The goal - provide a wizard above the stove to do cool things 
i.e. a Smart Range Hood that can run itself and let my wife summon me for dinner. See blog post #1 for links to everything.
Many things have been happening...
I've been super busy with this project ever since Pi Day / PCB Day when my boards arrived. I've done lots of soldering, chasing around, and troubleshooting, designing boxes, and 3D printing. I'll try to keep this blog post short, but include some video links with lots of of demonstration of where things are at. I'd like to send out a HUGE thanks to my wife for letting me sprint to the finish line on this.
PCB Assembly
I got the two boards that I ordered back in Post #9. I found that I had missed one trace and had to route it manually. I soldered a bunch of 0805 surface mount components like resistors and caps which I've never done before. The final PCBs look much more presentable than the breadboard nonsense I had going on before. Other things I would do differently next time - Label ALL pin headers in silkscreen. I ended up doing a fair amount of troubleshooting with the first "prototype" system ever built of this and know what all the pin headers are supposed to do would have been very useful. Also, I found one minor mechanical interference that should have been caught beforehand. The ADC board touches the header for the DHT22; but there is enough slop that I can wedge them both in and make it work.
Since I ordered multiple boards ganged on a single wafer, I had to cut them apart. I drilled a bunch of holes to perforate them, then snapped it. That was followed up with lots of filing to smooth it out. I think that I could have gotten V-Cut scoring to make this a lot easier, and will have to look more into that next time around.
The main board also had a feature I added - a pass-through for the ribbon cable of the Pi Cam. I drilled out a slot in the board so the Pi Camera's cable comes out right next to the Grid Eye's cable and they run together out to the box. These boards were only 2-layer, so the ground plane was the only thing that was cut through. I could have also masked off the ground plane in this area as an option.
Drilling out a slot for the Pi Camera ribbon cable to pass through right by the GridEye connector.
Headers / Jumper wires
I found and picked up a bunch of kits leading up to this project. They included JST pin connectors and regular .1" pin headers; plus a "sample book" of 0805 surface mount resistors and caps. These really enabled the rest of the project to be done in a very clean and professional looking manner. One problem that I am still fighting is that the crimping tool I got combined with my lack of skill caused a lot of headache in trying to do things correctly. I kept crimping the pins on the jacket or over-crimping them the connector would fall off.
DHT Board after assembly
Main PCB - all assembled with the slot cut. I did still have a physical interference with the ADC and the DHT header that I forgot to check with the mockup.
MQ Board as delivered. The Main board has images shown in this post.
Soldering the 0805 resistors which I had never done before.
Air Baffle
This is something I've been noodling around on back since a commentor asked about how I was planning to keep the sensors clean. My initial thoughts were just "stick the sensors above the range" but keep chewing on different ideas. A window could easily keep the visible light camera clean; but would block IR light for the Grid Eye. A zinc sulfide window is what FLIR and others use to pass 3-15 uM lightwaves through as a window on their IR sensors; but they are very pricey - > $250 on Edmunds Optics for a 1 x 1 CM piece.
I eluded to in my last post about a baffle design to draw air through and I have managed to implement it. It is a little box which provides physical barriers to the air sensors on the MQ board, then positive air pressure in front of the camera. This also incorporates a metal mesh filter taken from an actual range hood screen, and a charcoal filter right before the cameras to get all the other stuff out. It should keep things relatively clean. This was challenging to fit two filters, to cameras, one LARGE PCB and a fan into what ended up being a very tight space.
Images showing dual camera mount
Filter design.
Other work
I also created a screen mount to hold the 4D Systems touchscreen above the range. It was 3D printed and turned out very nice. I've taken significant strides in the controls and think I've basically covered everything I set out to do with this project. I've got some tweaking to do over the next week to fully implement the 4D Systems buttons and the Pi Camera but that shouldn't be a problem. I have also implemented texting using the Email node in Node Red. The second video shows a live demonstration of this and is very cool!
This video is about 6 minutes, but shows a good amount of the work that I've done. It covers the PCB assembly and troubleshooting, the baffle design, and a few other things.
This shows with everything powered up. You can see the user interface, the texting functionality, and explanations of off of that.
Upcoming!
I wanted to have a picture to show the final installed module in the range hood, but wasn't able to complete this tonight. Tomorrow I think I'll have this done and can call the project like 98% complete.
I'll post more details on the final once I have more time, but feel free to leave comments or questions below.
What do you guys think? How is this coming along? Let me know in the comments below!
Top Comments