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Cpu

MichaelBell·RV4028·cpu/cpu.kicad_pcb

Cpu PCB layout, top view — open source FPGA board by MichaelBell
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About the Cpu PCB

Cpu is an open source FPGA PCB design by MichaelBell, published on GitHub under the BSD-3-Clause license. It is a 4-layer board measuring 84 × 40 mm, with 38 components from 12 distinct parts.

Its main chip is the ICE40HX1K-VQ100_RV4028, from the FPGA family. Other key parts include the W25Q80DVSS and AP2112K-1.2. By type, the board carries 19 capacitors, 11 resistors, 3 ICs, 3 diodes and 2 connectors.

From the project

RV4028 - A hackable Risc-V computer

RV4028 is intended to be a modular Risc-V computer, similar to the excellent RC2014 Z80 homebrew computer.

The idea is to create a minimal Risc-V system that is easy to understand and extend.

The inspiration for this came from @theJPster's post.

All hardware and software are open source and permissively licensed.

The system bus has a 32-bit address and 16-bit data, which fits reasonably well with an RV32 system and readily available (P)SRAM chips, and runs at 3.3V.

Cpu, from the project README
From the project README

Main components on the Cpu

ICE40HX1K-VQ100_RV4028W25Q80DVSSAP2112K-1.2

Cpu bill of materials (BOM)

38 components, 12 distinct parts.

QtyPartRefs
1
ICE40HX1K-VQ100_RV4028
U1
1
W25Q80DVSS
U2
1
AP2112K-1.2
U3
1
~
J1
1
Conn_01x08
J2
1
1N4148W
D1
2
LED
D2, D3
3
1uF
C1, C3, C4
3
4.7uF
C2, C5, C6
13
100nF
C7, C8, C9, C10, C11, C12, C13, C14 +5
9
10k
R1, R2, R4, R5, R6, R8, R9, R10 +1
2
2.2k
R3, R7

Cpu design files

The KiCad project lives in the MichaelBell/RV4028 repository on GitHub; these links point at the commit this page was built from.

Cpu: common questions

What microcontroller does the Cpu use?

The Cpu is built around the ICE40HX1K-VQ100_RV4028, from the FPGA family.

How big is the Cpu PCB?

The Cpu measures 84 × 40 mm, has 4 copper layers and is 1.6 mm thick.

How many components are on the Cpu?

38 components, from 12 distinct parts. The full bill of materials is listed on this page.

Where can I download the Cpu design files?

From the MichaelBell/RV4028 repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.

Can I use the Cpu design in my own project?

Yes, under the terms of its BSD-3-Clause license, which MichaelBell chose for the repository.

Can I test firmware for the Cpu without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug FPGA firmware against it before you order a PCB.

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