Page 1 of 1

2Km Transparent serial link test and implementation

Posted: Tue Oct 11, 2011 9:50 am
by dramida
I've put into practice the serial link between RX and TX with V1.10 firmware version of OpenLRS.
I made a few tests before working and i share my conclusion to make it easier for you:

The code for receiver should be configured like this:

Code: Select all

#define SERIAL_BAUD_RATE 115200 //115.200 baud serial port speed

//###### TELEMETRY MODES ########
#define TELEMETRY_ENABLED 1  // 1 = Enabled(bidirectional mode)  0 = Disabled(unidirectional mode)
#define TELEMETRY_MODE 0 // 0 = Transparent Bridge(750 byte/second max.) // 1 = Standard OpenLRS Telemetry

//#define Serial_RSSI //Serial RSSI value for analyzing



The code for transmitter should be configured like this:

Code: Select all

//###### SERIAL PORT SPEED #######
#define SERIAL_BAUD_RATE 115200 //115.200 baud serial port speed

//###### TELEMETRY MODES ########
#define TELEMETRY_ENABLED 1  // 1 = Enabled(bidirectional mode)  0 = Disabled(unidirectional mode)
#define TELEMETRY_MODE 0 // 0 = Transparent Bridge(750 byte/second max) // 1 = Standard OpenLRS Telemetry
#define TELEMETRY_OUTPUT_ENABLED 1 // 1 = Enabled  0 = Disabled  //Enables the Serial Telemetry Data Output. If you need only Buzzer alerts, disable it for less processing time.


To check the functionality, connect the computer to transmitter serial interface (Rx-to-Tx) and start HyperTerminal from Programs-Accessories-Communication. Then configure the link as follows: select the COM port, configure it to 115200 baud, 8 bits, parity none, stop bits 1 , software flow control.
Then go to receiver and make a loop (a wire) between RX and TX pin.

Now when you press a key in HyperTerminal, the character goes wireless to receiver and then receiver through loop wire send it back to transmitter and you will see it on the HT screen as an echo. If you disconnect the loop wire, the character you sent won't be visible as an echo anymore.

hint: Having a LED near you helps you find the TX witch lights the led. So connect the wire witch lights the led (TX) with the one who don't (RX), RX-to-TX. The longer pin of the led connects to positive/TX and shorter to ground.

GOOD LUCK!

Now i am working to implement the serial wireless communication between multicopter Multiwii board and GUI. I reached a dead end because the RX and TX of arduino mega board are hardware connected to embeded ftdi witch is driving the signals.
Please share your work here as i do.

Re: 2Km Transparent serial link test and implementation

Posted: Tue Oct 11, 2011 2:26 pm
by didlawowo69
really interesting,
it work with bluetooth, with wifi it's was interesting.

do you think it's possible to send command from remote gamepad controller (wifi), in serial mode ?

Re: 2Km Transparent serial link test and implementation

Posted: Tue Oct 11, 2011 5:32 pm
by dramida
Yes, you already can send rc comands from PC in serial mode with OpenLRS, as a three character word. More details on OLRS forum. With OpenLRS there is no need for PPM signal from transmitter, you could use only the computer.

Re: 2Km Transparent serial link test and implementation

Posted: Wed Oct 12, 2011 10:09 am
by dramida
Question:

What bitrate is between GUI and MWC ? (i know that the actually baudrate is 115200 but is not used at 100% in both directions)

How ca i measure the load of serial link?

The OLRS sistem supports 700Byte/sec download and 100Byte/sec upload (the rest of the band is used for RC link). Can it fit on MWC? How could i fit the MWC trafic on OLRS ?

Re: 2Km Transparent serial link test and implementation

Posted: Mon Oct 24, 2011 10:51 pm
by dramida
The high bitrate of MWC is incompatible with the low bitrate (750KBps)- high baud rate (115200) transmission requirements of OLRS v1.10.