eb500 failure to connect

nathan_app_dev

I am working with the EmbeddedBlue eb500 Bluetooth module on a parallax board of education. I was successful in establishing a connection between the transceiver and a cell phone once, but it quit working about 2 seconds after. Since then, my cell phone can not even find the eb500 when searching for Bluetooth devices. Does anyone have any suggestions. I've been using the following code to attempt the connections:

' {$STAMP BS2}

'Wait for the eb500 radio to be ready
PAUSE 1000
'Connect to the remote device
SEROUT 1,84,[noparse][[/noparse]"CON 00:12[noparse]:D[/noparse]1:58:F1:4F",CR]
SERIN 0,84,[noparse][[/noparse]WAIT("ACK",CR)]
'Wait for the connection to be established and switch to data mode
WaitForConnection:
IF IN5 = 0 THEN WaitForConnection
HIGH 6
PAUSE 300
'Wait for 20 seconds
PAUSE 20000
'Switch to Command Mode
LOW 6
SERIN 0,84,[noparse][[/noparse]WAIT(CR,">")]
'Disconnect from the remote device
SEROUT 1,84,[noparse][[/noparse]"dis",CR]
SERIN 0,84,[noparse][[/noparse]WAIT(CR,">")]

Any suggestions are appreciated. I restored the module to the factory settings already, but that did not change anything. Also, I cannot connect to the eb500 in hyperterminal, if this might affect the connection at all.

thank you for your help

-nathan

Bill Chennault

nathan--

I have some experience with the eb500 between a computer and a Stamp. But, are you trying to use the eb500 in that manner?

--Bill

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You are what you write.

nathan_app_dev

no- I'm trying to "connect" the eb500 with a cell phone. i say "connect" because I don't actually need to transfer data; i just need the eb500 to recognize that there is a signal, which to my understanding, it will send a '1' through pin 5 if it is connected (and the LED will turn on). But the problem is that I only successfully connected once on Friday. Since then, I cannot get the eb500 to do anything (as far as I can tell) other than get hot. I have two cell phones and neither of them can detect a signal from the eb500 when the program is running (although they did detect the signal earlier on Friday before my first and last connection). So I know that it was working, at least for the first few times I used it. I just hope the chip didn't fry because it always got quite hot every time I applied power to the board of education. Thank you for your assistance. As a senior in high school, I'm at the mercy of the trouble shooting forums and the sporadic emails that the a7 technical support randomly decide to respond to.

-nathan

Mike Green

1) You may not be able to connect with most cell phones. The EB500 only handles one Bluetooth protocol where a serial data channel is established. A lot of phones only provide for audio connections.

2) It's hard to tell what you mean by "hot". It can be normal for devices to get warm, but there's can be a big difference between warm and too hot to touch for more than a fraction of a second. It would be abnormal for the EB500 to get too hot to touch. You will have to post a diagram of exactly how you have things connected together. It's really impossible to give you more than very general advice without more (and detailed) information.

nathan_app_dev

On Friday (20 February), my cell phone was able to recognize the eb500 when I ran the above program and powered on the board of education. As you can see in the first diagram, the eb500 was added to my trusted list in the Bluetooth manager; this was a result of a single connection that terminated after about 2 seconds. Since then, the second diagram shows the following error message: the phone cannot detect a Bluetooth signal to connect to. The circuit I devised on the board of education isn't entirely important at the moment; as of now, I just need my cell phone to connect to the eb500 as it did the first time. Many thanks

-nathan

nathan_app_dev

The eb500 I was working with was defective; this was confirmed by testing the voltage across several key points on the circuit. But thanks for the assistance.

Chris Savage

Based on your pictures it appears the EB500 may not have been defective…I see you’re powering the BOE using a Wall Adapter. These can output voltages in excess of 12V which is the maximum allowed input voltage for the EB500. The EB500 is designed for use on the BOE-Bot in particular which normally uses batteries. You could damage a new EB500 by powering it from the BOE while using the wall adapter as in your picture if the voltage at V_IN is > 12VDC.

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Chris Savage
Parallax Engineering