So far it's looking like all the conditions I need to meet to get the voltage checker implemented are coming along nicely. I have the board being fabricated and already have all of the parts in hand. I breadboarded the circuits and they are all functioning nicely and the driver is coming along pretty well.

One thing I'm looking at exploring in the near future is FPGAs because with the price coming down, I feel they are going to start becoming more popular soon. I used to just love designing logic using gates when I was a teenager and in fact created a programmable robotic arm based on an EEPRO...

Tonight I hooked up the shift register to an LED bar graph and wrote a little demo program and some utility functions in C to animate the LEDs. It turns out WiringPi has a library for the 74HC595 which makes things very easy. After getting this functioning, I don't think there will be any problems with the board design, so I feel pretty good about it. I also wrote some initialization code for the columns. Oh, the only other thing I was considering is writing it in Python, and at this point the only reason I would do that is if I can interact with the Linux UI and display an icon much more easi...

I'm so awful. I revised the design again, so I cancelled my order, uploaded the new design, chose the Super Swift service which takes up to 5 days instead of 12, but doubles the cost. and resubmitted it Also, I went with free shipping because I found they were actually pretty close to where I live and the shipping time would be very fast anyways. It has already gone into production now, so there won't be any more changes, but I'm actually pretty happy with how it ended up. If there turns out to be a major design flaw, at least I know it will only cost me $7.30 and a week of waiting.

On a diffe...

I went ahead and designed a board that is only 1 inch by 3/4 of an inch which I'm pretty sure will be able to fit. By making it so small, I was able to get the cost down to $3.65 for 3 boards and I had the option of free shipping. I opted for priority mail shipping to speed it up by up to 3 days. If anybody is interested in the design, it's available here.

I thought that when I connected the battery backwards to the PowerBoost 1000, I had ruined it so I ordered a new one. It turns out I just didn't wait long enough. Oh well, that can either go towards a different project or a second calculator...

Yesterday I didn't get a whole lot done. I mostly worked on some of the driver code and changing it from reading 4 inputs to more of a matrix.

Today I hooked up the MCP3008 and enabled the auxiliary SPI and it's working great. I found some software called GBZBatteryMonitor which is really just a stripped down version of PiCheckVoltage that's a little newer. I updated the MCP3008.py file with the correct pins and it worked well. It turns out when I swapped connectors for the battery, the new connector had the wires opposite of the one that came with the battery. So swapping connectors as well a...

I ran into another issue with trying to get the MCP3008 chip working. It uses SPI and apparently the Raspberry Pi only has to Chip Selects available for its use on the main SPI. Both of these are in use by the display and touchscreen which are higher priority than a battery level check. Now there is an auxiliary SPI as well, but that would end up taking 4 pins as opposed to the one or two pins I was planning on using because I have to use a different set of MISO, MOSI, and Clock pins as well. In order to do that, this means I will need 4 things to be in place:

1. PiCheckVoltage will need to run ...

Ok, so I ended up getting the new calculator in the mail as well as some as the Raspberry Pi 3 B+ yesterday. However, I had a delayed package as well as a couple that were delivered to the apartment office right before it closed, so I had to wait until they opened today to pick them up. So now I also have a circuit board holder, a replacement magnifying glass (like the one I used to examine the circuit board traces), the MCP3008, and a raspberry pi cobbler. I ended up giving my Raspberry Pi 2 to my son because he was excited to get his hands on a Raspberry Pi. Also, I wasn't sure if I would ne...

Today I got Bluetooth audio working. I just followed this guide and aside from a misspelling or two, it went pretty smoothly. I wasn't able to get it to play over command line using SSH, but it did play after I installed VLC and double-clicked the MP3 file, which is good enough for me.

A while back, I had discovered that you could download Lynda.com videos with youtube-dl, which placed stuff unsorted. I created an AppleScript script that would go the the Lynda website, get the list of files in the course and sort and rename all of the files accordingly. Over time, I got it working 100% perfect...

Don't you just love breakthroughs? I was looking at the Network mapping data I had and swapped some columns and realized that it is in fact a grid of 7x8 (at least electrically) plus the on button. It's just not arranged physically in the same grid that it is electrically, but it still the same. That means I have the option of using the GPIO-Matrix Device Tree Overlay like I originally wanted.

I received the second USB port and have decided to go with the Adafruit one. The contacts are better and I think the shape works better, but in all honesty, I think either would have worked out just fine...

I found a great page here about how to write something in C that would be a great base point. If I run it in the background as a service or a daemon just like FBCP, then I think that will work fine. I'm also thinking about reading in a config file or something so that I can make the keyboard function different depending on the mode. I went ahead and set up SSH and got it to compile an example so that I can modify it from there.

I'm kind of getting anxious to put everything in the calculator case soon as I feel the hardware part of this project is coming to a finale and then it will just be sof...