half-duplex only with BlueSmirf Serial Radio

Wireless & IoT
1

Hi all, hope you can help me with this.

I just received a BlueSmirf serial radio from SparkFun.

Got it out of the bag, Connected to 5V, bridged RTC and CTS.

Connection to the BT dongle went efforlessly. New BT device recognized

offering Serial Port Service as COM3, etc.

I opened HyperTerminal, connected to COM3, 9600 8-N-1. The red led

in the BlueSmirf lights up indicating that a connection has been established.

I typed +++ and got my OK. I could type commands, got my firmware version

(BTW it is 2.8.1.4.0, slightly different from the BlueRadios docs that I have,

that refer to ver 2.8.1.0.0, could that be a problem?)

Anyway, everything seems OK, I typed ATMD to go back to passing data.

Connected the TX pin of the MCU (PIC) to the RX-I pin of the Bluetooth

unit, and a stream of ‘U’ appeared on my Hyperterminal screen. Great!

However, when I try to transmit from PC to MCU, it doesnt work, nothing

is received on the PIC. I checked the TX-O pin of the BT module with

the scope and it is always at a high level (5V). No sign of anything

coming through.

So the BT connection seems to be fine, works like a charm in command

mode, but in data mode only works in one direction.

I would have thought that the default setting in the unit would allow full-duplex communication.

Is there any aditional command that I should send to gain full-duplex ?

Does this look like a soft/conf problem or could this be a faulty unit?

Regards,

Antonio

2

The same thing happens to me. My firmware version is 3.4.1.2.0.

I don’t know if it’s a defect or if it needs some settings.

UPDATE: It is a timing and connection issue. If I check Reception errors and clear correctly reset the PIC RX the unit works with PIC:

… after rcv:

btfsc RCSTA,OERR ;if overrun error occurred

goto ErrSerialOverr ; then go handle error

return

ErrSerialOverr:

bcf RCSTA,CREN ;reset the receiver logic

bsf RCSTA,CREN ;enable reception again

return