Team 2875 MITiBot Leveraging the HiTechnic Prototype Board for FTC Team MITiBot CT Robot Rally 07 November 2009

Team 2875 MITiBot What You Will Learn You can build many types of sensors that don’t come in the Lego kits. For example: –Rotation sensors for robot arms –Extra switches and knobs to control your robot –Proximity sensors This presentation describes –How the HiTechnic protoboard works –How to build sensors with the protoboard –How to program with protoboard sensors

Team 2875 MITiBot Motivation Last year was rookie season Interested in Electrical Engineering –Mentors with EE backgrounds Interested in basic sensor design –Sponsored by MIT Lincoln Laboratory One of two teams to utilize HiTechnic prototype board –Within MA, CT and Atlanta competitions

Team 2875 MITiBot Configuring Autonomous Modes Red ramp, blue box Blue ramp, red box Two programs Two modes each Half the programming

Team 2875 MITiBot Arm Positioner Potentiometer Potentiometer attached to pivot point on arm Monitors real time position of arm Allows for pinpoint arm monitoring after gearing

Team 2875 MITiBot Motivation ROBOTC drivers were not well supported –Found on Xander Soldaat’s blog –Not official sponsored by Lego, FIRST, or HiTechnic Attempted to become driver developer –Contacted Xander –Contacted HiTechnic –HiTechnic already officially sponsoring Xander’s driver Now available on HiTechnic website!

Team 2875 MITiBot Outline The prototype board Designs with the prototype board Programming the prototype board FTC rules for the prototype board

Team 2875 MITiBot HiTechnic Prototype Board Options Three possible options to purchase –Solderless –Solderable –Experimenters Kit SolderlessExperimenters Kit Solderable

Team 2875 MITiBot Breadboard vs Solderable Bread boarding is great for experiments –Rapidly design and test circuits –Traces are built into the bread board Soldering components allows for permanent installation –Components will not fall off –Usually looks nicer –Traces do not exist

Team 2875 MITiBot HiTechnic Prototype Board Features 1 sensor port NXT voltages (3.3v, 4.3v, 9v, 5v) 6 digital lines –Configure as input or output 5 analog to digital converts –10 bit, 0v – 3.3v –Allows NXT to understand sensor readings

Team 2875 MITiBot Power 3.3v –Most important –Full scale of A/D converters 3.3v 4.3v 9.0v 5.0v GND 4.3v Unregulated 9v –Taken from battery –Can range from 9v – 6v Regulated 5v –Battery 9v regulated to 5v Ground

Team 2875 MITiBot Digital Lines Six digital lines –Can be only on “On” or “Off”, like a switch –Configured for input or output –Each line is configured independently Internal pull-up resistors –no connection = logic HIGH

Team 2875 MITiBot Analog to Digital Converters Five analog to digital converter lines –Can read a range of values 0v – 3.3v operation –makes 3.3v very important –Circuits feeding A/D should use 3.3v for full A/D resolution 10 bit resolution –Counts range from 0 – 1023 –0 counts = 0v input –1023 counts = 3.3v input

Team 2875 MITiBot Magnetic Proximity Sensor Use a magnet as a sensor –Magnet mounted on an arm comes in close proximity to Hall- effect sensor –Hall-effect sensor switches on

Team 2875 MITiBot DIP Switch Robot Control Toggle input of a digital line –Flip a switch of “on” or “off” Reading input with software –Can enable or disable features

Team 2875 MITiBot Rotation Sensor Provides one-to-one positioning –Position remains after power reset –Allows for software limits

Team 2875 MITiBot Trim Potentiometer for shooting power Tune shooting power in real time –Allows power adjustment without changing code Scaling issue –A/D scale is 0 – 1023 –Motor power scale is 0 – 100 Find scaling factor –1023 / 100 = is scale divisor Samples –1023 counts / = –767 counts / = 75.0 –1 count / =.097 What happens with 0 counts?

Team 2875 MITiBot Programming with NXT-G NXT-G –1. sensor port number –2. action (read analog, read or write digital) –3. analog channel number –4. six bit value to output on digital lines –5. six bit control for writing digital lines Setup for output or input –6. output of read analog action –7. output of read digital action

Team 2875 MITiBot Programming with LabView

Team 2875 MITiBot Programming with ROBOTC HTPBreadIO() –Read digital input lines defined by the given bit mask HTPBwriteIO() –Write the value of digital lines defined by the given bit mask HTPBsetupIO() –Configure the lines or input or output –0 = input1 = output HTPBreadADC() –Read the value of the specified analog channel HTPBreadAllADC() –Read the value of all the analog channels HTPBsetSamplingTime() –Set the time between samples –4ms – 100ms range

Team 2875 MITiBot Programming Concepts AddressTypeField 00-07HcharsSensor version number 08-0FHcharsManufacturer 10-17HcharsSensor type 42HbyteA0 upper 8 bits 43HByteA0 lower 2 bits 44HByteA1 upper 8 bits 45HByteA1 lower 2 bits 46HByteA2 upper 8 bits 47HByteA2 lower 2 bits 48HByteA3 upper 8 bits 49HByteA3 lower 2 bits 4AHByteA4 upper 8 bits 4BHByteA4 lower 2 bits 4CHByteDigital inputs (bits 0 – 5) 4DHByteDigital outputs (bits 0 – 5) 4EHByteDigital input/output control (bits 0 – 5) 4FHbyteSampling time Decimal ValuePorts B5B4B3B2B1B Digital line Example: Ports B3 and B0 B3 = 8 B0 = 1 So = 9 is mask used

Team 2875 MITiBot FTC Rules Regarding Prototype Board No external power –Any design is restricted to power on the prototype board Can only connect circuits to the labeled connections Communication must be through NXT connection Sensors can be physically separated from proto-board Additional circuit boards are allowed Prototype board processor cannot be reprogrammed Sensors created cannot cause interference with other sensors or robots Only visible light LED’s may be connected Soldering circuit components is allowed

Team 2875 MITiBot Thank you Team 2875 MITiBot –Programming and assembling demos HiTechnic –Provided many images and concepts Brian Shucker for help assembling ideas for this talk Xander Soldaat –Creator of ROBOTC drivers for HiTechnic parts The Kingswood-Oxford School –Hosting a great event

Team 2875 MITiBot Questions Please feel free to ask any questions Please feel free to share any experiences

Team 2875 MITiBot ROBOTC IR Seeker HTDIRsetDSPMode() –Set the DSP mode of AC carrier wave detector –For FTC we want 1200 Hz (carrier of the IR beacon) –Write a 1 to DSP_MODE register HTDIRreadACDir() –Read the value of the AC direction register HTDIRreadACStrength() –Read the value of one AC sensors HTDIRreadAllACStrength() –Read the value of all 5 AC sensors

Team 2875 MITiBot Protoboard Sensors for IR Beacon The IR Beacon works at 1200 Hz The IR spectrum used is 940nm Need a Photodiode to detect IR signal –Turn IR light into voltage or current Possibly have greater range over IR Seeker V2 We apologize for not having a demo for this