Description
This is the mainboard for my modular computer based on the RC2014 Design. Scroll down to the end of this page to download the PCB and the Bill of materials.
- It has a 12v Input Socket and converts this to 5V and 3.3V. (3.3V can be disconnected from the module boards if you don’t use it).
- It supports Not Reset signal, Button and Led indicator. Also inversion to Reset Signal.
- You can use a full size or half size Crystal Oscillator, Connect this through a Jumper to a 74LS393 to get 1/2, 1/4 , 1/8 , 1/16 etc of the crystal frequency. Pass the main frequency or the derivatives to the mainboard to drive the rest of the boards.
Notes
- You must connect J_CLKSELECT with CLK CON or CLK_out_16. If not you can use a board to provide the clock signal.
- If you want to have 3.3V support for your module cards you must connect JP20 with Pin 36, there are two vias to help you do so, just solder a cable between those two.
- If you want to use a Crystal oscillator on the motherboard you must put a jumper on JP_CLK16
- The transistor BC546 can be replaced with other similar NPNs like BC547
- You can use J18 to connect a Reset button to a box with a cable
- J10 and J19 Terminal Blocks are used if you want to connect the board with a 5v – 3.3v regulator and not use the 12V socket or J9 TBlock.
- Important Use FR4 Board. I used FR2 and everytime i put a module board i have to provide support underneath otherwise it bends a lot.
- You will need a big PCB (26×20 cm), almost a full A4 size, a 30x20cm is available.
All connectors are Female Connectors SIL except the ones that are used as jumpers JPxx that are Male.
Schematics
PCB
The Bill of materials – all the components you need