Downloading code to ESP8266 in Ubuntu

In last article I talked about setting up the SDK in Ubuntu, if everything goes well, you may can compile the code and got the binary code generated.

To download in Ubuntu is every simple, you just need to install the downloading tool and run it. There is a folder in the esp-open-sdk, which is the open source part of the whole SDK, named 'esptool'. inside the folder there's a Python program 'esptool.py'. If you have Python installed on your computer, you probably can use this tool. But for me sometimes it gives me confusing error message. I have two laptops both with Ubuntu 16.04, it runs well on one of them but on the other it says 'ImportError: No module named serial'. I don't know Python so I'm not able to figure out the problem. I hope you don't encounter this.

There is another way to do it. Since Ubuntu 12, the 'esptool' has been in the official repository and it's still there in Ubuntu 16. All you need to do is install it using the 'apt install' command.

$sudo apt install esptool

Yes, it's that simple. After this you'll have the ESP8266 downloading tool installed on your computer and that's a binary code you don't even need Python environment.

There are more functions than downloading in this esptool, you can find them out using 'man', Yes! yet another benefit to install esptool from the Ubuntu repository. To see the user manual, type :

$man esptool

Briefly, the command format is:
esptool -cp 'serial port' -ca 'address1' -cf 'file1' -ca 'address2' -cf 'file2' ....  (without the quote character)

For connecting the ESP8266, please see this article : Connect ESP8266 in Ubuntu

If you have multiple USB tty devices connected, it would be difficult to know which is which by just seeing the /dev/ttyUSB* list. A shortcut to sort it out is to use the 'dmesg' command. It will output all the system messages since the computer was been turned on, but a grep will filter unwanted out. Unplug your ESP8266 and connect again, then type:

$dmesg | grep tty

The latest message about tty device will be your ESP8266 and you'll know which ttyUSB number it's at.

A real download command would look like this:

esptool -cp /dev/ttyUSB0 -ca 0 -cf eagle.flash.bin -ca 0x10000 -cf eagle.irom0text.bin -ca 0x3fc000 -cf esp_init_data_default_v08.bin -ca 0x3fe000 -cf blank.bin

Building the ESP8266 SDK in Ubuntu

The ESP8266 is built upon Linux entirely, the compiler and linker are both based on GCC, and even the downloading tool is also a Linux application. But for some unknown reasons, Espressif chooses to provide its SDK in a Windows favor. In their official guides, you need to install a virtual machine in Windows and then download an entire Lubuntu image which contains the SDK.

For someone who uses Ubuntu more than Windows like me, this simply doesn't make sense. And Espressif won't tell you how to build the environment in linux at all. If you let me pick a company with bad documentation, Espressif must be in the top 3.

I finally figured it out after a lot of searching and trying, and I would share it here.

At first, it should be made clear, which Espressif has failed to do so, the SDK is consist of 2 parts, the esp-open-sdk and the ESP8266 SDK. The esp-open-sdk is complete open source, containing the compiler and other utilities. This part can be downloaded from Github as source file, and then compiled locally. Thanks for pfalcon for doing this great job. Just choose where you want to install it and run:

$git clone --recursive https://github.com/pfalcon/esp-open-sdk

 You should get a dir named esp-open-sdk, and then enter the dir and run:

$make

If there are any missing dependencies the make program will give an error message and you can just follow the hints it gives to fix that. There are detailed instructions about the install on Github. The compiling will take quite a while (tens of minutes) if your computer is not fast enough.

The next step, is to install the ESP8266 SDK itself. This part is related to the ESP8266 chip and not completely open source. It contains some proprietary libraries. This part should be downloaded from Espressif's official web site. It would be something like ESP8266_NONOS_SDK-2.2.0 or so. You can put the downloaded directory anywhere you like, but not in the esp-open-sdk.

An important step, don't forget to add the /esp-open-sdk/xtensa-lx106-elf/bin/ to your PATH:

$export PATH=$PATH:(your full /esp-open-sdk/xtensa-lx106-elf/bin/ path)

Now we are ready to compile the examples. There is another pitfall hiding there which Espressif didn't tell you and will make you crazy. The examples in the SDK can NOT be compiled unless you move them to the upper folder!

All the examples are in the /ESP8266_NONOS_SDK-2.2.0/examples/ ， for example, the IoT_Demo example is in /ESP8266_NONOS_SDK-2.2.0/examples/IoT_Demo/ . If you would like to compile this example, you have to MOVE it one level up, parallel to the 'examples' folder, so the project compiled must be at a folder like /ESP8266_NONOS_SDK-2.2.0/IoT_Demo/ .

At the correct location, inside the IoT_Demo, just run:

$./gen_misc.sh

I hope this could help you.

Connect ESP8266 in Ubuntu

I received my ESP-launcher board a few days ago, 2 ESP8266 module and a ESP32 dev kit have also been ordered but I decide to leave them for later use, would stick to the launcher board at this stage.

The SDK for ESP8266 is based on linux, the user manual suggest you to install a virtual machine in Windows and do your job under windows. I don't know why they do this, probably because their download tool is for Windows only ? For me that doesn't make sense. I won't waste my hard drive space to install a virtual machine while I already have a Ubuntu installed as a dual boot.

The simplest way to play with a ESP8266 is to use the AT command, you just need a terminal and a USB port. There is already a USB-UART chip FT-232 on the ESP-launcher board, and the good news is Ubuntu has built-in driver for it.

You don't need to turn on the launcher to check the FT-232's status. Connect the USB cable and go to the terminal in Ubuntu, use this command to check if the USB-UART chip has been recognized:
lsusb

See the second one from the last : Future Technology Devives International, Ltd FT232 USB-Serial (UART) IC

When it's correctly driven, you will get a new TTY device and that is the AT terminal to use. Use "ls /dev" command to check the devices and search for "ttyUSBn", on my computer, it's ttyUSB0.

Unfortunately, Ubuntu doesn't come with a proper terminal software to communicate via these serial ports, you have to download the "minicom" software. It's easy just use "sudo apt-get install minicom" form the terminal.

run minicom in the terminal, you have to use "sudo minicom" otherwise it will not run. For the first time, use "sudo minicom -s" to enter setup and set the serial port to the USB, be sure to set it to 115200, 8N1, like this:

When everything is set, turn the ESP-Launcher on, ta-da! you see the "ready!" from the ESP8266!

Now let's try some AT commands: AT+GMR displays the version information the ESP8266 chip, and AT+CWLAP displays the wifi hotspots arround:

Remember, you have to use Ctrl-m + Ctrl-j at the end of AT command, or use
ENTRE+Ctrl-j , seems the ESP8266 needs a Windows like end-of-line mark.

Connect to the WiFi :

That's it! You can't do much with just a terminal and ESP8266, to have more fun you have to do some programming, either program the ESP8266 itself or connect an external MCU, I'll try it later and write a post then.