Category: VSCP

Serial port

Connect the USB cable to the board.  You will get a new CDC serial port. You can check which one you get with

ls /dev/tty*

Normally you get /dev/ttyUSB0 or /dev/ttyUSB1 or the like. To make them usable for you you should add yourself to the dialout group

addgroup user dialout

where “user” is your username. You can also do this manually in the /etc/group file or

chmod a+rw /dev/ttyUSB0

if you like brute force.

Loading code to the ESP8266

The ESP8266 CPU can be booted in three different ways:

• Flash Mode: default booting mode. Firmware is read and executed from the flash memory. Pins need to be set to: GPIO15=0, GPIO0=0, GPIO2=1
• UART Mode: used to program our board (through a Serial-to-Usb adapter). Pins need to be set to:  GPIO15=0, GPIO0=1, GPIO2=1
• SDIO Mode: loads firmware from an SDIO card? Pins need to be set to:  GPIO15=1, GPIO0=0/1, GPIO2=0/1

The boot process is described here.

Switching from a mode to another requires to reset the module while the pin states listed is set.

With the nodemcu board and esptool flash uploader all this is handle automatically but if you have another board you must handle this yourself.

esp-open-sdk

You find it here.

Fetch it

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

cd esp-open-sdk

Install it

apt-get install make unrar autoconf automake libtool libtool-bin gcc g++ gperf flex bison texinfo gawk ncurses-dev libexpat-dev python sed

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

cd esp-open-sdk/

make

echo 'PATH=$PATH:~/development/esp8266/esp-open-sdk/xtensa-lx106-elf/bin' >> ~/.profile

echo 'PATH=$PATH:~/development/esp8266/esp-open-sdk/esptool' >> ~/.profile

PATH=$PATH:~/development/esp8266/esp-open-sdk/xtensa-lx106-elf/bin
PATH=$PATH:~/development/esp8266/esp-open-sdk/esptool

I have installed the toolchain in

 ~/development/esp8266/ 

so change paths above for your installation folders.

Update it (when updates are available)

make clean
git pull
git submodule update

Firmware upload tool

pip install esptool

You find it here

cd ~/development/esp8266/esp-open-sdk/examples/blinky

Type

make

to build it. Remember that the paths above must have been set. You may get some warnings. No problem.

For your information. If you build from source code should be loaded like this:

• bin/0x00000.bin to 0x00000
• bin/0x10000.bin to 0x10000

That is just what we do here. Upload to your module with

esptool.py --port /dev/ttyUSB1 write_flash 0x00000 blinky-0x00000.bin 0x10000 blinky-0x10000.bin

No need to press any buttons during flashing. It is handled automatically by the USB DTR circuitry.

Now we are ready to do some real work for our VSCP system with the ESP8266.  If you rather prefer Arduino this howto may be the one you should go for instead of this one. Life is much simpler in the Arduino world. But the degrees of freedom is better if you do it all by yourself. The penalty for freedom is more problems of course. As always.

Another intro is here http://www.electrodragon.com/w/ESP8266_Open_SDK
esp8266 wiki is here.

Part 2 will follow.