Sensor Board Programming

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Overview

To program the MSB2 sensor boards we will need the following items:

  • Blue development board (with JTAG header pins on the far left)
  • Atmel AVR JTAG, preferably a USB one
  • Atmel AVR JTAG adapter board (with a rainbow colored ribbon cable)
  • CSR BlueCore JTAG board (with the adapter board plugged in)
  • CSR BlueCore XPSI parallel port cable
  • 2.4GHz antenna
  • Spectrum analyzer (>2.4GHz)
  • A couple USB mini-B cables and the appropriate software/firmware images
  • The MSB2 sensor board you want to program
  • Required Components
  • Development Board

    Development Board

  • Atmel AVR JTAG

    Atmel AVR JTAG

  • Atmel AVR JTAG Adapter cable

    Atmel AVR JTAG Adapter cable

  • BlueCore JTAG Board

    BlueCore JTAG Board

  • BlueCore JTAG Adapter

    BlueCore JTAG Adapter

  • BlueCore XSPI Adapter

    BlueCore XSPI Adapter

  • A spectrum analyzer

    A spectrum analyzer

  • 2.4GHz Antenna

    2.4GHz Antenna

  • MSB2 Sensor Board

    MSB2 Sensor Board

The steps are to:

  1. Plug the MSB2 into the development board
  2. Program the Atmel firmware
  3. Program the Bluetooth radio's firmware
  4. Tune the Bluetooth radio's crystal


Using the Development Board

The jumper, highlighted in red, connects USB power to the plugs and ports on the rest of the board. It should always be removed when removing/inserting boards

The blue development board is designed to provide programming, power, USB serial communication, and debugging capabilities for the iMote1, MSB1, iMote2, MSB2 (all revs), LSB, and BT+SD boards. It provides four sets of connectors (on the left) for iMote2 boards and one set of connectors (on the right) for the iMote1 boards. To use the board:

  1. Plug it in via USB to your computer and install the FTDI USB->Serial drivers (see setting up the FTDI Drivers for help)
  2. Make sure the jumper (indicated on the right) is removed, only the far right green LED should be lit (indicating USB has power)
  3. Plug in the board you want to work with
  4. Then insert the jumper, the green LEDs on the right side should now both be lit



Programming the Atmega128L Firmware

To program the Atmel microprocessor we need to:

  1. Setup our development board, remove the power jumper
  2. Attach the Atmel JTAG to our computer
    • Download and install the AVR Studio software if you haven't already done so (available here atmel.com)
  3. Plug the Atmel JTAG into our development board (see the picture above for the proper orientation of the connector)
    • The flex cable attached to the JTAG's adapter board can sometimes come loose, make sure that it is propperly seated before attempting to program
  4. Take the Atmel JTAG adapter and make sure that the ribbon cable is plugged in the picture below. Then plug the rainbow colored ribbon cable into the development board, making sure it matches the orientation shown below.
    • Adapter board with ribbon cable attached
      Ribbon cable plugged into development board

  5. Next making sure the power jumper is removed and the sensor board is off, we take the adapter board and our sensor board and insert the adapter board into the holes underneath the miniSD card slot on the sensor board.
    • The adapter pins are very delicate so be careful when handling them so they don't bend. If they do bend do not use your fingers to realign them as the pins will break off easily, use a tool and very slowly bend them back into alignment
  6. With the adapter board plugged into the sensor board we need to plug them into the development board, once the board is plugged into the development board we need to make sure the adapter's pins have good contact with the plated holes on the sensor board. We do this by pushing a SD card underneath the adapter board and the unused headers on the development board, there only need to be enough pressure to ensure that the pins are touching the plated holes edges -- be careful to not bend the pins or to force the sensor board out of its slot
    • Adapter and sensor board plugged into development board; an SD card is used to brace the adapter, making sure the adapter's pin make good electrical contact with the sensor board's programming header

  7. Now that our hardware is setup, double check that everything is setup properly and inser the power jumper into the development board
  8. Next start the AVRStudio software. If you have a project for the sensor board already setup select it. Otherwise we need to create a new project for the sensor board. To do this click the Create New Project button, select a project name and output directory hit next, then select the debug platform JTAG ICE and device ATmega128 then hit finish.
    • Click Create New Project
      Next select a name for your project and a destination folder
      Finally select the Debug Platform JTAG ICE and Device ATmega128

  9. With AVR Studio setup we can now program the sensor. To access the program menu click the icon with a microchip with AVR written in it. You can also use Tools->Program AVR->Connect. You should be presented with a menu prompting you for a flash and EEPROM file. Typically you will only need to select a hex file and hit program.
    • However, the first time a board is programmed you will need to set the fuse settings. To do this select the fuse tab, and make sure the check marks match the pictures below. Note: You should never program the lock bits or forget to leave the JTAG programming interface selected. Failing to do so will turn your sensor board into a nice paper weight, until the microprocessor can be removed and replace (with is time consuming and very expensive).
    • Note: It takes AVR Studio a few seconds to read out the fuse settings, before these settings are read into the menu the default selection of checkboxes are set to disable JTAG programming. If you hit program before the fuse settings are read you will immediately disable JTAG programming and will be locked out of the chip! This is quite time consuming and costly to repair so exercise extreme caution when programming these fuses.
    • DevBoard JTAGWin Program.png
      Default fuse settings for most of the fuses
      Scroll down to see the fuse setting for the oscillator

    • If you encounter any errors getting your board to program or connecting to the AVR JTAG be sure to check your connections and try again. If it still fails reconnect the board, turn the AVR JTAG on/off and restart AVR Studio.
  10. Once the firmware has been programmed the sensor board is ready to be used, the only thing left is to setup the Bluetooth radio


Programming the BlueCore3 Firmware

Tuning the Bluetooth Radio

Each BlueCore3 baseband is self calibrated according to the ambient/chip temperature and the input clock. Since the chip takes care of tuning the temperature we just need to set the appropriate tweaking for the crystal, this is set by:

  • the BlueCore radio broadcast an RF signal at what it believes 2.441GHz
  • a spectrum analyzer set to 2.441GHz scanning the RF spectrum for this signal
  • a crystal trim value that adjusts the BlueCore's signal until it outputs a true 2.441Ghz signal

The basic process is:

  1. Program the firmware and persistent store keys on the Bluetooth radio
  2. Determine the crystal trim value (in hexadecimal) using a spectrum analyzer
  3. Convert the hexadecimal number to decimal
  4. Program the converted value into the persistent store keys


Setting up the Spectrum Analyzer

    SpectrumAnalyzerSetup.png

    Any 2.4GHz spectrum analyzer will work the only requirement is it being somewhat calibrated and having an appropriate 2.4GHz antenna. The instructions below are for using a Tekntronix RSA3408A 8GHz digital spectrum analyzer. Here are the steps to setup the spectrum analyzer so you can tune the radio:

    1. With the spectrum analyzer off, plug in the 2.4GHz antenna.
      • This should require no force and doesn’t have to be very tight, be careful to not bend or break any of the delicate leads
    2. Turn on the spectrum analyzer it will boot into Windows XP and after a few moments will start the spectrum analyzer software.
      • It is generally a good idea to leave the system running for about 15minutes before you use it so the device has a chance to warm up and calibrate itself.
    3. First we set the center frequency, by hitting button 3
    4. Enter "2.441" on the keypad
    5. Hit the "GHz" button to indicate that its 2.441GHz
    6. Next we set the span (how wide the visible spectrum is) by hitting button 6
    7. Then we enter "400" on the keyboard
    8. And hit the "kHz" button to indicate a span of 400kHz, in general all the Bluetooth radios should transmit within this span but you can set it lower or higher if needed
    9. Once the radio is transmitting there should be a single peak like the one shown in the figure. By default the purple cursor (seen as a small box on the right side of the peak in the picture) will point to our desired center frequency of 2.441GHz. If you want you can hit the "peak" button to have the cursor highlight what frequency the highest peak is at. In general its better to leave the cursor at 2.441GHz so you don't end up using the wrong center frequency by mistake. You can reset the cursor by entering 2.441GHz in the keypad.



Using BlueTest to get the crystal trim value

    To get the radio to emit a 2.441GHz carrier wave for the spectrum analyzer we need to use the BlueTest3 software to access the Bluetooth radio's RF test modes. We do this with the BlueTest3 program (BlueTest3.exe) which can communicate with the BlueCore chip via the serial port of the SPI interface. To setup the RF test mode and find the right crystal trim values we need to do the following:
    1. Start the software and select the H4 transport, the appropriate serial port (this will be the COM number of the first USB Serial port installed by the development board), and the 921,600 baud rate.
    2. Once you hit ok the software will attempt to communicate with the BlueCore chip, if it fails the software may exit or display an error message. If this happens be sure to check all your connections and ensure that the chip is powered and fully seated in the development board. If the software is able to communicate with the BlueCore chip than the firmware version will be displayed in the bottom console (something similar to 'BC3 (Hardware ID 43) firmware version 4290.'
    3. Once the BlueTest software is up and running we'll first send a command to the BlueCore to have it transmit a carrier wave at 2.441GHz, scroll the "RF Test Modes" box to the "TXSTART" entry and select 'Execute'. At this point a peak should appear on the spectrum analyzer assuming its setup correctly.
    4. With the carrier wave being transmitted we can now tune our crystals settings, to do this we scroll the "RF Test Modes" box to the "CFG XTAL FTRIM" entry and hit execute. So long as we don't do anything else the BlueCore should continue to transmit its 2.441GHz signal so we don't have to set the crystal trim and then execute the TXSTART, it should always be transmitting. Now, we can tune our crystal trim value until the spectrum analyzer shows the peak centered at 2.441GHz. The trim value used here is in hexadecimal so be sure to use the appropriate number when stepping the trim value up and down. After finding the number, write it down and we will have to program the value into the BlueCore using the PSTool.
      Select the H4 Transport, the first serial port installed by the FTDI driver, and 921600 baud
      If the BlueTest software has successfully communicated with the chip it will show the chip ID and firmware version
      We use the default TXSTART settings to transmit a 2.441GHz carrier wave
      Moving the value up should move our center frequency up (to the right) and moving the value down should move the center frequency down (to the left)


Hexadecimal to Decimal Table

    The CFG XTAL FTRIM value is set in hexadecimal, however, the "Crystal Frequency Trim" value is set in decimal. Here's a quick look up table for mapping from hexadecimal to decimal:
    Hexadecimal Decimal Hexadecimal Decimal Hexadecimal Decimal
    0x10 16 0x20 32 0x30 48
    0x11 17 0x21 33 0x31 49
    0x12 18 0x22 34 0x32 50
    0x13 19 0x23 35 0x33 51
    0x14 20 0x24 36 0x34 52
    0x15 21 0x25 37 0x35 53
    0x16 22 0x26 38 0x36 54
    0x17 23 0x27 39 0x37 55
    0x18 24 0x28 40 0x38 56
    0x19 25 0x29 41 0x39 57
    0x1A 26 0x2A 42 0x3A 58
    0x1B 27 0x2B 43 0x3B 59
    0x1C 28 0x2C 44 0x3C 60
    0x1D 29 0x2D 45 0x3D 61
    0x1E 30 0x2E 46 0x3E 62
    0x1F 31 0x2F 47 0x3F 63


Setting the Crystal Trim in the Persistent Store Keys

    Once we've figured out the appropriate crystal frequency trim value, we need to set this value in the chips on-board flash so it uses it each time it boots. To do this we use the PSTool program, which we can access via the serial port:
    1. Even though the interface is slightly different we choose the same settings for the PSTool that we did for the BlueTest software, H4 Transport, the first serial port installed by our USB driver, and 921,600 baud.
    2. Scroll to the "Crystal frequency trim" setting (or use the filter) and set the decimal value of the hexadecimal number found using BlueTest. You can use the above table to make the conversion quicker
      Select the H4 Transport, the first serial port installed by the FTDI driver, and 921600 baud
      Set the decimal value of the hexadecimal number found using BlueTest

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