My robotics class is in a unique situation in that we are using the Wallaby from KIPR as a robotics controller with the original version 1 Create from iRobot. Almost everybody else has moved on to the Create 2 but I’m not a fan and we’ve still got a lot of Create 1s around so we’ll use them until they die. But this leaves us in an interesting position getting them to communicate. This isn’t a super exciting post but maybe it’ll help somebody.
We’re using the Wallaby from KIPR in my robotics class this semester. I’d been told at the beginning of the semester that the pull-up resistors on the Wallaby weren’t working so many of our old bump sensors would not work. So, I made this quick little adapter board to add pull-up resistors myself. The pins are female headers that are extra long so that they can be plugged in directly without any other pins (I found them by searching for stacking headers). I decided to only do four pins so that the other slots could be left open for other sensors that might not want a pull-up resistor. If I did this again, I’d do only three or six slots since stacking headers are easy to find in those lengths; I used 10 pin headers cut in half and sanded flat. So there you go. Not too interesting but documented for anybody else who may want it.
Here’s my schematic and board design for a simple low side switch using a N channel mosfet. It’s a simple circuit that has a input for positive and negative and an output for positive and negative connections. Pretty self explanatory. It seems like every time I go to work with mosfets I have to spend a good 5-10 minutes reminding myself how they work. So here’s a reminder to myself for the next time I go looking and maybe it’ll help somebody else out.
Here’s my schematic and board design for a simple high side switch using a P channel mosfet. It’s a simple circuit that has a input for positive and negative and an output for positive and negative connections. Pretty self explanatory. It seems like every time I go to work with mosfets I have to spend a good 5-10 minutes reminding myself how they work. So here’s a reminder to myself for the next time I go looking.
I’m working on a robot project and one of the intended uses is to teach line following to college students. For this, I’m making an array of 9 RPR-220 reflectance sensors. This post will describe the part I’ve designed and the reasoning behind it. It’s a bit rambly so consider yourself forewarned.
Several months ago I wrote a post about a breakout board for the TB6612 motor driver. You can find that here. The reason I made my own breakout board for this was that the ones available from Sparkfun, Adafruit, and Digikey didn’t have diodes on the board. The TB6612 says it has internal diodes but those are small and I saw somebody online suggest always using external diodes. Today I realized I wasn’t sure if I actually needed them or not so I decided to do my own test to find out.
The little board was built to charge a single lipo battery using the MCP73831 from Microchip. I plan to use it along with several other boards featured on this blog in a larger project, but I like to break things up and make sure they’re working individually before making them work together. Continue reading “Simple LiPo Battery Charger with the MCP73831”