NP-41 Emulator (may be)

[Chris Chung]

(01-29-2016 08:15 PM)jch Wrote:  Chris, this will really be a 'Swiss Army Calc'. Looks like your PCB will be a masterpiece !
I don't know if the MCU has Timer or PWM capabilities, but you may use only one PWM pin for LCD backlight ?
And, though I still have some computers with real serial Com port, I wan't ask for MAX232 RS232C level translators ;-).

Jean-Christophe.

Jean, this is no masterpiece! I am a amateur on PCB design. Never learnt to use Eagle. The way I am using Fritzing is like manually placing and routing everything w/o a proper schematic. I am always investing in the bare minimal to get things done.

There are 3 16 bit timers. I will be using one for the piezo buzzer. I used 2 pins for the LEDs mainly to avoid adding transistors and there are may be 6 leds that could draw some current. And I don't want to manage too many peripherals / timers, is using current limiting resistors to manage them.

Again it is not worthwhile to put in an extra chip for USB serial when one can get a cable for a dollar on ebay. The G2955 does not have built-in USB.

I managed to compile in the Math 1C ROM introduced by Bob and it is working (I think), the math is too complicated for me, I just try the "FOUR" function and enter a brunch of numbers to let it roll. Nonpareil supports only ROMs w/ fixed page. I had to force the ROM to look like it is fixed at page 8 instead of variable page 8 to f.

Still have to finish the PCB and send for fabrication.