About this project
Really, Really Useful Breakout Boards
At SwitchDoc Labs, we build a lot of cool projects. Sometimes they become products, other times they are customer funded or proof-of-concept projects. MouseAir (named one of the 15 most creative Raspberry Pi Projects by Brit+CO), Project Curacao, SunTracker, SunAirPlus and the new Solar Powered Semi-autonomous robot SunRover are all part of the project flow around here. We often write articles about these projects that lands us on magazine covers. This Kickstarter is to take to production two boards that we find really, really useful. Check out our other products and useful blogs at www.switchdoc.com.Board 1: I2C 8 GPIO Extender - Adds 8 GPIO pins to your device through an inexpensive I2C Breakout Board
- I2C controlled
- 8 GPIO pins
- All pins can interrupt the computer
- Two bank power supply allows two banks of 4 GPIO pins to have 5V or 3.3V
- Can program GPIO pins to make up to 3 pin logic gates (PLD)
- Software drivers for Arduino and Raspberry Pi Included!
Board 2: Quad Power Management I2C Board - Switch on and off batteries, power supplies and solar panels
- I2C controlled
- 4 Independent Solid State Relays each with LEDs
- Each is able to switch 20V and 2.3A
- 4 Additional GPIOs
- Software drivers for Arduino and Raspberry Pi Included!
Full descriptions of these boards are below.
Current Status of Boards
The I2C 8 GPIO Extender board is fully tested will be released to production within the next two weeks. The Quad Power Management Board has just arrived in prototypes and we will start testing all the features. So far, the QPM Board is looking good. The LEDs work and the switches work!
More of Our Story
In December 2014, we successfully did our first Kickstarter, SunAir! Funded in 16 days. In April 2015, we successfully did our second Kickstarter, Three Really Useful Breakout boards. Funded in 11 days. Now, we are doing a third kickstarter, this time to facilitate the production of two boards that we have found very useful in the design of several of our projects. Prototyping is an essential part of product design, whether the project is for production or just to prove that it can be done.
Check out the rewards. You get a great discount on the initial production run of boards and of other goodness from SwitchDoc Labs. And these are really, really useful boards. Do we know how to build cool things? Just look that our projects have made the cover of three issues of Raspberry Pi Geek Magazine:
The second magazine contained a board that we successfully completed through the previous Really Useful Breakout Boards Kickstarter!
Here is the full scoop for our two Really, Really Useful Boards:
I2C 8 GPIO Extender Board
This board is an inexpensive I2C GPIO Extender Board. It allows you to add 8 pins of GPIO, with interrupts allowed on all pins, to any Arduino or Raspberry Pi design. It works with 5V and 3.3V and in fact you can have 4 pins at 5.0V while having 4 pins at 3.3V at the same time. It is based upon the Semtech SX1502 and it has some really cool features. Here is the block diagram for the board:
What are some of the applications for this 8 GPIO Extender board? Anytime you need additional GPIO pins. This happens all the time with the Raspberry Pi and with some of the newer, smaller Arduino boards. Do you want more interrupts on your Arduino or Raspberry Pi? You can use this board to generate interrupts that can then be read by the Arduino or Raspberry Pi.
The other advantage is that you can set each bank of four GPIOs to a different power supply, anywhere from 1.2V to 5.5V. Very flexible in mixed voltage systems.
Of course, the board is both 3.3V and 5.0V tolerant meaning your I2C bus can be at either of those voltages.
Another more subtle advantage of this board is that you can create logic gates (PLD - Programmable Logic Device). Do you need a couple of logic gates in your design? You can build XOR, Inverters, AND, NAND, OR, NOR, etc., etc. using this chip. Your choice!
Quad Power Management Board
Applications of the QPM Board
The Quad Power Management board has many applications that come to mind. Any time you want to switch a battery out of the circuit, switch from one battery to another, turn power off to a device, stack and unstack batteries or turn power on or off to a device, this is your board.
The three applications below are from a new SwitchDoc Labs project, SunRover. SunRover is a semi-autonomous tracked robot that is being developed here in Washington state, but will eventually make it down to Curacao to join Project Curacao in the tropics. Have to keep those trips to the Caribbean as business expenses!
SunRover has three computers. The first is the motor controller (TRex I2C controller made by Dagu) and connected to a Dagu set of robot TRex tracks.
The other two computers are an Arduino Mega 2560 (the power management computer - also does weather sensing) and the brains of SunRover, a Raspberry Pi 2 Quad Core computer.
The electronics will be packaged in a BUD enclosure as below. Note the Circuit Board Condo that we designed and 3D printed. It allows us to have three levels of PC boards in the box.
The three example applications for the QPM board are:
- Battery Stacker
- Solar Panel Multiplexer
- Robot Compartment Heater
To get the ~12V we need to run SunRovers motors, we need to stack 3.7V LiPo rechargeable batteries. It takes 3 batteries to get up to about ~12V.
The problem is that all of our Solar Powered Charging system is designed to charge 3.7V LiPo batteries. Our solution? Use two QPM boards to switch the batteries from a series to parallel connection and then charge the batteries from SunAirPlus. The QPM board even has two inputs per device. One with a protective diode and one with our. Perfect for our application.
Solar Panel Multiplexer
SunRover has 6 3.5W/6V solar panels. These will be on a "wing" across the top of SunRover. Each of these six solar panels can be switched by a Quad Power Management board and be connected in different ways to provide more power to the subsystem (Motors, Arduino or Raspberry Pi) depending on what needs it at the time and the Sun.
We are using four QPM boards to accomplish this.
SunRover Motors subsystem - up to 6 solar panels
Raspberry Pi subsystem - up to 4 solar panels
Arduino Power Management subsystem - up to 2 solar panels
Robot Compartment Heater
Our third example application of the QPM board is a resistive compartment warmer. The winters are cold up here in the frozen north and LiPo batteries and electronics need to be kept warm to keep working. We are accomplishing this by using the QPM board to switch 10W/20 Ohm resistors, one in each compartment. We have temperature sensors in each compartment that will give us the feedback we need to moderate the heat sent to the resistors. How do we control the heat coming off of each resistor? We pulse the QPM switches to only power the resistor for the amount we need. If we want 3.6W, we turn the QPM switch on 1/2 of the time (7.2W/2). We can make it generate just enough heat to keep the compartment at the right temperature. Very cool. Or hot in this case.
Risks and challenges
The primary risk in these boards is that of schedule. It is important to note that SwitchDoc Labs is already committed to bringing these two products to market, so this kickstarter can be viewed as a low risk item.
You do get a great price break!
The Arduino software for the I2C 8 GPIO Extender board and the Quad Power Management board is already complete. The Raspberry Pi software will be next.
The I2C 8 GPIO Extender is fully tested and will be released to manufacturing shortly.
The Quad Power Management prototype boards are now in house and the testing has commenced. So far, so good.
SwitchDoc Labs has already successfully completed two kick starters (SunAir and Really Useful Breakout Boards) and have shipped all the rewards. Our second kickstarter shipped rewards ahead of schedule!Learn about accountability on Kickstarter
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