eonduino

EON cpu system with arduino and real hardware. An emulator is included. This is a very simple 32 bit EON cpu system, with 8KB ROM and 128KB RAM. The estimated clock frecuency is about 1MHz.

hardware parts

• avr Mega (5v) (almost any avr board will work) or esp8266 nodemcuv2 (recommended, 3.3v)
• 24LC256 serial EEPROM, 128Kbit, I2C, 3.3 or 5v
• 23LC1024 serial RAM, 1Mbit, SPI, 3.3 or 5v
• DS1307 serial RTC, I2C, 3.3 or 5v
• breadboard, resistors, leds, one button switch and dupont wires

build

Prerequisites:

• eonrom.img version 0.1.0 from eonrom
• arduino-cli
• a serial terminal emulator. I use picocom, but any other will work.

to build emulator, just type make
to build arduino image, type make compile
and finally type make upload && make com to enjoy your system !

diagram

check the gallery images. From top to bottom:

• EEPROM
• I2C bus
• RTC clock
• space for SPI card reader (not included in this model, it's only 3.3v)
• SPI bus
• SRAM
• leds: red = error, blue = reset, green = run
• reset button

gallery

avr mega pinout

• reset button: pin13(active low)
• leds: pin10(RUN) pin11(RESET) pin12(ERROR)
• i2c bus: pin20(SDA) pin21(SCL)
• spi bus: pin52(SCK) pin50(MISO) pin 51(MOSI) ping 53(SS active low)

esp8266 mega pinout

• reset button: D0(active low)
• leds: LED_BUILTIN(RUN)
• i2c bus: D2(SDA) D1(SCL)
• spi bus: D5(SCK) D6(MISO) pin D7(MOSI) D16(SS active low)

eeprom pinout

                  ++++++++
             SDA -|      |- GND
             SCL -|      |- A2 unconnected
  unconnected WP -|      |- A1 unconnected 
             VCC -|  \/  |- A0 unconnected
                  ++++++++

i2c bus

i2c bus needs 2K pullup resitors, at least in SDA(blue). SCL(orange) resistor can be omitted

rtc pinout

    unconnected -+
    unconnected -+
            SCL -+
            SDA -+
            VCC -+
            GND -+

spi bus

• SCK: orange
• MISO: white
• MOSI: blue

sram pinout

                ++++++++
          MOSI -|      |- GND
           SCK -|      |- 10K - VCC
     VCC - 10K -|      |- MISO
           VCC -|  \/  |- SS - 10K - VCC (active low)
                ++++++++