I am using RS485 links with CAT5E wiring at 9600bps for a home automation project. The system comprises of sensors, switching modules and other input devices all communicating through the RS485 network.
I am now in the process of adding wireless capability to the above components by replacing the RS485 transceiver link with (or adding) some kind of wireless link. The speed remains the same and the required range should reach up to 20-30m. Obviously the size of the additional module should be kept to a minimum possible.
Which type of wireless module would you recommend based on the above application? I was thinking of the nRF24L01 module, however I am reading some mixed results from other users.
Amount of data per packet?
Number of packets per time frame?
Range?
Reliability?
Budget?
How much work are you willing to do to deal with any of these issues?
Amount of data per packet?
Number of packets per time frame?
Range?
Reliability?
Budget?
Each frame has a variable number of bytes between 10 and a max of 80 bytes. The baud rate is 9600 bbs.
The first byte in each frame defines the number of bytes that will follow.
The frames are transmitted asynchronously and a device is normally responding to interrogation by another device. For example a relay module responds to a switch-on command by a user input module.
As mentioned before, required range should be between 20-30m max.
Regarding reliability I am using CRC checks to verify frame integrity before execution of any commands. If crc fails the frame is dropped. If no response is received the sender repeats the frame up to 5 times.
Budget:.. Hmm... I would expect something not more that $10-15 each.
If you dont want to use NRF24L01s , then there isnt much around that fits your budget.
Some more detail would help as well.
eg does each sensor have an Arduino or some kind of Microprocessor to create the data format.