HC-11 433 Mhz Transceivers

Has anyone any experiance with these. http://www.ebay.com/itm/HC-11-433MHz-CC1101-RF-Wireless-Transceiver-RS232-TTL-/181494611302 Doco is pretty light on , and its unclear whether they implement some kind of error corrected link or are simply a raw half duplex transceiver, where the user has to do the work of error correction. Even so, for $4 cant complain.

The HC-11 uses the TI C1101 chip, which has hardware CRC error detection. Error detection is required for successful packet transmission, but it seems unlikely that error correction has been implemented.

Plenty of info on the TI web site about that chip, but who knows what features are used by the micro on the HC-11? There is some useful info here http://forum.hobbycomponents.com/viewtopic.php?f=74&t=1678

Thanks , I figured that error correction was not a likley option. Will have some next week so will find out. They are a better option pricewise than a pair of the el cheapo 433 Mhz ASK transmitter / receiver types.

Well having played around with these devices for a while, they seem to be as good as the very cheap 433 ASK modules that are commonly used, range wise, but are a lot easier to use, and being a Transceiver are bi directional. They dont have end to end error checking, but have some kind of integrity checking, so you either get what you sent or nothing at all. Data interface is simply serial ttl, and there is an AT command mode where you can change the modules paramaters. The Docs are a bit light on and the best I could find is here. http://www.seeedstudio.com/wiki/images/a/a8/HC11_User_Manual.pdf

The AT commands have to be sent from a Micro with no gaps between the chars. They cost around $4 on Ebay, but you have to hunt around a bit as the prices vary widely.

Mauried, thanks for the update. I was thinking of trying the ebay modules out.

If you could post simple working examples of transmit and receive code, I imagine that would be helpful to many people.

No code of any kind is needed. Out of the box the modules default to a 9600 baud piece of wire. ie if you feed data in at 9600 baud to one , it comes out the other, and vice versa. The modules themselves handle the reversing of the RF link which is 1/2 duplex. Whilst there are a lot of variables that can be configured, for most people and most apps you dont need to change anything. You can use either the hardware usart or Software Serial.