SPI communication where it acts as SPI master to communicate with motor drivers
  • Pin configurations found in robocup.ucf

Base Station

  • MBED with only radio connected
  • Uses MBED serial lines to communicate with computer running soccer
  • Commands are sent from soccer to base station then to each robot
  • Base station recieves replies back from robots then sends this to soccer