I have seen toy remote controlled cars and other toys available for real low prices. How do they implement RF communication?
I mean to say when I search for RF units to buy they come at a pretty high prices. So obviously there is some way of implementing RF at lower prices.
Does any body have information on how toy manufacturers get RF working at such low prices? Of course given the fact that I don't want much communication between the remote and the sensor.
Most of the RF transceivers used in toys (and other wireless devices, like garage door openers and car locks), use proprietary protocols. Because they are not using one of the standard protocols like Bluetooth or Zigbee, there are no royalties to pay so the RF transceivers can be cheaper.
Both the proprietary protocols and standard ones like Bluetooth and Zigbee use the unlicensed ISM (industrial/scientific/medical) bands. It is the licensing of the protocol that is the cost factor.
When you buy a module from SparkFun or another supplier, it is more likely to be using on of the standard protocols, and the licensing fee has been factored into the cost.
RF isn't very expensive, the pre-built modules that are sold are generally low volume, high margin devices.
For instance the ember EM351 is a cortex m-3 microcontroller with a zigbee radio on board and runs around $4.50 in volume. Chip antennas are only about $0.50 for such a part so the overall cost isn't that high. There are cheaper SoC's with lower powered microcontrollers out there as well. For example the rfPIC12F675H is a PIC microcontroller with a 900Mhz radio on board and runs about $2 in volume.
Part of the reason the modules tend to be expensive is that they get an FCC modular certification with puts the module under test without any sort of enclosure, as a result they require shielding on the PCB and other higher cost controls to pass.
Some of them don't use RF. They use infrared. I saw a tear-down at ESC in Boston of a helicopter. The IR detector is much smaller and lighter than RF parts. Also, my son has a micro-mini RC car. It uses IR.
Also the code to implement the serial IR communication requires much less code, so a smaller micro is needed.
I sell the RFM70 for $4.41 in singles. I am sure to make a profit, so you can guess what those modules cost at the moderate amounts I buy. Contact the manufacturer for the bare chips in large quantities, and put them on your own PCB, and the price will be even lower.
Many of the cheapest toys don't push very much through the RF link. The mere presence or absence of a single frequency can convey one bit. It only takes two such bits to implement the 'J' control scheme (forward or back-and-turn) - and when the input source is a human being playing with a remote, the frequency requirements for these bits is very low; more than maybe 10 or 12 button presses per second is a challenge. A cheap toy could probably even have up to 100msec jitter in response time, and no one would notice.
The upshot of all this is, it doesn't take a high performance radio system to accomplish the requirements.
