#342 MorseBlinky

Building code for an ESP-01 with the ESP8266 core for Arduino and demonstrate with a simple morse code blinker.

Here’s a quick video showing it in action..

Notes

The ESP8266 core for Arduino brings support for ESP8266 chip to the Arduino IDE.

That means being able to write C++ sketches for the ESP8266 as easy as developing for an Arduino.

This project is a quick test to see how it all works. Objectives are minimalist:

using the most basic ESP8266 board: an ESP-01
just blink the built-in LED with a morse code message

The MorseBlinky.ino sketch blinks a Morse code message on the built-in LED.

The sketch can be compiled unmodified for either an ESP8266 board or an Arduino.

There may be one difference required depending on the specific board: whether the built-in LED uses active-high or active-low logic. Tthe specific ESP-01 board I have uses active-low logic, whereas most Arduino boards I’ve seen use active-high. This can be controlled with the ACTIVE_LOW_LED_LOGIC setting in the sketch.

Programming Setup

I’m using a LEAP#194 DIYDevBoard to host the ESP-01 module, and a cheap CH340G-based USB to UART adapter. With the correct drivers installed, it shows up in the Arduino IDE ports list.

Uploading a Sketch

Selecting the Generic ESP8266 board and correct port:

board_settings

The ESP8266 needs to be put into flash mode to accept the program upload:

connect usb to dev board
set flash mode dip switch
power on the esp-01 (or toggle reset dip switch)
arduino ide - click upload sketch

Note: this will of course wipe whatever image is already on the chip.

Here’s the transcript of the programming step, performed by the esptool.py that is integrated in the ESP8266 core for Arduino

Sketch uses 222161 bytes (51%) of program storage space. Maximum is 434160 bytes.
Global variables use 31528 bytes (38%) of dynamic memory, leaving 50392 bytes for local variables. Maximum is 81920 bytes.
/Users/paulgallagher/Library/Arduino15/packages/esp8266/tools/esptool/0.4.9/esptool -vv -cd ck -cb 115200 -cp /dev/cu.wchusbserial14530 -ca 0x00000 -cf /var/folders/28/_tsmhg4172s_wy7vswfkzq9h0000gn/T/arduino_build_533772/Blink.ino.bin
esptool v0.4.9 - (c) 2014 Ch. Klippel <ck@atelier-klippel.de>
  setting board to ck
  setting baudrate from 115200 to 115200
  setting port from /dev/tty.usbserial to /dev/cu.wchusbserial14530
  setting address from 0x00000000 to 0x00000000
  espcomm_upload_file
  espcomm_upload_mem
opening port /dev/cu.wchusbserial14530 at 115200
  tcgetattr
  tcsetattr
  serial open
opening bootloader
resetting board
trying to connect
  espcomm_send_command: sending command header
  espcomm_send_command: sending command payload
trying to connect
  espcomm_send_command: sending command header
  espcomm_send_command: sending command payload
  espcomm_send_command: receiving 2 bytes of data
  espcomm_send_command: receiving 2 bytes of data
  espcomm_send_command: receiving 2 bytes of data
  espcomm_send_command: receiving 2 bytes of data
  espcomm_send_command: receiving 2 bytes of data
  espcomm_send_command: receiving 2 bytes of data
  espcomm_send_command: receiving 2 bytes of data
  espcomm_send_command: receiving 2 bytes of data
Uploading 226304 bytes from /var/folders/28/_tsmhg4172s_wy7vswfkzq9h0000gn/T/arduino_build_533772/Blink.ino.bin to flash at 0x00000000
  erasing flash
  size: 037400 address: 000000
  first_sector_index: 0
  total_sector_count: 56
  head_sector_count: 16
  adjusted_sector_count: 40
  erase_size: 028000
  espcomm_send_command: sending command header
  espcomm_send_command: sending command payload
  setting timeout 15000
  setting timeout 100
  espcomm_send_command: receiving 2 bytes of data
  writing flash
................................................................................ [ 36% ]
................................................................................ [ 72% ]
.............................................................                    [ 100% ]
starting app without reboot
  espcomm_send_command: sending command header
  espcomm_send_command: sending command payload
  espcomm_send_command: receiving 2 bytes of data
closing bootloader

Construction

Breadboard

Schematic

Build

Credits and References