Geeky specs
Reblogged from minestation
The Minestation is a standard Arduino shield. It has:
- Nokia 6100 LCD color 132x132 16bit.
- Booster step-up for the LCD.
- 74HCT245 as a voltage level adaptor 5V/3,3V.
- Two push buttons for the Arduino external INT.
Booster
The Nokia 6100 LCD needs of a supply voltage for backlight leds around 7V. There’re several types of shields that raise the 5V of the Arduino’s power supply based on Motorola MC34063, but involving the use of 10 external components (or more) in addition to the chip itself.
We found a simple solution using the Linear Technology’s LT3465AES in a encapsulated TSOP23-6 and using only four tiny components, without the needs of oversized tantalum capacitors:
The result is a voltage around 6,8V-6,9V without loss on the inductor and better performance than MC34063.
Level adaptor
Another inconvenience that we solved was about the adaptation between the LCD level voltage (3.3V) and Arduino (5V). We used a 74HCT245 (it works really well at its inputs to 5V high while its powered by 3.3V). This eliminates the voltage divider networks using Zener diodes and resistors, making easier the assembling process.
Buttons
Finally, we added two push buttons to change the values of the contrast of the display because not every display shares the same amount of brightness with the same internal values of contrast.
These push buttons are wired to the Arduino D2 and D3. They’re the only external inputs that allows to be monitored by a required INT that avoids to enter in a crazy read loop caused by the push buttons (this means a constant that will reduce cycles of the already exhausted Arduino)
