now that the I2C communication module is stable and i already completed the core logic process of the module, time to move on with starting to develop the wireless communication module using NRF24L01+.
as a base for the module, i'll be using the latest libraries RF24 and RF24Network done by maniacbug and TMRh20 in github. i did an initial test of the libraries early this morning by compliling (using UNO R3) the sample program helloworld_RX for the said libraries and the program size is already 8.3K bytes. it already exceeded the 8KB size of one of the MCU i'm planning to use. really need to review how the functions in the libraries was constructed and determine the possible options to reduce the size of the wireless module to a manageable level.
... Sketch uses 8,318 bytes (25%) of program storage space. Maximum is 32,256 bytes.
... Global variables use 653 bytes (31%) of dynamic memory, leaving 1,395 bytes for local variables. Maximum is 2,048 bytes.
i also need to verify and confirm if the nordic Enhanced ShockBurst method will work with the existing libraries. i'm assuming it should as it's the best feature of the NRF24L01+ chip ... cheers
Boo!
Hi Boo,
You may or may not use the library kung masyado malaki program space ang magagamit. usually naman hindi nagagamit lahat ng APIs na nasa library. you can make your own API or gawa na lang kayo ng header and icopy nyo na lang from library yung sa tingin nyo ay magagamit nyo sa firmware nyo. Sa experience ko naman sa NRF24L01, effective range is 10 meters only (line of sight). move a little more farther medyo may problema na sa reception. lalo na kung may mga concrete walls pa. i remember dati pinagawa ako ng boss ko ng buzzer system para sa isang quiz bee sa MOA, halos di ako nakatulog ng ilang araw dahil sa pagresolve sa reliability ng transmission using NRF. eh kailangan pa naman realtime ang response kapag nagpress ng button ang isang contestant. tapos halos sabay sabay sila magpress ng buzzer halos sabay sabay din darating sa main controller ang data packets. i ended up using xbee instead hehehe. xbee din ginamit ko sa wireless scoreboard sa gym ng national university. anyway, hindi naman ganun kabigat ang wireless data traffic sa application nyo so you can use NRF, for short distances only. lagyan nyo na lang ng retry sa part ni node and ackowledge sa part ni host or vice versa depende sa requester.
your right about the 10m max distance. my initial test of the NRF was about 7-8m in my house because of the steel deck of the floor slabs. worst scenario if i need more distance is to use a simple repeater to extend the range if its only 1 unit. if not, i noted in my documentation before to look at the possibility of using a star network topology to receive and forward the msg using another node in the middle. i saw it once in SG in a demo of a WISP setup in a telecoms convention. the downside is the logic of the program will be tough to revise + the overhead in the network associated with that functionality. hopefully i don't have to do it and just use a wired connection for end nodes that are in a distant location.
i'm still looking for some library in the internet that is small enough for my need. if i can't find one, then no choice but to make my own copy of the library with only the things i need for my setup ... cheers
Boo!
