hello,
im working 12 arduino device in one i2c bus.one master and all others are slave(12 remote location) .all slave devices send data to
master and display l2c lcd.its working prefect .
all slave devices include some sensors and controlling relay and i newly add Ethernet shield with SDcard and another arduino uno board (yes its are slave).
now i want to doing
- displaying slave sensors values on webpage
- displaying slave relay stute (on/off)
3.control relay on web(local network )
i was did a read all sensors value in master device but i cant send it to master to slave Ethernet arduino board . i try to master send data and slave "Wire.onReceive(receiveEvent)" but i cant read that data.
any one have idea to doing this or can i use Wire.requestFrom() on slave device ask data to master device
very sorry for my bad English
You have a Arduino board as I2C Slave and with Ethernet and SD card ?
Is that an Arduino Uno ? it runs very quick out of memory when you use both the Ethernet and the SD card.
For a webpage, often an Arduino Mega 2560 is used.
Did you create a webpage in ram ? Or did you create a large buffer in ram ?
Can you show us your sketch ?
The I2C-bus and the SPI-bus for Ethernet and SD card can be used together without problem.
it arduino uno board and w5100 Ethernet shield with webpage on SD card .
and yes your absolutely right about ram. im ruining on it with low memory warring.
but my thing is i need to requesting data form master .(when slave request data master send data to slave)
is it possible to doing?
With an interrupt it is.
Add an extra wire from the Slave to an interupt of the Master. In the Master set a flag (a boolean variable) when the interrupt routine is called, and check in the loop() for that flag. That way the Master knows that something should be done and can send data to the Slave.
This will cause a delay, so it is not a very good solution.
Or you can send that data every minute or every 5 seconds. In the Slave you show the latest value on the webpage.
I have a Master that runs the webpage (with the html file and small pictures on SD card). The Master is a Mega 2560 board with W5100 Ethernet Shield. All Slaves are connected with I2C.
When a webpage is requested, the data is retrieved from the Slaves at that moment. It makes the webpage a little slower, but it is not a problem.
thank you very much this very good idea ,i try it to pass single when webpage request data.