icestick_6502

A small 6502 system built on a Lattice Icestick FPGA development board

prerequisites

To build this you will need the following FPGA tools

• Icestorm - ice40 FPGA tools
• Yosys - Synthesis
• Nextpnr - Place and Route

Info on these can be found at http://www.clifford.at/icestorm/

You will also need the following 6502 tools:

• cc65 6502 C compiler (for default option) https://github.com/cc65/cc65

Building

git clone https://github.com/emeb/icestick_6502.git
cd icestick_6502
git submodule update --init
cd icestorm
make

Running

Make sure you've properly set up udev rules for the icestick, then plug it in. Start a terminal on the icestick's USB serial port - probably found at /dev/ttyUSB1 and configure it for 9600 baud. Then load the previously built bitstream

make prog

You should see a message printed to the terminal window and the icestick LEDs should start to flash in sequence.

CPU coding

By default the build system fills the ROM with code based on the C and assembly source in the cc65 directory. Optionally you can use pure assembly to create the ROM with the following commands

make assembly
make

within the icestorm directory.

Simulating

Simulation is supported and requires the following prerequisites:

• Icarus Verilog simulator http://iverilog.icarus.com/
• GTKWave waveform viewer http://gtkwave.sourceforge.net/

To simulate, use the following commands

cd icarus
make
make wave

This will build the simulation executable, run it and then view the output.

Thanks

Thanks to the developers of all the tools used for this, as well as the authors of the IP cores I snagged for the 6502 and UART. I've added those as submodules so you'll know where to get them and who to give credit to.