AriCalculator is a home made pocket calculator.

[hotwolf]

Alejandro,

The AriCalculator's CPU runs at 50MHz using the S12G's PLL and internal RC oscillator as reference clock. The MCU's run current is below 17mA. The clocks can be turned of when the device is idle and the USB port is unplugged, reducing the current consumption to about 25uA. The calculator can be then woken up through the keyboard, even when the system clocks are stopped. The display draws 320uA in operation, but can be put in a low power mode as well. The FTDI USB/SCI converter is externally supplied by the USB bus. The calculators MCU and display are powered through a boost converter with the start-up voltage of 0.65V, so it does drain its batteries pretty empty, before it stops working.

While the current S12G240 MCU is small, cheap, and power efficient, the S12XE100 would add some nice features to the calculator:

- 100MHz CPU with extended instruction set
- 32Kb of RAM
- EEPROM emulation which works like a non-volatile RAM
- second CPU (XGATE) to handle all I/O
- external bus interface to add even more RAM