Thursday, Feb 2, 2012| Tags: lib

MicroCmd is a small battery-operated pocket device. This is the first time I used ARM LM3S5632 chip in my construction - there’s nothing to be afraid of as I figured out:)


  • Nokia 3310 LCD
  • 3 axis I2C accelerometer
  • microSD slot
  • mini USB connector
  • battery charger circuit
  • PlayStation Portable 2 axis analog “joystick”
  • IR LED diode to rule all IR devices at home :)

.. and.. that’s it! :) All that was squeezed to small area 59×38mm. The 2 layer boards will be maufactured by Pool Service in fab house in my country.


More pictures in the gallery

Construction bugs


  • LCD connector is mirrored, but it could be fixed by using wires and rotating it by 90 degrees. I had to do some framebuffer and software rotating because there’s not hardware support for drawing data upside down. But now I see that this layout of LCD is more suitable because the visible area of LCD is starting right of the top of the device.
  • Accelerometer’s footprint has smaller pin pitch :( So no accelerometer on these boards :( The good news is that the soldering of this package it’s not so hard as I thought. The only thing you have to do is prepare some sort of heat holes under the chip to the opposite side of the PCB.
  • Ordered 2,5V step-down DC/DC converter instead of 3.3 V, so I had to do some voltage divider circuit, but fixed :)
  • There’s some Errata in the RTC of the LM3S5632 so I had to route wire from external crystal also to the RTC clock input, this could count seconds but I have no idea how precise this will be.
  • There’s missing capacitor near the voltage input for Li-Ion charger chip. After small reworking charging works.

Ok, now view from the other side - what is working now in software & hardware?:

  • LCD with frame buffer & Joystick
  • Deep Sleep mode - consumption it’s not perfect but I can live with 4mA right now.
  • Timed wake-up useful for logging
  • Access to SD card
  • SD card file browser
  • IR transmitter
  • Battery charging

Now I have to focus to tweak the hardware and low level software, the I create some nokia-like snake game, later IR remote control and some sort of USB device.


  • RTC trimming
  • Voltage logger to CSV files on SD card
  • USB connectivity
  • Text and image file browser