RN42-APL dev board not authenticating when receiving transmit bytes

Question

I recently received the Microchip/Roving Networks RN42-APL development kit from Avnet, and I am able to get the sample iOS app to run and do loopback tests and everything is great (BT connects, authenticates, aware that app is on).

However, when I place this board in a real circuit, where data is flowing to the RX-In pins, the RN42 won't even authenticate!

Has anyone seen a functional example of this MFI chip? The whole 'it just works' isn't really ringing true. Is there something I need to -do- before this chip can send and receive data?

Answer 1

So I figured out the issue (I think). It was unrelated to the firmware, but it seems that the device wouldn't authenticate if there was traffic on the UART lines before authentication had happened.

I don't know whether where this limitation comes from, nor do I really care, but if anyone runs into this, I would try shutting off UART traffic until authentication.

Answer 2

what exactly do you mean that the RN-42-APL BT module doesn't authenticate? I used RN-42-APL + MFi 2.0c chip for iOS authentication and it works well. However the newest firmware 5.43 has still some bug related to authentication with Android system. Previously I used BT module with firmware 5.36. Engineer from Microchip told me, that previous firmware had some bugs related to authentication which requires PIN code. The newest firmware has been improved, but I found another one bug during my tests.

MFi chip must be connected with 2-wires to BT module. This chip uses I2C data transfer. I designed and constructed real device which was based on these components. Finally, this module works well with iOS, authentication mode you can change with SA,x command. Please read the manual. There are 4 options: 0, 1, 2 and 4.