A few months ago, Kornel, one of our customers, told us that he wanted something similiar to PiFace. Inspired by this product, I thought that I could make something else which utilizes the shields and sensors designed for Arduino. There are thousands of different kinds of shields and sensors for Arduino already existing in the market. They are mature in hardware and most of them are provided with open source code.
I told my idea to Kornel and he said the stuff I was going to design is already in the market. However, I decide to design something has more features compared to Cooking Hacks’ Raspberry Pi to Arduino Bridge. I named the product RasPiDeck because it was designed to load exteral shields or sensors. Here is some features which I think might be useful or nessessary for RasPiDeck.
- It should handle 5V input without any off-board component
- It could drive shields/sensors which only accept 5V logic
- It must have its own 5V-3.3V LDO, since the LDO on Raspberry Pi is already heavily loaded.
- The SPI/I2C interface of RasPiDeck should be able to work on both 3.3V and 5V device.
After a month working(schematics, layout, component sourcing and PCB manufacturing), the first version of RasPiDeck looks like this
It has 19 jumpers on board which are used to select the direction of the header pins, the logic level of I2C and SPI interface and the source of the referece voltage for onboard ADC. After my colleague Peng saw this, he said “If I were a newbie, I will be overwhelmed by the jumpers, and it is quite inconvenient to manually config 19 jumpers” I decided to take his advise and make revision to the first editon. I was involved in another project which has higher priority after a few days working on the second revision, so after two months the second revision comes true
I replace all the jumpers with SPDT analog switches and add a I2C IO expander to control the switches. Now, it looks less overwhelming and user could use code to config the IO directions/voltage levels and the logic level of I2C and SPI interface.
Below is what it looks like when it sits on a Raspberry Pi,
This product will be handed over to factory next week and it will be ready in about three weeks. As all of our products, the board color will be blue and the pad will be gold plated. The datasheet will be ready before the product is ready to market and all the technical details will be there.