gfwilliams/Greenpower

Telemetry for Greenpower race

Greenpower receiver

https://gfwilliams.github.io/Greenpower/

Wiring

• Wire up a Jolt.js:

JST => Connect to a LiPo battery
Q0 => battery voltage
 sda (blue)   : Potential divider to GND and capacitor from Battery 1 V+ (link wire between batteries)
 scl (yellow) : Potential divider to GND and capacitor from Battery 2 V+ (main 24v voltage)
 gnd (black) : Fan negative
Q1 => battery amps cable
 sda (blue)   : 10k resistor to one side of GND wire from battery to motor controller
 scl (yellow) : 10k resistor to other side of GND wire from battery to motor controller 
   On the Jolt.js side of the resistor, add a 1uF capacitor
 gnd (black) : Fan pin 4 (speed control)
Q2 => temperature sensors (2x DS18B20)
 scl (yellow)  :  DS18B20 data wires https://www.espruino.com/DS18B20 (plus 10k resistor to vcc wire)
 gnd (black) : DS18B20 GND wires
 vcc (red)   : DS18B20 VCC wires
H0 => Throttle control - connect to the middle control wire from the motor speed control via a 10k resistor
      (note that H0 has an internal 2.5k pulldown, which can affect the signal range from the accelerator pedal
      and may stop it reaching 4v = 100%)

Ensure that potential dividers are connected to a read GND on the Jolt.js that can never come disconnected, or the inputs could become over-volted and can destroy the device,

• Connect a fan to the

Software in the car

• Get an Android phone and configure it not to turn off
• On it, point Chrome at https://gfwilliams.github.io/Greenpower/car.html
• get the URL set up (see below) - it should remember
• Click Connect
• Should be done!

Setting up the Spreadsheet

(based on this project)

• Create a new Google Sheet
• Set top row to have the following fields: timestamp V1 V2 V A W throttle lat lon alt speed temp1 temp2 fan
• Extensions -> Apps Script
• Replace myFunction with:

var sheetName = 'Sheet1'
var scriptProp = PropertiesService.getScriptProperties()

function intialSetup () {
  var activeSpreadsheet = SpreadsheetApp.getActiveSpreadsheet()
  scriptProp.setProperty('key', activeSpreadsheet.getId())
}

function doPost (e) {
  var lock = LockService.getScriptLock()
  lock.tryLock(10000)

  try {
    var doc = SpreadsheetApp.openById(scriptProp.getProperty('key'))
    var sheet = doc.getSheetByName(sheetName)

    var headers = sheet.getRange(1, 1, 1, sheet.getLastColumn()).getValues()[0]
    var nextRow = sheet.getLastRow() + 1

    var newRow = headers.map(function(header) {
      return header === 'timestamp' ? new Date() : e.parameter[header]
    })

    sheet.getRange(nextRow, 1, 1, newRow.length).setValues([newRow])

    return ContentService
      .createTextOutput(JSON.stringify({ 'result': 'success', 'row': nextRow }))
      .setMimeType(ContentService.MimeType.JSON)
  }

  catch (e) {
    return ContentService
      .createTextOutput(JSON.stringify({ 'result': 'error', 'error': e }))
      .setMimeType(ContentService.MimeType.JSON)
  }

  finally {
    lock.releaseLock()
  }
}

• Click save()
• Click the run button up top and give it access to everything
• Click Triggers on left
• Add Trigger, then fill in doPost/Head/From spreadsheet,On form submit and Save
• Up top right click Deploy, New Deployment
• Select Web app as type. Call it Greenpower pusher then allow Anyone to use it
• Click Deploy and copy the Web app URL: https://script.google.com/macros/s/......./exec
• Go to https://gfwilliams.github.io/Greenpower/car.html on your phone, tap, set URL and paste the URL in (it might be worth saving the URL in the spreadsheet itself!)

Spreadsheet Extras

You can create a Sheet2 to show the current values.

• In Row 1, paste in your Web API URL (above) just so you remember it
• In Row 2, Col 1, paste in =Sheet1!A1 then drag along to column N to clone (this will copy all column headings)
• In Row 3, Col 1, paste in =CHOOSEROWS(TOCOL(Sheet1!A$3:Sheet1!A$100000,1),-1) then drag along to column N to clone (this formula will copy the value in the last populated column)

Now if you want to add a Gauge:

• Type in a value name, say Speed in one spare cell
• In the cell to a right, press = and click on a value you're interested in
• Now Highlight both cells, and click Insert -> Chart
• Under Chart Editor on the right, click Chart Type and scroll down to Gauge
• Now under Customise, Gauge you can set the range you want for min/max