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:)Hardware:
- 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.Construction bugs
- NOT YET FIXED IN SCHEMA/PCB
- 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.ToDo
More pictures in the gallery
- RTC trimming
- Voltage logger to CSV files on SD card
- USB connectivity
- Text and image file browser