The command line switches (fill in your own path names) should look like this:Īvrdude -C -v -p -c -P -b -Uflash:w: :i -U lfuse:w:0xFD:m -U hfuse:w:0xD1:m -U efuse:w:0xFE:m The avrdude burner must be used with the fuses set to 0xFD for the low byte, 0xD1 for the high byte and 0xFE for the extended byte. The controller is programmed via an arduino loaded with the ISP sketch using the SPI port or a dedicated AVR programmer. The floating point library used is a combination of both BigNumber.h (Nick Gammon) and math.h (avr-libc) and for printing out the results both scientific notation and standard format are supported. User operation is both key-driven and command-initiated. The 10bit readings are, largely, independent of the power supply and thus operation is fairly reliable over its range. The keypad is sampled consecutively from channel A0 (leftmost column to pin D14) to A3 (rightmost column to pin D17) and compared to a matrix of analog readings.

While the characters/bits are written to ledmap interrupts are disabled. The fonts array in flash holds the ASCII bitmap in (LSB to MSB from left to right). The internal ‘dutycycle’ determines the brightness of the leds which the user specifies as a percentage. The handler for timer1 switches on and off each successive column/digit depending on the bit pattern written into the internal ledmap array. The led display is treated like an 8x8 led matrix. The external arduino librariy used is he BigNumber (arbitrary precision) by Nick Gammon. In power down mode the current drops to less than 1uA. Using a CR2032 cell (220mAh for light loads and 150mAh for heavy loads) the unit should function for about 30 hours continuously with all segments lit. Of course, you can always choose to turn off the battery switch.Ĭurrent consumption, for hw version 2 with BOD off, at Vcc=2.5 varies from about 2mA to 5.5mA for a 50% display duty cycle as the number of lit digits varies from 0 to 8. In power down mode the current drops to less than 30uA. The voltage available to the circuit, common rail Vcc, varies from 2 to 3 volts while the controller will function down to 1.8 volts with a very dim light for red leds.Ĭurrent consumption, for hw version 1, at Vcc=3 varies from 6mA to 10mA for a 25% display duty cycle as the number of lit digits varies from 0 to 8. If the batteries are installed then they must be rechargeable for concurrent use with USB power. The power supply can be either external from a USB female type-B connector or internal from 2 AAA batteries. The preferred color should be red for low voltage operation - 2 volts minimum. The display consists of two SMA420364 which are 4-digit 7- segment common cathode led devices. The calculator is based on an atmega328P (at 4MHz) and uses all available pins,16 for the 8-digit led display and 4 analog pins one for each of the four columns of the 4x4 keypad. Transfer Function computation in s and z domains. There are a total of 8 key maps including programmer's mode. led displays powered by either a coin cell or 2 AAA rechargeable via USB batteries. Transfer Function computation in s/z domain.īased on an atmega328P, a 4x4 keypad and 8 7-seg.

Standard and scientific notation up to 14 digits. Stack based functionality with X,Y, Z & T registers.

Scientific calculator based on an atmega328P.Ī mixture of both BigNumber and avr-libc functions.

Rpn scientific