A little long but please read
Dear All,
First of all i'd like to thank you so much for providing me with all the information and help. Now, i am at the stage of reviewing and aggregating those things you told me. So, i thought a last review and confirmation would be good for a double check and better understanding.
As you remember my project is as follows (or have i ever told about it?):
Two keypads having a couple of buttons on them to control two remote devices/machines (an agitator and an analyzer) by means of RF signals in "two" closed areas (mixing room and laboratory) of a waste treatment facility. I am responsible to develop the keypads (simple looking ones) and the receivers having interface with the controllers (industrial PCs embedded into the machines). ***I am just a chemical engineer with a very few knowledge about electronics ***
So, the followings are what i understood from your advices:
1. I'd need two microcontrollers. One is for transmitting device (i.e. keypad) and one is for receiving device (receiver).
2. I'd need a flexible PCB for keypad so that i can solder/mount all the components and buttons including PIC16F84.
3. I'd need a normal PCB for the receiver so as to mount the components.
4. I'd also need RF components with "anti-collision tags" so that other RF devices (such as a radio etc.) would not interfere with my keypad and distort the signals. There should not be any interference among my keypads as well. A reminder: i will make two keypad since i have two rooms in the facility.
5. I do not need an RFID because i do not need a barcode or a telemetry kind of thing. I will not trace anything or i will not assign more than one transmitting device to one single receiver. (and that's why i do not need RFID...is it reasonable?)
6. If i use "higher" frequency RF, then my receiver can sense the signal coming from "longer" distance. (Is this correct?)
Now, here are my questions:
1. One of you told me that "All the ID does is to prevent the receiver from responding to the wrong signal coming from a wrong transmitter."
This sounded interesting to me. Because i will make two transmitters with the same exact frequencies. I will also make two receivers for those two transmitters. I mean all the two transmitters and two receivers will be same with same features. One receiver will be attached to an agitator in one room (mixing room) and the other receiver will be attached to an analyzer in another room (laboratory room). However, while i am using my transmitter for the agitator (in the mixing room of the facility), i do not want other guy comes from the lab. room with that other transmitter (the one which is used for analyzer and remember it has the same features of my transmitter) and use the device. I mean it would be so bad if he uses his keypad (transmitter) and send wrong orders to the receiver on the agitator while i am using my transmitter to send some signals (orders) to the same receiver. (He can manage his analyzer but he can not manage the agitator and if he gives wrong signals in the room in presence of me or while i am out. In the same manner, i can manage my agitator but i do not know how to manage the analyzer. So, it could be so devastating if somehow i use my transmitter in lab. room unintentionally to send signals to the analyzer.) How should i prevent this? By anti-collision? or by an RF ID?
2. Think of two cars of "same" brand and "same" model. Say, two Mercedes SLK200 cars with RF carkeys to open the doors. And assume one of them is mine (ah i wish
) How come my RF key does open the doors of my Mercedes SLK200 but can not open my friend's Mercedes SLK200? Is it because of RFID? is it because of what? I mean how come the receiver on the car identifies that the signal is coming from the right (correct) transmitter?
3. On some printed manuals, i read the following statements: "Independent product ID for each product. 256 ID and RF-technique to prevent interference" or the statements like: "32 ID memories with transmission range up to 5 meters to prevent interference among RF devices." or statements like: "Shared RF receiver using one I/O port for various RF devices" or statements like: "Shared RF receiver with self-learning function to memorize and lock on specific RF devices" What does all the jambo-mambo mean? I am CONFUSED
I would be really very very happy if you can give answers to my questions, correct my mistakes and pray for me
Thanks a lot. Take care all.
Marv.
ps: Please do not ask me to make my transmitter with different frequencies so as to avoid collision etc. because i should use the same frequency for both of the transmitter. There is a reason behind it.