RedBee -automotive-

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I am planning on using a redbee reader as my RFID solution to start me vehicle. My current wiring diagram has the +5v pulse exiting a timed relay that activates my stater when a listed tag is read. The only problem is that in different situations the starter needs to be engaged for different amounts of time, i.e. cold morning / car still warm etc. 
Does anyone have suggestions as to how I can get this to behave more like a regular key ignition? Is there any way to set it so that when a known tag is polled the reader won't drop the voltage on the +5v pulse line until the tag has been removed from the reader's field? Maybe set it to poll the tag every 2ms or some such?

Any pointing in the right direction would be helpful, thanks!

Edited by AdmiralVorian - 23 August 2010 at 1:32pm

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AdmiralVorian Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 22 June 2010 Status: Offline Points: 18	Post Options Post Reply Quote AdmiralVorian Report Post Thanks(0) Quote Reply Topic: RedBee -automotive- Posted: 23 August 2010 at 12:06pm
	I am planning on using a redbee reader as my RFID solution to start me vehicle. My current wiring diagram has the +5v pulse exiting a timed relay that activates my stater when a listed tag is read. The only problem is that in different situations the starter needs to be engaged for different amounts of time, i.e. cold morning / car still warm etc. Does anyone have suggestions as to how I can get this to behave more like a regular key ignition? Is there any way to set it so that when a known tag is polled the reader won't drop the voltage on the +5v pulse line until the tag has been removed from the reader's field? Maybe set it to poll the tag every 2ms or some such? Any pointing in the right direction would be helpful, thanks! Edited by AdmiralVorian - 23 August 2010 at 1:32pm

ecnal Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Groupie Joined: 18 April 2009 Location: United States Status: Offline Points: 61	Post Options Post Reply Quote ecnal Report Post Thanks(0) Quote Reply Posted: 23 August 2010 at 2:27pm
	I'm not familiar with the RedBee reader, but if it puts out the +5v as long as the tag is in read range, wouldn't it just be holding your tag in range for however long it takes for the engine to turn over? Like if it needs to crank for five seconds, hold the tag in range for five seconds. If it needs one, hold it there for one.

amal Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Admin Group Joined: 22 November 2005 Location: United States Status: Offline Points: 2060	Post Options Post Reply Quote amal Report Post Thanks(0) Quote Reply Posted: 23 August 2010 at 3:50pm
	Typical solutions use a manual "start" push-button/relay combination where the RFID reader latches relays to act like the "on" function of the key, as well as enable the start push-button to function... then you can manually press the start button as long as you need to get the engine started.
	Amal ;) www.amal.net

AdmiralVorian Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 22 June 2010 Status: Offline Points: 18	Post Options Post Reply Quote AdmiralVorian Report Post Thanks(0) Quote Reply Posted: 25 August 2010 at 1:37pm
	amal - the situation you are describing is how I currently have it wired, i.e. the reader excites a timed relay that enables my pushbutton. what I want to try to setup is a situation like encal is describing, but I do not know if it is possible with the redbee, i might need to add an arduino / write code etc. Is there any way to configure the redbee to activate a pulse line when the tag comes in range and KEEP it activated until the tag goes out of range?

amal Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Admin Group Joined: 22 November 2005 Location: United States Status: Offline Points: 2060	Post Options Post Reply Quote amal Report Post Thanks(0) Quote Reply Posted: 25 August 2010 at 4:27pm
	To my knowledge there isn't a way to have the RedBee operate that way, however you might want to look into latched relays. They only require a pulse to get them latched, then they stay that way even if the pulse leaves. You can unlatch them by cutting power to them, or using a flipflop IC tied to the redbee output and a second, normally closed relay to act as a cutoff switch... then you scan the tag once and the car is ready to go/start... scan the tag again and the car shuts off as if you took the key out. Check the rather long motorcycle post for more info on latching relay setups for ignition systems. http://rfidtoys.net/forum/forum_posts.asp?TID=692&KW=motorcycle&PN=1&title=motorcycle-keyless-ignition
	Amal ;) www.amal.net

AdmiralVorian Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 22 June 2010 Status: Offline Points: 18	Post Options Post Reply Quote AdmiralVorian Report Post Thanks(0) Quote Reply Posted: 25 August 2010 at 4:55pm
	Yeah I'm worried that the redbee won't trip a 30A automotive relay. My plan now is to use a solid state relay to switch an automotive relay. do you know which ss relay I may need? Is there anything I should add to keep the redbee safe? Edited by AdmiralVorian - 25 August 2010 at 5:03pm

amal Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Admin Group Joined: 22 November 2005 Location: United States Status: Offline Points: 2060	Post Options Post Reply Quote amal Report Post Thanks(0) Quote Reply Posted: 25 August 2010 at 5:48pm
	You're right, the redbee will not trip that. It has a max 20ma output so you will have to use a transistor or a 5v reed relay from Radio Shack, and then use that to power the automotive relays. Look at some of the earlier, less sophisticated designs put up in the first couple pages of that thread and you'll see what I'm talking about. The reed relay and protection diode should be all you need, or you could use a switching transistor.
	Amal ;) www.amal.net

AdmiralVorian Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 22 June 2010 Status: Offline Points: 18	Post Options Post Reply Quote AdmiralVorian Report Post Thanks(0) Quote Reply Posted: 02 September 2010 at 12:11pm
	so I'm going to use 12v fused power on the barrel connector. can i carry the load for a reed relay and an LED on the reader or should I just have 5v power supply?

amal Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Admin Group Joined: 22 November 2005 Location: United States Status: Offline Points: 2060	Post Options Post Reply Quote amal Report Post Thanks(0) Quote Reply Posted: 02 September 2010 at 12:56pm
	I think you'd be better off to just power the LED from the switched leads of the relay, not the coil leads (the leads powered by the redbee).If the switched side of the relay is switching 12v, use a 1k ohm resistor in series with the LED and you'll be fine.
	Amal ;) www.amal.net

AdmiralVorian Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 22 June 2010 Status: Offline Points: 18	Post Options Post Reply Quote AdmiralVorian Report Post Thanks(0) Quote Reply Posted: 15 September 2010 at 8:59pm
	So I have this wired up per the third diagram on page three of the redbee manual. The only difference is that I am using a 12v source (for range) and I have a 5v voltage regulator powering the rest. When I initially power up the system, the relay is exited and the LED is on. I swipe a tag (the reader is set to go high for 5 seconds on OUT1) and wait five seconds. When the voltage drops, the LED and the relay both turn off. Subsequent tag reads produce the expected result. Edited by AdmiralVorian - 17 September 2010 at 12:50pm