James

Pinewood Derby Mars Rover

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Feb 182012
Pinewood Derby Mars Rover

Pinewood Derby Mars Rover

Hey Pinewood Derby Race Fans!

Need an idea for this coming Pinewood season?  Have a look at our Mars Rover from the 2012 race season.  I’m proud to announce we won first place for the “People’s Choice” award.  Good thing too, this car design is not the fastest car on the track.

The three blinky LED lights are all hacked from other sources.  The big dish on top came from K Mart.  The dish was a sphere before we broke it open.  It was originally designed to float in a fruit punch bowl.  K Mart sold them as a pair for $5 bucks.

The two tail lamps were tea LED lights.  Bought these in the grocery – these can be had for around 30 cents each.  We hacked them down and be smaller then the originals.  The on/off switch also got reworked so that it now accessible along the back edge.  Otherwise, the switch points out of the bottom of the lamp.

The top deck is covered in aluminum foil.  The bottom chassis is covered in copper tape.  The copper tape was some 1″ sticky tape I’ve had forever, and a day.  The two covering gave the car a nice two tone look.  Note, the middle wheel is non-functional and is mounted a full 1/4″ above the track.

Well, hope this give you some more ideas for you next car.  If so, post some comments below.

 

Continue reading »

Posted by James at 5:58 pm

Running FreeRTOS Demo within TrueSTUDIO

Copper, EPS - Electric Power Steering 11 Responses »
Jan 062012
Atollic TrueSTUDIO Lite

Atollic TrueSTUDIO Lite

This posting is how-to for getting FreeRTOS running inside of TrueSTUDIO using my demo code.

My TrueSTUDIO installation is goofy because I’m running TrueSTUDIO inside a VMWare virtual Windows XP machine.  My host machine is Ubuntu 11.xx and I can report the STM32F4 Discovery board USB drivers, passing through to VMWare / Windows, and work just fine.  With this setup, I can do all my editing using GVim on the Linux side and my compiling and debug on the Windows side.  Strange but true – works for me.

So, to straiten out the project setting takes just a couple of changes.  No big deal.  The jpg images below should be all you needed to setup the project on your machine, however you have your machine setup. Continue reading »

Posted by James at 12:57 pm

STM32F4 + FreeRTOS + TRUEStudio = Awesome-O

Copper, EPS - Electric Power Steering 8 Responses »
Jan 052012
STM32F4 Discovery

STM32F4 Discovery

ST Micro really gave the world a nice Holiday present this year by releasing the STM32F4 Discovery board!  You can get yours at Mouser for $16.25.  An amazing dev. board for $16.25.

  • 32-bit ARM Cortex-M4F Core
  • 1MB Flash, 192KB RAM
  • FPU (Float Point Unit), 16-Channel DMA
  • Ethernet MAC 10/100
  • USB 2.0 OTG HS/FS
  • 6x UART (LIN, Strtacard, IrDA)
  • 3x SPI, 2x I2S, 3x I2C, 2x CAN 2.0 B
  • 3x 12Bit ADC (24 Channels 2.44MSPS), 2x 2-Channel 12-Bit DAC
  • 2x 16-Bit Motor Control PWM, 10x 16-Bit Timers, 2x 32-Bit Timers

Discovery Board Extras:

  • ST MEMS motion sensor (LIS302DL 3-axis digital accelerometer)
  • ST MEMS audio sensor (MP45DT02 omni-directional digital microphone)
  • Audio DAC with integrated class D speaker driver (CS43L22)

Continue reading »

Posted by James at 9:42 pm Tagged with: , ,

Hacking “Holiday Living” Tea Lights

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Dec 312011
LED Tealight

Holiday Living LED Tealight

Just goofing around today with all my Xmas stuff.  Thought this might be interesting to someone.

Have you ever wondered what makes one of these LED lamps flicker? I did too.  So, one of the lamps had to volunteer to be opened up for a little closer inspection.

I was shocked at the simplicity of the lamp.  One CR2032 coin cell battery keeps the lamp flickering for hours.  Saying the lamp is flickering is a stretch.  Seems more likely the lamp is randomly jumping between half a dozen set PWM values.  Still, how do they do that?  There is just the battery, a switch, and an amber LED.  How does the LED flicker at all?

Well, turns out, the LED has a tiny ASIC built right into the plastic of the LED.  The tiny ASIC is “encapsulated” into the LED itself.

Below are a some more closeup pictures of the LED.  I took these pictures by holding my little camera up to the eye piece of my microscope. Continue reading »

Posted by James at 4:21 pm Tagged with: , , ,

EPS – Magnet Encoder Reverse Engineering

EPS - Electric Power Steering No Responses »
Dec 162011
EPS Encoder Probing

EPS Magnetic Encoder Probing

Very Cool!  The encoder works as expected.

After tracing the encoder signals back to the ASIC, I was able to use the LSA to easily probe the signals coming from the encoder board.  Well, I shouldn’t say easily because is was tough to get the grabbers on the ASIC pins without shorting them together.  In fact, on my first attempt I did have a pair of pins shorted together.  However, once the short condition was removed, the ECU didn’t seem to suffer.

The encoder signals make sense for a three phase BLDC motor application.  Have a look at the following LSA plot to see the five digital signals coming from the encoder board.  Note, the encoder board is bolted on the back of the motor.  See my previous post for pictures of the encoder board. Continue reading »

Posted by James at 4:32 pm Tagged with: , , ,
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