Week 11: Networking with ESP8266 Using Atmega

For this week I set out to make a board that will show realtime MBTA bus arrival times using the ESP8266 wifi module and a LCD. Seemed doable. People of the internet have been excited about the ESP8266 lately. Here is a snapshot of google trends for searches for esp8266 vs couple of other arduino favorite processors.

That’s the rough plan. I run the atmega32u4 and the LCD at 5V. The ESP8266 I power at 3.3V using a regulator. As for the logic chatter, I feed the 3.3V output of the ESP8266 to the atmega and I feed the output of the atmega through a voltage divider to bring it to 3.3V suitable for the ESP8266. This turned out to be a mistake that I will discover 15 hours later.

Mounting the lcd

I got a package from adafruits.com that I am modifying. First copy the package by

• opening target library
• selecting the device in the main window nav tree
• right-click copy to library

To get the mill to drill holes where needed, I am using the circle tool to draw filled cirlces (width 0).

ESP8266 package

I am making an eagle package and device for esp8266 header.
Steps:

• copy over a suitable part from another library (MA04-2 from con-lsb, a 4×2 header)
• open my library
• right click on part from source library
• click copy to library
• rename the package withrename MA04-2.pac ESP8266_HDR_REVin the command bar
• click package and select the package to edit
• get rid of all the crap that’s there (outline etc)
• add circles in the milling layer
• use name tool to give names (GND, RST, GPIO2, etc.)
• added some helpful text in the document layer
• create a new symbol (ESP8266)
• use pin tool to lay down 8 pins in row
• use name tool to add the same names I used in the package step
• create new device (ESP8266) (click device, pick a new name)
• use the place tool (plug thingie) to add the newly created symbol
• click new on the lower right to add the package
• click connect and go through and connect all the pins with all the pads

Milling

Prep for milling

• display none top pads to get the traces
• display none milling to get the milling guides
• display none outline to get the outline

I separated the holes and outline to make sure the board outline doesn’t get cut before the holes are drilled.

Now it looks like I am just shy of the mill diameter for the holes. I have to lie about the tool diameter again (0.75mm instead of the actual 0.79mm)