This Hello World project demonstrates using the ZPUFlex processor in its simplest form.

In the Makefile we specify the regular ctr0.s (as opposed to the small variant) which includes instruction emulation code for the optional instructions. We need this since we use the ZPU in its most compact form, which omits many optional instructions. Since we’re using emulation we don’t ask the compiler to avoid any instructions. We specify the standalone_simple.ld linkscript, which is suitable when the ROM code will appear in low memory.

The Makefile builds an elf binary, converts that to raw binary format, then uses the “zpuromgen” command and some sed trickery to create a VHDL ROM file that can be included directly in your Quartus project. In the RTL we provide a simple UART (transmitter portion only), and instantiate the ZPUFlex core with all the optional features disabled. The entire project, including UART, is just 684 logic elements on the DE1.

Quartus projects are provided for the DE1 and MIST boards to date – others may well follow.