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Topic: [SOLVED] Problem with Bluetooth HC-05 Interfacing for Fixture. (Read 157 times) previous topic - next topic

Rachman11

Nov 24, 2017, 04:57 am Last Edit: Dec 06, 2017, 02:46 am by Rachman11 Reason: close the issue
hello everyone,

I need a help and advise about HC-05 bluetooth interfacing for my project,

I want to make a fixture for wireless project using HC-05 Bluetooth,
the problem is the DUT is not response if send command from my Serial Com on PC,
Bluetooth connection is OK (Paired) HC-05 from PC (master) and HC-05 DUT (Slave).

my DUT S/W is Support for USB-RS232 Commnunication using ATEN, and my PC is already installed for each driver ( ATEN & USB to TLL CP2102 product ), so maybe the communication should be OK, but actually is not. my DUT is can not response.

my solution is a add Max 232 Module before connect to HC-05 (slave) in DUT Part.

actually i'm confuse about it ^^, the ATEN USB - UART is already have USB - UART converter, but why still need to add Max 232 module to make it communication is well.

(please see attachment for the concept )

question :
- is possible if not add max 232 module still can work ? or
  + if someone can tell me know about the problem, i'm really appreciate it.

- how to minimize part needed to make BT-HC05 Communication Fixture is can work as my concept ?
  + need advise or have a better/more simply design idea and share to me i'm very very appreciate it ^^.




thank you very much.

regard.

Grumpy_Mike

Quote
but why still need to add Max 232 module to make it communication is well.
Because RS232 signals are not the same as the TTL signals you need for the HC-05.

Basically an RS232 has -12V for a mark and +12V for a space, where as TTL has +5V for a mark and 0V for a space. So you need a converter to change the voltages and invert the signal.

Rachman11

Because RS232 signals are not the same as the TTL signals you need for the HC-05.

Basically an RS232 has -12V for a mark and +12V for a space, where as TTL has +5V for a mark and 0V for a space. So you need a converter to change the voltages and invert the signal.
thanks for explanation the Grumpy_Mike,
yes it's right, but in my case and i'm confuse about this :

- Part A ( Fixture side ) : DUT <-> ATEN (USB to TTL) <-> HC-05   = Communication is FAIL.

but in

- Part B ( PC side ) : PC <-> CP2102 (USB to TTL) <-> HC-05   = Communication is GOOD.


whereas, both of Part ( A & B ) is use identical USB to TTL Converter but in different result, CMIIW ^ ^.


actually i want to minimize of used part ( delete Max232 module in PART A), but not found yet solution about it.


Grumpy_Mike

Quote
Part A ( Fixture side ) : DUT <-> ATEN (USB to TTL) <-> HC-05   = Communication is FAIL.
Is this a new situation, one that is not covered in the diagram you posted?
Because a USB to TTL should be the same as a USB to RS232 + a RS232 to TTL

Unless of course their are some handshaking lines on the TTL connection that are not being asserted in the correct way to allow the DUT to send serial data.

Rachman11

Is this a new situation, one that is not covered in the diagram you posted?
Because a USB to TTL should be the same as a USB to RS232 + a RS232 to TTL
sorry for late reply Grumpy_Mike, there is no new situation, it's a same like i'm posted in the diagram.
below is the 2 condition with Fail and Good Condition in Part A ( Fixture side ) :
1. DUT <-> ATEN (USB to TTL) <-> HC-05                                  = Communication is FAIL.
2. DUT <-> ATEN (USB to TTL) <-> MAX232 module <-> HC-05   = Communication is GOOD.


if in Part A must need a max232 to make communication between DUT & HC05 is good,
so why in Part B no need max232, there is only use USB to TTL to make PC - HC05 communication is good.



Grumpy_Mike

As I said it is probably some handshake line on the TTL that has not been asserted.

Rachman11

As I said it is probably some handshake line on the TTL that has not been asserted.
thanks Grumpy_Mike,
now i'll close this issue.

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