microcontroller- Bluetooth module-physical connection

[Oana]

bluetooth module microcontroller

Hi,

I have a LMX9838 Bluetooth module from national semiconductors,I want to interface it with a microncontroller(PIC or Atmel, I don't know yet). The thing is how do I connect them, just connect the RXD, TXD of the two chips together? (that's what I am thinking)

Thank you!!

 

[rex_llama]

atmega bluetooth

Well, they suggest connecting the hardware flow control lines (CTS/RTS). But you can disable the hardware flow control with a command, and not connect those pins if you think that your microprocessor can keep up with the data from the LMX9838 or vice versa.

 

[gorkin]

bluetooth atmega

Pay attention in electrical characteristics between two side (uC and bluetooth module). In case of not compatibility, one level translator will be required! Check datasheet before build your spaghetti hardware ... and good work!

Gorkin

 

[Oana]

microcontroller bluetooth

Hei gorkin,

Yes, I have a problem there, because obviously i did read the datasheets of LMX9838 and ATmega16(this is the microcontroller that i was thinking of using) and LMX9838 has an 3.3V power supply and ATmega16 has an 5V power supply, so like you said I need some kind of level translator, do you know what kind?(like an MAX? ) I am not very experienced in this area and also a schematics would really help me

Thanks a lot!!!
Oana

 

[gorkin]

lmx9838 project

Hello!
Select your voltage translator in:
**broken link removed**

In your case, do you need 5V to 3.3V.
Sorry, but I cannot draw a schematic for you because now I am not have much time for expend! I am a student and I work too in a local small company in Brazil, so I am not have free-time...

If there are other question, post-it!

Gorkin

 

[dilan2005]

lmx9838 schematic

hi,
for initial testing following simple voltage divider can be used to convert ATMEGA 5V tx signal to 3.3v.

but i am not sure that atmega will take 3.3v from bluetooth chip as logic 1 (for microchip pics it's ok) .please go through the data sheet.

following cct will work but i strongly recommended to use a transceiver chip.specially when operating higher clock rate.

GOOD LUCK!

rgds
dilan

 

[Eugen_E]

bluetooth atmega interface

If you don't need the high clock rate of the ATmega16 (16MHz), you can use an ATmega16L, which works at max. 8MHz and 3.3V. This way you can eliminate the interface circuit.

If you are "forced" to use ATmega16 @ 5V, there are 2 ways:
- simple
On the Bluetooth_TX---->AVR_RX connection you don't need anything (AVR sees 3.3V as logic 1)
On the AVR_TX------>Bluetooth_RX connection use the voltage divider from dilan2005 post
For the usual UART speeds (<1Mbps), it's enough.

- using a 5V tolerant 3.3V circuit, like 74VHC08
**broken link removed**

 

[Oana]

bluetooth microcontroller

thanks everyone!!
it was really helpfull what you told me!
thanks again!
Oana

 

[acidhax]

connection between bluetooth and microcontroller

If You don't mind me asking, what method did you use for soldering this little puppy? Did you make a PCB or anything?

 

[yus]

atmega16 bluetooth

can I join on this thread?

this is how i solder the LMX9838 BT module for my project:

*no PCB

it's a bit risky, 'coz the pads of the module can easily peel off..
I'd accidentally damaged the previous module.

 

[yus]

bluetooth module atmega

.. using LMX9838 and pic16LF73

 

[vinod2211]

lmx9838 avr

so oana which translater did u use for the interfacing of atmega16 to the module(on rx tx lines)..or did the mega16 take 3.3v as the 1 (high)

 

[imtiyazmuc]

Re: Interfacing bluetooth to microcontroller and Bluetooth to PC

your PC connected USB dongle will detect the receiver UART module as soon as the receiver module is powered on

 

[rocky_singh3003]

I want to communicate between two atmega16s using this bluetooth device. Is it possible, and if it is, can anyone help me with the block diagram?
Thanks

 

[Keith22]

Re: atmega bluetooth

Hi Rex_llama
what pins would you connect the CTS and RTS of a BTM180 to what pins on a fujitsu microcontroller(SK-FR-144PMC-91467B)?