FPGA 8-Bit TV80 SoC for Lattice iCE40 with complete open-source toolchain flow using yosys and SDCC
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iceZ0mb1e aims to build a TV80 based demonstration system-on-chip using complete open source FPGA toolchain flow (http://www.clifford.at/yosys/) including firmware compilation with SDCC.

This is a completely free microcontroller based on customizable open source components.

iceZ0mb1e consists of following parts

  • TV80 CPU (https://opencores.org/project,tv80,overview)
  • SoC RTL design, iceZ0mb1e consists of:
    • RAM and ROM (using BRAM or SPRAM)
    • UART 16450 compatible
    • Parallel IO
    • i2C Master
    • SPI Master (all CPOL/CPHA modes supported)
  • Top-Level designs for some iCE40 development boards (upduino, HX8K Breakout Board)
  • C based firmware, that is embedded into BRAM blocks during build
  • API Functions for all hardware interfaces
  • Complete make based flow, to be as clean as possible

Supported FPGAs

  • Lattice iCE40 HX8K
  • Lattice iCE40 UltraPlus 5K

No special blocks are used, so every comparable FPGA in size would fit.

Test Firmware

The included test firmware will check the RAM size and write some data to IO ports (blink LEDs). Simple UART access with 9600-8N1 is provided.

Address Map

  • ROM = 0x0000 - 0x1FFF (8192 Byte)
  • RAM = 0x8000 - 0x9FFF (8192 Byte)
  • 16450 UART Base IO = 0x18
  • Parallel Base IO = 0x40
  • i2C Master = 0x50
  • SPI Master = 060

Build for Target

  • UltraPlus 5K (default target): make firmware && make fpga && make flash
  • HX8K: make firmware TARGET=8k && make fpga TARGET=8k && make flash TARGET=8k


  • make sim TARGET=8k

Running SoC

Installing yosys toolchain

Installation of essentials for building and running yosys, icestorm and arachne-pnr toolchain (Ubuntu 16.04):

sudo apt-get install build-essential clang bison flex \
                     libreadline-dev gawk tcl-dev libffi-dev \
                     pkg-config python cmake libftdi-dev

Get yosys, icestorm and arachne-pnr (latest version supports Lattice UltraPlus) and compile toolchain:

git clone https://github.com/cliffordwolf/icestorm.git
cd ./icestorm/
make clean
make -j$(nproc)
sudo make install
git clone https://github.com/cseed/arachne-pnr.git
cd ./arachne-pnr/
make clean
make -j$(nproc)
sudo make install
git clone https://github.com/cliffordwolf/yosys.git
cd ./yosys/
make clean
make -j$(nproc)
sudo make install

Installing verilog simulator

sudo apt-get install iverilog gtkwave

Installing SDCC toolchain

sudo apt-get install sdcc sdcc-doc sdcc-libraries sdcc-ucsim \
                     z80asm z80dasm srecord

Why iceZ0mb1e?