Mar 142012
 
Chicago Electric Cordless Screwdriver

Chicago Electric Cordless Screwdriver

OK, I admit it, I thought I couldn’t go wrong buying a $10 dollar cordless screwdriver.  Yeah, nice idea – but not so much.  My backup plan, in case the screwdriver really stunk, was to adapt the parts into a robot drive motor.  As a robot wheel drive this screwdriver might not be a bad buy.

As a power screwdriver this model kinda stinks.  It’s rated at 4.8 Volts / 180 RPM and comes with a 6V / 300mA charger.  The motor / gearbox does not generate a lot of torque.  However, the worst aspect of the screwdriver is the charger.  Both the charger and the screwdriver get very warm after a day on charge.  Not good.  In other words, you can’t just leave the screwdriver on charge for days on end.  What a waste of energy!

HFT Screwdriver

$10 HFT 4.8V Screwdriver

Given the screwdriver stunk as a screwdriver, it only seemed right and OK to rip apart the brand new screwdriver to see if option B was going to work.  Below are some findings from the teardown:

  • Of course, the batteries are cheap-o Ni-Cd 600 mAh.
  • The gearbox, which is a nice planetary two-stage, needs to be mounted in the case to stay together.  Without the case screws, there is nothing holding the motor and gearbox together.
  • To use the motor / gearbox in a robot much of the original housing around the motor and gearbox would need to remain.  The housing would be needed to hold the motor and gearbox together.
  • While the front of the screwdriver looks made of metal, it is not.  The gearbox is all plastic except for the sun gear on the motor.
  • Testing the motor on my power supply I found the motor does not even start to try to turn until 1 amp of current is flowing!  Not the most efficient motor / gearbox combo.  After a little break in, I found the minimum motor speed / current was 1/2 Volt and 1/2 Amp.  So, just to free-wheel, the motor / gearbox consume a 1/4 Watt of energy.  Not great.

So, bottom line, not the best choice for either option A or option B.  In hindsight, I should have known that a $10 cordless screwdriver was going to stink!

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 »


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 »

Jun 032011
 
AX-12A

AX-12A

Based on a project I have in mind I started playing around with the AX-12A servo motor from Robotis (a Japanese company).  The AX-12A is a newer version of the old AX-12+ servo motor.  It’s my understanding that the 12A is just a redesign of the plastics – the electronics are the same between the two versions.  Still, the naming the new version 12A is confusing to this English speaker.  Should have called the new version “++”.

Anyway, below is stuff about connecting a AX-12+ to your mbed development board. Continue reading »

Apr 132011
 

LCD

Well, I had big plan for this LCD thing.  After many many hours I’m calling Uncle!  I give.  The plan was to have this blue LCD floating on a wire stalk above the STM32 Discover board.  There is just one problem, the display is almost translucent so things behind the display make it hard to see what’s being display on the screen.  What’s needed is a white background – preferably a background that is also generating light.  You know, a LED back-light.

For more on the LCD hardware have a look at this link where I covered info about the display.

Continue reading »


Mar 062011
 

The Sparkfun LCD is OK – but, it seems really old (surplus).  So, I went looking for something new (but similar).  Ultimately, I found something interesting at Mouser from a company called Electronic Assembly.  Seems they have taken a COG (chip on glass) display and fused PCB legs onto it.  The price also helped – only $12 bucks.  The displays are monochrome and have a graphic format of 102×64 pixels.  The displays are designed to interface to a micro using a SPI bus.  Note, these version of displays that use a SPI interface are read only.  The display has no MISO pin to allow the display to be read.  The Sparkfun / Nokia 5110 display was the same – no MISO pin.

Continue reading »

Feb 272011
 

Copper LCD

Very exciting, very exciting!  Nothing better than getting an LCD display working for the first time.  Makes one feel like the captain of the universe.

The rest of this post describes interfacing a Nokia 5110 LCD display to the STM32 Discovery board.

Continue reading »

Feb 122011
 

Copper gets Debug & LED PWM

OK, it’s been a long week – seems like a lot of effort to get a silly serial port and PWM channel working.  Still, I can see lots of promise in this little board.  In fact, the more I pour over the datasheets the more impressed I become with the STM32 Arm micro.

Remember, Copper is short for “Cheap-O Programmable Pint-sized Educational Robot”.

Continue reading »

 Posted by at 1:49 am

Feb 082011
 

FreeRTOS

Adding FreeRTOS to COPPER

Hey kids, today I give you BIG guns. I had a college professor tells us one day that, “today I give you big guns!”  I think he was teaching teaching us something good like mesh circuit analysis.

FreeRTOS is a very big gun in the embedded software world!

Continue reading »

Oct 152010
 

ST Discovery Board

Copper = Cheap-O Programmable Pint-sized Educational Robot

What the world needs now is – a Cheap-O Programmable Pint-size Educational Robot (copper for short).  OK, maybe the acronym doesn’t work that well.  Good enough for now?  Maybe one of you will suggest something better!

Here comes COPPER to save the day!

The goal / intent is to design a robot with a price point of $25
bucks!  Yep, that’s right, a $25 dollar robot.  At $25 bucks it’s a no
brainer for the parents. I want to have a robot design that each, and every, kid can afford.

Continue reading »

 Posted by at 1:00 am
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