K1WifiGateway

Program for using ESP8266 to hack a certain 6LoWPAN to WiFi bridge system to use O-MI. Data is sniffed from a serial connection.

This program creates Open Messaging Interface write requests to following Open Data Format paths:

• Objects/K1/Gateways/ : Information about this hacking program
• Objects/K1/ : Received sensor information from sensor box installed at room name

Installation to an ESP8266

Getting a certificate and private key

Certificate and key need to be in unencrypted (empty passphrase) DER format.

Example for making keys: generate the private key (a 1024 bit key is used in this example)

> openssl genrsa -out my_private_key.pem 1024

convert the private key into DER format

> openssl rsa -in ./my_private_key.pem -out ./my_private_key -outform DER

generate the certificate request using the previously generated private key

> openssl req -new -key my_private_key.pem -out my_cert_req.pem

get the certificate from Certificate Authority (see other guides if you are managing your own CA)

convert the certificate into DER format

> openssl x509 -in my_cert.pem -out my_cert -outform DER

Then you can use SPIFFS or convert the keys to C code header with

> xxd -i client.crt > MyCertificates.cpp

> xxd -i client.key >> MyCertificates.cpp

Compiling

1. Run ./setup.sh
2. Install the Arduino for ESP8266
3. Depending on installation type, fix the ESP_ROOT in ./Makefile to point to your installation directory.
4. Depending on your target ESP8266 module, fix other settings in the top of the Makefile
5. $ make
6. $ make upload for uploading the program to ESP8266 connected to UPLOAD_PORT

OTA update

This project supports OTA update from the target server via secure HTTPS. This program ensures by default the identity of the server and sends its own client certificate to server for authentication, so unknown users cannot steal our client certificate from the update image.

To update:

1. $ make clean (otherwise the saved build time might be wrong)
2. $ make version
3. The image needs to be copied to the target HTTPS server from /tmp/KMEG-WSN-OMI-bridge/KMEG-WSN-OMI-bridge.bin
4. The WHOLE VERSION STRING is sent by the esp when looking for updates and can be compared to the new one
5. This esp program checks updates only on boot.
6. Check that the program updated and is not in a reboot loop (update shouldn't take more than 5 mins)

Our current server setup has the image on path /opt/k1update/KMEG-WSN-OMI-bridge.bin and requires modifying and reloading the nginx site config. This all is handled by an update script that can be run by make httpserver_upload if Makefile SSH_UPLOAD_SERVER is configured right.

Hardware setup

SERIAL CONFIGURATION:

Serial pin configuration can be changed in the Makefile. The default configuration is below, NodeMCU pin name is in parens.

Description	Transmit(NodeMcu)	Receive(NodeMcu)
Serial UART0: Usb,	GPIO 1 (TX)	GPIO 3 (RX)
-DSWAPSERIAL0 puts Serial to	GPIO 15 (D8)	GPIO 13 (D7)
Serial1 UART1: RX from flash	GPIO 2 (D4)

Use Serial1 for debug transmission (it can only transmit) and Serial for hacking the bridge. Now GPIO 1 is not used but is connected to usb serial for debugging, (not needed for production) Connection to wifi-bridge can now send AT commands and receive everything TinyOs is sending but cannot communicate to TinyOs MCU, which is not needed. Also everything sent is also echoed back. NOTE: Not good, TX is High when not transmitting? => requires modifications to the original bridge

USB Host        ESP8266               WizFi220        TinyOs MCU
USB RX <---+---< USB     TX >         < TX >----------> RX                
           |   < GPIO 15 TX >         > RX <-----+----< TX         
           `---< GPIO 2  TX >                    |  
               > GPIO 13 RX <--------------------´  

GATEWAY CONNECTIONS SUMMARY:

Header is the text marked row of islands next to WizFi220 chip.

1. VCC ESP <--> VCC header
2. GND ESP <--> GND header
3. GPIO13 (D7) ESP <--> TX header
4. GPIO04 (D2) ESP <--> RX header

WizFi connection replacements:

1. GPIO31 WizFI220 pin44: Cut before resistor (near MCU) and attach MCU side to GND (keep the resistor on the MCU side)
2. EXT_nRESET WizFI220 pin35: (It's the extra wire; no pcb trace) Cut and attach MCU side to GND

OTHER CONNECTIONS:

Table for ESP boot mode pin configurations. for restarting in case of crash

D8 GPIO15	D3 GPIO0	D4 GPIO2	Mode
0V	0V	3.3V	Uart Bootloader
0V	3.3V	3.3V	(RE)BOOT SKETCH, use this configuration
3.3V	x	x	SDIO mode (not used for Arduino)

GPIO2 (D4) is already connected to TX for debug output, TX is connected to VCC via 10k resistor in many boards.

In other words, connect (use 10kOhm resistors for the safety of your ESP):

1. GPIO15 (D8) <--> GND
2. GPIO0 (D3) <--> VCC
3. GPIO2 (D4) <--> GPIO1 (TX)