direct wireless comunication without router
esp8266 as WiFi client
Pi as access point
UDP protocol on esp8266 to talk with Pi
python code to talk with esp8266 using UDP
python UDP implementation On Pi
https://wiki.python.org/moin/UdpCommunication
guide for setup Access Point on Pi
https://learn.adafruit.com/setting-up-a-raspberry-pi-as-a-wifi-access-point/overview
in esp8266 arduino IDE go to example select wifi--> wifiUDPSendReceiveString Example and change #include <WiFi.h> to #include <ESP8266WiFi.h> and Loadit to your nodeMcu..
for longer distance wire transfer
moze i bez otpornika. on u nekim slučajevima treba (za terminiranje linije u slučaju zadnjeg uređaja u lancu), ali kod nas je radilo i bez njega.
desna strana čipa je ista (napajanje i kabel). ja možeš dodati neki 100nF kond između Vcc i GND čist da malo isfiltrira napajanje.
s lijeve strane spojim zajedno RE' i DE (ovim se bira da li se signal šalje ili prima, ne može istovremeno oboje). za slanje signala, serijski TX dovedem na DI, a ova dva spojena pina spojim na +5V (receive disable, transmit enable). na drugoj strani, za primanje RO na čipu spojim na serijski RX, a ova dva pina zajedno na GND (receive enable, transmit disable).
