RoboCup: Redesign 2014-2015

Phase I: Techanical Analysis

The first stage of the 2014-2015 RoboCup redesign involves brainstorming potential upgrades by researching new technologies/resources since the last revision. A parallel analysis of current robot bugs and potential enhancements is also done at this time. Outlined below is a listing of resources that the team used in this brainstorming stage.

Competition 2014 documentation

Team Description Papers (TDP)

Electrical Board Error Logs

Past Electrical Designs

Phase II: Design

During the design phase, specifications are determined for each section of the robot. Experimental results are documented here from all quantitative findings. This phase is also where the high-level ideas from Phase I are tracked to ensure completion.

Logical Controlling Unit

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mbed Debugging

To Do

• Successfully communicate over SPI with a current FPGA and mbed

Completed

• Build development board for testing FPGA configuration from mbed's flash storage
  • Tested and confirmed working
• Obtain mbeds for robot use
  • How: 15 mbeds donated by ECE department

Mechanical/Electrical Integration

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Max PCB Dimensions

To Do

• Research options for using Altium for schematic and board layout designs
  • Contact them for a 30 day trial
• Determine best solution for integrating serial identification to mechanical bases
• Add connection header for ball sensor to control board
• Test motor wire modifications before working on the entire batch of motors
• Determine kicker connections and integration
• Determine options using quarter-turn screws for electrical board attachment

Completed

• Determine location and placement for dribbler motor header
• Update hall connection header to right angled one
• Add pin locations to all connection housings in CAD part files
• Update the 14-pin connection header (female) for the control-to-motor board connection
• Finalize method for adjusting motor wire lengths when motors arrive
  • Decision: Unsolder from motor's PCB, trim to length, and resolder to motor's PCB
  • Reason: Did not want to delay ordering motors any futher & hand soldering results in higher yields compared against hand crimping
• Determine placement of battery location

Radio

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CC1101 C++ library

nRF24L01+ C++ library

Current protocol [LINK TO BE CREATED & UPDATED]

To Do

• Obtain breakout boards for CC1201 transceivers with integrated ANT-916-CHP antenna
• Order numerous CC1201 samples from TI
  • Current quantity: 21
• ?Successfully communicate using two (2) CC1201 transceivers and two (2) mbeds
• Research and determine best steps for structuring radio protocol with primary and seconday frequencies
  • The Crazyflie project has basic radio documentation for how they implemented real-time communication with room for expansion
• Test packet optimizations - Nanopb is promosing for this

Completed

• Successfully communicate using two (2) nRF24L01+ transceivers and two (2) mbeds
  • Result: Task abandoned. Determined that a 2^nd frequency band provided only nominal benefits
• Test methods using breakout boards and compare data rates
  • Result: Packet processing (~60 bytes) for receptions estimated to consume 0.2ms to 0.3ms of processing time @ 60 packets/sec
• Determine optimal secondary frequency for base station updates
  • Decision: End result's data rate is only nominally benefitial for high-throughput broadcasting. No 2^nd transceiver
• Research integration options of the CC1111 and nRF24LU1+
  • Decision: Do not use SoC parts for the base station
  • Reason: Keep radio software on the mbed platform's C++ libraries (SoC would require additional C code for the base station)
• Order five (5) CC1111 transceivers from TI
• Successfully communicate using two (2) CC1101 transceivers and two (2) mbeds
• Obtain breakout boards for CC1101
  • How: Added SMA antenna connector to breakout boards from 2008 fleet
• Obtain breakout boards for nRF24L01+
  • How: eBay

FPGA

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A few minor changes to the FPGA's Verilog code must be made for the 2015 redesign. This includes migrating the [²C] interface with the kicker board to the mbed platform & enhancing encoder connections to support the new differential signals.

Setting up a computer for Verilog development

1. Create an account on Xilinx's website
2. The Xilinx program is called ISE Design Suite (this is on ECE's virtual lab pool computers - can connect to it from anywhere).
   • The desired download link is found under the ISE Design Suite heading
   • The current version at the time of this writing is 14.7 (size: ~6GB)
   • The ISE Design Suite is no longer supported
   • The newer version of Xilinx's software is called Vivado Design Tools, but it does not support the Spartan-3E FPGA
3. Install the program to your computer
   • The installer will prompt you to select an edition to install
     • Select ISE WebPACK
4. Obtain a license at the Xilinx page for license management
   • Open the link sent to you after requesting a license
   • Navigate to the Manage Licenses tab
   • Download the license called ISE WebPACK License
5. Save the downloaded license file to the ~/.Xilinx directory of your computer
   • The program will require you to locate the license's path at first startup

Mandatory user-provided files for Verilog synthesis

• Verilog files(s)
  • Defines the HDL implementation
  • File Extension: .v
• Xilinx Constraint File
  • Defines parameters for correct synthesis to the hardware (pin mappings)
  • File Extension: .ucf

FPGA Commands

Command	Read/Write	Definition
0x00	Read Only	Receive Data Readings
0x01	Read/Write	Set motor speeds

Example SPI Transfer (0x00 Read)

Array Index	Bit(s)	Definition
0	7..0	FPGA Version (0x04 in 2014)
1	7..0	Encoder 1 Count (LSB)
2	7..0	Encoder 1 Count (MSB)
3	7..0	Encoder 2 Count (LSB)
4	7..0	Encoder 2 Count (MSB)
5	7..0	Encoder 3 Count (LSB)
6	7..0	Encoder 3 Count (MSB)
7	7..0	Encoder 4 Count (LSB)
8	7..0	Encoder 4 Count (MSB)
9	7..0	Motor Fault
10	7..0	Kicker Status
11	7..0	Kicker Voltage
12	7..0	Hall Count 1
13	7..0	Hall Count 2
14	7..0	Hall Count 3
15	7..0	Hall Count 4
16	7..0	Hall Count 5

Example SPI Transfer (0x01 Write)

Array Index	Bit(s)	Definition
0	7..0	Packet Type (0x01)
1	7..0	Motor 1 Speed (LSB)
2	7..4	Reserved (Always 0x00)
	3..2	Motor 1 Drive Mode
	1..0	Motor 1 Speed (MSB)
3	7..0	Motor 2 Speed (LSB)
4	7..4	Reserved (Always 0x00)
	3..2	Motor 2 Drive Mode
	1..0	Motor 2 Speed (MSB)
5	7..0	Motor 3 Speed (LSB)
6	7..4	Reserved (Always 0x00)
	3..2	Motor 3 Drive Mode
	1..0	Motor 3 Speed (MSB)
7	7..0	Motor 4 Speed (LSB)
8	7..4	Reserved (Always 0x00)
	3..2	Motor 4 Drive Mode
	0..1	Motor 4 Speed (MSB)
9	7..0	Dribbler Motor Speed (LSB)
10	7	Kicker Charge
	6	Chipper Enable (1=Chip, 0=Kick)
	5..4	Reserved (Always 0)
	3..2	Dribbler Motor Drive Mode
	1..0	Dribbler Motor Speed (MSB)
11	7..0	Kicker Power (<, 0xFF=6ms)

Required Pins

• MOSI
• MISO
• SCK
• nCS
• PROG_B

To Do

• Transition the [²C] bus lines to the microcontroller
• Update Verilog for new differential encoder signals (A+, A-, B+, B-)
  • ( (A+) + (A-) == 0 ) should be true for no errors
• Update Verilog for driving a bootstrap circuit
• Add a writable register for enabling/disabling motor encoders

Completed

• Obtain Spartan-3E development board
  • How: Found a used board on eBay
• Determine required pins for connecting FPGA
  • Documented above
• Document steps for synthesizing Verilog files
  • Documented above
• Successfully configured an FPGA from the mbed's on board flash storage
• Successfully synthesized a Hello World Verilog file using Xilinx's ISE Webtools
• Determine what communications occur over the SPI bus
  • Documented in the tables above
• Finalized that the 2015 motors will use the current FPGA
  • Decision: Xilinx Spartan-3E
  • Reason: FPGA is only used for motor control & no futher capabilities are needed

Motors

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Maxon 50W Custom Motor Drawing

Maxon 50W Motor Datasheet

To Do

• Successfully control one of the new 50W motors with an mbed and Spartan-3E interface
• Modify four (4) of the sample motors to accomidate integration into a prototyped robot
  • Last Task: Place connectors onto the wires for all four (4) motors
• Order motor controller boards
  • Update: Underway
• Test different circuits and document data result set to wiki

Completed

• Order 3 DRV8301 Pre-Drivers from TI
  • Update: Many samples from TI are in the electrical room now
• Finalize the protyping designs of single motor controllers
• Order motors

Motion Sensing & Motion Control

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MPU-9250 C++ library

PID C++ library

To Do

• Integrate the MPU-9250 into the I²C data bus lines from the mbed

Completed

• Order breakout board for MPU-9250

Error Detection & Indication

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To Do

• Determine best solution for controlling the WS2812B RGB LED

Completed

• Order a Bus Pirate
• Order breakout board for RGB LED
• Create breakout board for MCP23017 and place on GitHub repository

Kicker Board & Detection

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To Do

• Create a small microcontroller interface for the kicker board
  • Original Plan: Use a MSP430G2x from TI
  • Updated Plan: Use one of Atmel's ATtiny microcontrollers
    • Why: Much easier to implement a custom ISP with the mbed
      • Can use the Arduino IDE
      • mbed library already exists
• Generate snapshots of the 2011 kicker board graphs for reference
• Use a Serial Identification Chip for unique detection of mechanical bases
• Measure the current from kicker board currently used
  • Data exists for the 2011 kicker board. There is a 2011 kicker board (barebone) equipped with a silicon-controlled rectifier and shunt resistor for capturing oscilliscope data for this. Use a digital oscilliscope and export sampled data for waveform recreation/analysis.
• Update the kicker board to accommodate the new battery's voltage of 18.5V

Completed

• Determine the number of capacitors that will be used
  • Decision: 4

Battery & Power

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The following contains a listing of batteries that were considered for the 2015 design along with other battery/power adapters and accessories.

To Do

• Determine power switch placement and integration
  • Option 1: Use a small switch paired with a relay
  • Option 2: Use standard mechanical switch
• Research switching regular modules
  • OKI-78SR module

Completed

• Change the first switching regulator to accomidate for the higher voltage battery
  • New part number: LM25010
• Finalized the new design's battery selection
  • Result: Zippy Flightmax 2200mAh 5S 40C

Battery Accessories

• Connector: XT60 (Male)
• Connector Lead: XT60 12AWG 10cm
• Charging Cable: XT60 Banana Plug
• Balancing Board: Charge/Balance Board

All Batteries

The following list contains batteries that were considered and known about during the battery selction period. The list is not inclusive.

• Zippy Flightmax 2500mAh 5S 20C
• Zippy Flightmax 1800mAh 5S 40C
• Zippy Compact 2450mAh 5S 35C
• Turnig 2200mAh 5S 30C
• Thunder Power 2000mAh 5S 16C

Phase III: Production

The final phase for creating the new fleet of robots involves outlining the steps and procedures for robot manufacturing and assebly. Future members can use this area as a reference for the fleet's required maintenance. It may also be benefitial for strengthening tolerances in future fleet builds.

Electronics Assembly

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General

• Sparkfun's PCB assembly process
• EEVblog on anti-static bags for component storage

Solder Paste Stencil Creation

SparkFun uses SolderMask, Inc for their stencil needs

• Laser cutting kapton film
  • Material: Kapton Polyimide Film
    • Size: 12" x 12"
    • Thickness: 0.005"
  • Test Equiptment
    • Laser Cutter: Trotec Speedy 300 (140W)
  • Test Results
    • Will not produce required results for making a stencil

• Chemical etching aluminum
  • Untested but very promosing