HardLabs

CR2021 CPU v2

derpflanz·castle-runner·ComputerDesigns/CR2021_CPU_v2/CR2021_CPU_v2.kicad_pcb

CR2021 CPU v2 PCB layout, top view — open source AVR/Arduino board by derpflanz

About the CR2021 CPU v2 PCB

CR2021 CPU v2 is an open source AVR/Arduino PCB design by derpflanz, published on GitHub. It is a 2-layer board measuring 178.4 × 115.6 mm, with 43 components from 35 distinct parts.

Its main chip is the ATmega328-P, from the AVR/Arduino family. Other key parts include the LM324, 74HCU04, 7400, 74LS163 and W65C22NxP. By type, the board carries 8 ICs, 3 capacitors, 3 resistors, 2 connectors, 1 crystal and 1 speaker.

From the project

This is my hobby project in making a 6502 based 8-bit computer from scratch. The end goal is to have it run Castle Runner, a game I made many moons ago.

This is my hobby project in making a 6502 based 8-bit computer from scratch. The end goal is to have it run Castle Runner, a game I made many moons ago.

Castle Runner is built from scratch, including the assembler (new version, written in C). I created my own assembly language dialect to assemble the machine language code. That ML can then be written to a EEPROM. For which I built my own EEPROM programmer.

Main components on the CR2021 CPU v2

LM32474HCU04740074LS163ATmega328-PW65C22NxP

CR2021 CPU v2 bill of materials (BOM)

43 components, 35 distinct parts.

QtyPartRefs
2
LM324
U1, U7
1
74HCU04
U2
2
7400
U3, U4
1
74LS163
U5
1
ATmega328-P
U6
1
W65C22NxP
U8
1
Crystal 8MHz
Y1
1
Conn_02x06_Odd_Even
J1
1
Atmega328 Programmer Interface
J3
4
74LS273
$4002, $4003, OUT1, OUT2
1
DATABUS_8BIT
BUS1
1
ADDRBUS_16BIT
BUS2
1
Display
CONN5
1
+5V
CONN6
1
ADDRSEL_IN
CONN7
1
ADDRSEL_OUT
CONN8
1
WD65C02S
CPU1
2
74LS540
IN1, IN2
2
74LS138
IN_DEMUX1, OUT_DEMUX1
1
Speaker
LS1
Show 15 more
QtyPartRefs
1
R/!W
PIN1
1
!IO_Active
PIN2
1
EXT_CLK
PIN_CLK1
1
32 kB RAM
RAM1
1
ROM ZIF Socket
ROM1
1
10k
RPOT1
1
10M
R_CLK1
1
22
R_CLK2
1
RESET
SW1
1
IO_Active
D1
2
22pF
C1, C2
1
100uF
C3
1
1k
R1
1
330
R2
1
3.3k
R3

CR2021 CPU v2 design files

The KiCad project lives in the derpflanz/castle-runner repository on GitHub; these links point at the commit this page was built from.

CR2021 CPU v2: common questions

What microcontroller does the CR2021 CPU v2 use?

The CR2021 CPU v2 is built around the ATmega328-P, from the AVR/Arduino family.

How big is the CR2021 CPU v2 PCB?

The CR2021 CPU v2 measures 178.4 × 115.6 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the CR2021 CPU v2?

43 components, from 35 distinct parts. The full bill of materials is listed on this page.

Where can I download the CR2021 CPU v2 design files?

From the derpflanz/castle-runner repository on GitHub, which has the KiCad layout and the schematic; the links under Design files point to each one.

Can I use the CR2021 CPU v2 design in my own project?

The repository has no license, so all rights stay with derpflanz. Use it as a reference, and ask the author before reusing the design.

Can I test firmware for the CR2021 CPU v2 without the hardware?

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

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