Customer Happiness Check-In
|genovese basil||parsley||sweet basil||stevia||stevia||lettuce|
|genovese basil||thyme||sweet basil||stevia||stevia||kale|
YIPPEE! I’m seeing growth in all but one of the stevia. Maybe it is a late bloomer. Curiously, I have the same feeling for the stevia being a late bloomer as I had when one of my kids took a long time to figure out how to walk. Too good at rolling to bother :-).
Schematic for the Grow Chamber Sensor Puck
I haven’t spent time working on the Grow Chamber sensor puck so I’ll put some time into it now. But first…
Thanks To Those That Went Before
The Kicad Team – The KiCad EDA has come a long way. KiCad has enabled so many of us to get into designing and building our own PCBs. The team that does this work is amazing. THANK YOU.
Contextual Electronics – Thanks to Chris Gammell’s Contextual Electronics, I have the confidence and ability to design and build PCBs. Since I knew nothing about electronics before Contextual Electronics – after all, it is not something a woman in my age group would be encouraged to do – it is hard to describe the feeling of happiness I have in being able to design my own circuits. THANK YOU.
ams and Silicon Labs – Both ams (manufacturer of the CCS811) and Silicon Labs (manufacturer of the Si7006) provided schematics which made it far easier for me to layout a schematic. THANK YOU.
The Kicad schematic I discuss below is located at this GitHub location.
The sensor puck will monitor CO2, temperature, and humidity. To do this, I will use two chips:
- The CCS811 for CO2 monitoring (I copied the data sheet to this GitHub location).
- The Si7006 for monitoring temperature and humidity (data sheet).
The first thing I am doing is upgrading Kicad. It has been awhile since I have used Kicad. The current Mac version I am running is 4.0.3. The version on the OS X downloads page is currently 4.0.5. There is both a main package and an extras. I just downloaded the main package for now.
I’m going to start a schematic that is only one page. I do not see the need to have a hierarchical structure. To lay out the CCS811, I’ll use the schematic in the CCS811 ams Eval Kit Manual (I copied the PDF to this GitHub location).
Hmmm…one thing I didn’t see on this schematic were 10K pull-up resistors on the SDA and SCL lines. I’ll add these.
I’ll use the schematic in the Si7006 data sheet for the layout of the Si7006 chip.
Creating a schematic is a great way to get a deeper knowledge of the chip. I am grateful for the schematics provided in the data sheets. They are a great jumping off point!
Stuff I’m doing on the schematic:
- I copied the ADDR circuit which pulls this pin to GND using a 4K7 resistor. From the pin assignment documented in the data sheet (I copied the data sheet to this GitHub location), when the ADDR is low, the I2C address is 0X5A. When I write the firmware, I’ll use 0X5A as the I2C address.
- I’ll wire the AUX, PWM, and SENSE in the same way these pins are wired in the above schematic. I don’t think I will be using the optional chip ambient temperature sensing. However, it is of little cost to add the two resistors so why not?
- One of the resistors is an NTC thermistor. Which one to use? I am happy to see the eval kit’s BoM:
The CCS811 notes several application notes. Sadly, I couldn’t find a way to access them so I sent a not to ams support (emailing firstname.lastname@example.org):
I’m seeing an increased risk of using the CCS811. The chips themselves have a lead time (Digikey has about a 3 month lead time), and I can’t get access to documentation ams says is available. I need to keep an eye on that!
- Layout the components in eeSchema
- Get the components in line with requirements to use the BoM generator I created awhile back. From this blog post, two properties are used by the python program that will generate the BoM from eeSchema info:
- Component Value
- Part Number (labeled as PN). The PN can be one of three things:
I added the digikey PN to the CCS811 component:
I populated the Value and PN fields for each component in eeSchema.
The current Schematic the only thing missing is a connector:
And…well, I truly enjoyed my time spent in eeSchema. That’s it for today!