Imported from GitHub: dlutz52/Homebrew-CPU-PCB · commit b8eb86a · license GPL-3.0

Description

This repository contains a complete KiCad project for creating a PCB that implements the circuit design of Ian Ward in his YouTube video with the title of Homebrew CPU Project

README

Homebrew CPU Project PCB

My inspiration for this PCB came from following Ian Ward's project on his web site:

20xt6 Homebrew CPU Project

This PCB implements the LCD Character Display: Milestone 1 Complete! stage of this series of videos.

But there is more to come in the future, so checkout Ian's videos on his future plans:

Discrete Logic Rhythm Game Prototype (no CPU)

Designing a Rhythm Game: Homebrew CPU Plan Step 2

Maze Game Prototype (no CPU!)

I will try to keep up with him.

PCB Front Image

PCB Back Image

Homebrew CPU PCB BOM

Wed, Mar 21, 2024, 08:58:15

Component Count: 25

Ref	Qty	Value	Vendor\Part #	Description
C1, C3, C5	3	10uF	Generic	Electrolytic capacitor
C2, C4, C6	2	.01uF	Digikey\FG28C0G1H103JNT06	Unpolarized capacitor
D1	1	YELLOW\Reset	Generic	LED\3mm\Yellow
D2	1	RED\HALT	Generic	LED\3mm\Red
D3	1	BLUE\CLOCK	Generic	LED\3mm\Blue
D4, D5	2	10_SEG_LED BAR_GRAPH (Blue)	Digikey\1497-1079-5-ND	LED Bar Graph\Blue\1x10
D6	1	10_SEG_LED BAR_GRAPH (Yellow)	Digikey\754-1179-5-ND	LED Bar Graph\Yellow\1x10
D7	1	GREEN	Generic	LED\3mm\Green
J1	1	PinSocket_1x16_P2.54mm_Vertical	Generic	Female Pin Header\1x16\2.54mm pitch
J2	1	UJC-HP-M-G-5-MSMT-TR	Digikey\2223-UJC-HP-M-G-5-MSMT-TRDKR-ND	Type C/20 VDC/3A/Horizontal/6 Pin/Power Only
R1, R3, R8	3	1Kohm	Digikey\13-MFR-25FTE52-1KCT-ND	Resistor\1Kohm\1%\1/4W\Axial
R2, R6, R7, R9	4	330ohm	Digikey\13-MFR-25FRF52-330RCT-ND	Resistor\330ohm\1%\1/4W\Axial
R4	1	220ohm	Generic	Resistor\220ohm\1%\1/4W\Axial
R5	1	3ohm	Generic	Resistor\3ohm\1%\1/4W\Axial
R10, R11	2	5.1Kohm	Digikey\13-MFR-25FTE52-5K1CT-ND	Resistor\5K1ohm\1%\1/4W\Axial
RN1, RN2, RN3	3	470ohm	Digikey\4609X-101-471LF-ND	Resistor Array\8 Resistors\470ohm\9SIP
RV1	1	10Kohm	Jameco\2276439	Panasonic EWAQ30C15A14 Audio Slide Pot
RV2, RV3	2	5Kohm	Digikey\3386P-1-502LF	Trimmer Pot\5Kohms\0.5W\1/2W\Through Hole
SW1	1	TL2230	Digikey\EG6031-ND	Switch\Pushbutton\DPDT\Through Hole
S1	1	REG SELECT	Digikey\450-1654-ND	Switch\Tactile\SPST-NO\0.05A\24V\Through Hole
S2	1	ENABLE	Digikey\450-1654-ND	Switch\Tactile\SPST-NO\0.05A\24V\Through Hole
U1, U3	2	LM555	Digikey\LM555CNNS/NOPB-ND	555 Timer/Oscillator\100kHz\8-PDIP
U2	1	74LS00	Digikey\296-1626-ND	NAND Gate IC 4 Channel 14-PDIP
U4, U5, U6, U7, U8	5	74LS163	Digikey\296-3661-5-ND	Binary Counter\4 Bit\Positive Edge\16-PDIP
U9, U10	2	SST39SF040-70-4C-PHE	Digikey\SST39SF040-70-4C-PHE-ND	FLASH Memory\4Mbit\70ns\32-PDIP

The LCD and its 16-pin male header are represented only with 3D models, but you need a 2004 LCD with a soldered 16-pin male header with a pitch of 2.54mm to plug into the 16 pin female header to complete this PCB. I have found the best place to get these is on eBay.

Do NOT try to use a 2004 LCD with an I2C adapter on it.

Most symbols/footprints/models are contained under the 'libraries' directory. Capacitors, resistors and LEDs use KiCad symbols/footprints/models.

KiCad 7.0.10 was used to create this PCB. KiCad 8.0.1 is out now and this project opens in that version. The newer KiCad will warn that this project was created in previous version and will be saved in a the newer format. When closing the schematic or a PCB just discard any changes. If you do not you will not be able to use KiCad 7 any more without difficulties.

Models in KiCad's 3D view will display an appropriate socket under the ICs but these can be omitted on the PCB - they are used to make it easier to replace any components should they need it in the future. The only exceptions are the sockets for the SST39SF040 FLASH chips. These chips can be changed out for different program\lookup combinations, so you do not want to solder them to the PCB. I would recommend using 32-pin sockets from Aries Electronics or something equivalent, for example, Digikey\A410AE-ND.