DIYDevBoard

#194 ESP8266/DIYDevBoard

a DIY devboard for an ESP-01 ESP8266

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Notes

With the funding of the MicroPython on the ESP8266 campaign, my interest in the ESP8266 is rekindled.

I have an ESP-01 module that I'd played around with before, but I was a bit tired of wiring it up a breadboard again. So here are my notes on a little "devboard" I whipped up on a 4x6cm protoboard and hot-glued to a business card holder.

Now it's plug'n'play - add power and plug in my CH340G USB adapter and I'm good to go.

Features

This is what I've included on the board:

• LD1117 3.3V regulator circuit (power from a barrel jack)
• BidirectionalLevelShifterModule to convert 5V serial signals to 3.3V
• fixed pull-up on the CH_PD chip enable
• pull-up resistors on GPIO_0 and RESET, with pull-down toggle switches
• breakout pins for GND and GPIO2
• 2x4 socket for the ESP8266

Switch Controls

There are two switches on the board (I used a DIP switch module). These are for controlling the reset and GPIO_0 lines. The normal position is "off".

Switch	Pin	Off	On	Usage
SW1 (left)	GPIO_0	Pulled high	Pulled low	Pull low to enter flash mode
SW2 (right)	RESET	Pulled high	Pulled low	Toggle low then high to reset the board

Test Drive with espy.rb

To verify everything was working OK on the devboard, I plugged in the ESP8266 with default firmware and I exercised it with SerialTest/ruby. Here's a test of getting the time:

$ ./espy.rb /dev/tty.wchusbserial14540 get http://www.timeapi.org/utc/now
ESP8266 Client initialised for : /dev/tty.wchusbserial14540
            connection options : {"baud"=>9600, "data_bits"=>8, "stop_bits"=>1, "parity"=>0}
                       signals : {"rts"=>1, "dtr"=>1, "cts"=>0, "dsr"=>0, "dcd"=>0, "ri"=>0}
Waiting to warm up the connection..
AT+CIPSTART="TCP","www.timeapi.org",80

OK
Linked
AT+CIPSEND=93
> GET /utc/now HTTP/1.1
Host: www.timeapi.org
User-Agent: EspyClient/0.9.2.4
Accept: */*
SEND OK

+IPD,277:HTTP/1.1 200 OK
Date: Mon, 07 Mar 2016 17:19:38 GMT
Connection: keep-alive
X-Frame-Options: sameorigin
X-Xss-Protection: 1; mode=block
Content-Type: text/html;charset=utf-8
Content-Length: 25
Server: thin 1.5.0 codename Knife
Via: 1.1 vegur

2016-03-07T17:19:39+00:00
OK
AT+CIPCLOSE

OK
Unlink

Test Drive with the esptool

esptool.py requires the board to be in flash mode:

• SW1 "on" to pull-down GPIO_0 (flash mode)
• SW2 toggled on then off (reset the baord)

Then the basic esptool.py commands to interrogate the board work fine:

$ esptool.py --port /dev/tty.wchusbserial14540 chip_id
Connecting...
Chip ID: 0x009ccdd2
$ esptool.py --port /dev/tty.wchusbserial14540 flash_id
Connecting...
Manufacturer: c8
Device: 4013
$ esptool.py --port /dev/tty.wchusbserial14540 read_mac
Connecting...
MAC: 18:fe:34:9c:cd:d2

Construction

Here's the equivalent breadboard circuit:

And schematic:

My rough 4x6cm protoboard layout:

The end result:

Credits and References

• esptool.py
• LEAP#134 BidirectionalLevelShifterModule
• LEAP#154 SerialTest - my first test of the ESP8266, with more details of board use
• LEAP#152 PowerLD1117 - LD1117 circuit and notes
• ..as mentioned on my blog