Archive for the “Usb” Category

Building a Bus Pirate

The dangerous prototypes Bus Pirate is a really cool probing device. A friend of mine also wanted to build one and that made ordering a few pcb’s an interesting option. Off course we went to dirty pcb’s as the boards are fully functional but not always perfect. That’s good enough for the low price they charge.

Now we wanted the Bus Pirate to fit on a 5cm * 5cm board but the layout is slightly larger then that. Well, my mate take the challenge to shrink the board and succeeded to do so. The silkscreen took a hit, but all components were squeezed into 5cm. It’s not perfect, for example the location of a decoupling cap should be closer to the pic. We received 14 boards and they all were just fine for what we wanted. The silkscreen is running a bit of the board, but that was our own doing. Something has to give when squeezing a design into max 5cm. ๐Ÿ˜‰

buspirate plus 2 levelshifters in one 5*5cm pcb

buspirate plus 2 levelshifters in one 5*5cm pcb

After separating the boards

Split pcb, one buspirate and 2 levelshifter boards

Split pcb, one buspirate and 2 levelshifter boards

Some parts we had available, most had to be ordered. Halfway through soldering components it looked like

Halfway soldered buspirate

Halfway soldered buspirate

The finished, flashed and now tested buspirate.

Buspirate, ready and tested

Buspirate, ready and tested

 

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The Microchip MCP2210 chip is an easy way to go from USB to SPI with one, dedicated, chip. Microchip also features an evaluation kit and breakout module for the MCP2210.

No need to program the chip. Everything you need is already on there.

Considering that this is very likely a pre-programmed dedicated chip I expect to find a 18F14K50 underneath just like the MCP2200 USB to UART conversion chip, see here and here. With the upcoming PCB design where an ISP header will be added this will be easy to verify with a PicKit.

 

In case you want to make your own breakout board and play with the chip please read on.

The schematic is from the Microchip evaluation board. I removed the 3.3V power and ISP header to boil down to the bare minimum board. The schemati now looks like this, note that the chip says MCP2200 in my schematic since there was no Eagle MCP2210 equivalent available. Luckily both are pin compatible so even though it says MCP2200 it will work jut fine for the MCP2210.

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