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).
I am making an eagle package and device for esp8266 header.
- 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 with
rename 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
For more detail: Week 11: Networking with ESP8266