The CX80 – A Brief Description
The CX80 is a computer based on Z80 CPU that you can build at house with a really low price. Of course I asked for some more in-depth knowledge of electronics such as knowing how to make a single sided pcb and know how program the atmel microcontroller. If you are not able to make it alone, do not worry, I can build it for you! I do not provide: a regulated 4.5 – 5.0 Volt DC mains adapter with a 1.3mm jack (centre positive) capable of supplying about 800 mA (or more), a sd card (FAT16/32 formatted) and an RCA cable to connect the CX80 at the television, a piezo speaker and a switch for the reset pins.
On CX80 board there are four jumpers that are used to configure the system or optional connections:
- JP1 – Reset (if you short this pins, CX80 reset)
- JP2 – PAL/NTSC Video (closed = NTSC, open PAL output)
- JP3 – Rvideo (if shorted, enabled the 75 ohm resistor on video signal. Short it if you see grey color on video)
- JP4 – Piezo sound (connect a piezo speaker for sound, pin2 = GND)
The SDBoard for CX80
The CX80 required the SDBoard to properly access the SD card. In project zip file you can find the schematic necessary to its construction. IMPORTANT! The signals of the data bus of the CX80 are at 5 volt, the SDBoard is necessary to reduce the voltage to 3.3 volts, for a correct operation of the SD card
The pinout of SD card port on CX80 is:
- PIN1 = SD_SEL
- PIN2 = DI
- PIN3 = GND
- PIN4 = 3.3 Vcc (from voltage regulator on CX80 board)
- PIN5 = SCLK
- PIN6 = GND
- PIN7 = DO
I also added a pdf file that explains how to create an sd card breadboard socket. The file is “Cheap-DIY-SD-card-breadboard-socket.pdf” (from Instructables site) and is located in the folder “Schematics\SDBoard for CX80”.
Be very careful to observe the orientation of the pin, otherwise it will not work at all.
The female header SV2 must be connected to CX80 SDCard port.
The female header SV1 must be connected to SD card breadboard socket.
When you mount the SDBoard on the CX80 you need to turn it upside down, so as to see the bottom part of the electrical circuit.
For more information see file CX80_Manual.pdf into zip project file.
Click here to download the entire project
The author is not responsible for any malfunction or damage to property or people resulting from the use of the information contained in this document.
The CX80 is designed to be easily made at home, but of course its assembly requires some knowledge of electronics, but if you are not able to build it alone, I can build it for you. If interested please email me at the address below – once I get enough enquires it becomes economical to source the parts for another batch. The price for a complete board is € 23 (plus postage + 3.9% Paypal fee) – I can send them worldwide. Please bear in mind I make these as a hobby and don’t have the resources to buy in bulk so the price pretty much reflects the total cost of the components. I solder everything by hand and make very little (if any) profit.
The CX80 is now also available in kit form! Here’s what you can choose from:
- The CX80 pre-assembled with SD board is 26€ + 1.47€ for PayPal.
- The CX80 in full kit is (with SD board PCB) 20€ + 1.47€ for PayPal.
- The CX80 small kit (preprogrammed ATMega32 + preprogrammed ATMega8 + PCB + SD board PCB) is 14€ + 1.47€ for PayPal.
- The CX80 micro kit (preprogrammed ATMega32 + preprogrammed ATMega8) is 8€ + 1.47€ for PayPal.
Shipping in Europe is 12€ because the package weighs is less than a kilogram.
ecalogiuri at gmail (point) com
CX80 upgrade to 1.4 version (01/08/2013).