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RSSI problems (Read 15963 times)
dwarfy
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RSSI problems
03/02/07 at 9:11am
 
Hello everybody !
 
I'm still trying to get the RSSI info for a received message.
 
Firstly, I updated the XBEE firmware to 10A2.
 
Secondly, I tried with the AT commands manualy in the console and it works.
 
Now I'm trying to have it via the 6th IO pin on the ARM microcontroler.
 
In order to do this , I added this to the utils.c file :
Code:
unsigned char P06_read() {
	return (unsigned char) ((IOPIN0 & 0x00000040) >> 6);
}
 


 
And I added this function to the main.c file:
Code:
//get RSSI from PWM output of xbee
int getRssi(void) {
	unsigned int i,j;
	int cnt = 0;

	//wait until 1 in P06
	do { i = P06_read(); }while(i==0);


	//for 64 s
	for (j=0;j<64;j++) {

		i <- P06_read();
		if(i != 0) { cnt++; }
		delayUs(1);
	}


	uart0SendChar(cnt);
	uart0SendChar("\n");
	return cnt;

}
 


 
I call this function after receiving a message on the robot.
And it sends the value '@' which means '64'
So it doesn't seems to work as it allways send the maximum value ?
 
As I sais I tried with the AT commands and it works ok but it is really too slow to wait 2 seconds each time I want the RSSI value.
 
About the OEM/API mode it seems a bit complicated as a good part of the firmware should be modified in order to pass from transparent mode to API mode.
 
Another thing I'd like to mention is that both the JAVA and PYTHON programs do not work right with the latest (10A2) xbee firmware.
 
Thank you in advance.
 
Mathieu
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Re: RSSI problems
Reply #1 - 03/02/07 at 9:24am
 
I tried 10A2 with the Java and Python console, and it seemed to work okay.  Make certain the baud rate on both modules gets set to 115k  - the X-CTU program seems to want to always set it at 9600.
 
I never managed to get the RSSI output to work, but don't know if that is because of 1090 firmware or because of some other problem.  There is a setting in the X-CTU setup in Diagnostic Commands for RSSI PWM Timer that you might try.  It probably would also be helpful to set up an oscilloscope to monitor the output of Pin 6 from the radio.
 
Hopefully it will not be necessary to use the API mode - you can see why I avoided it.
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« Last Edit: 03/02/07 at 9:27am by admin »  

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Re: RSSI problems
Reply #2 - 03/02/07 at 9:50am
 
Update -  I hooked up a scope, and RSSI Pin 6 is working with 1090, but you need to change RSSI PWM Timer to '1' - this sets a max duty cycle of 100 milliseconds.  The default value is 0x28 = 4 seconds !
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dwarfy
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Re: RSSI problems
Reply #3 - 03/02/07 at 10:29am
 
Thank you again for the help !
 
I'll try that on monday, because I'm home now and doesn't have HRV1 here.
 
About 10A2 I've set the baud rate to 115k on both radios !! so it's not the problem (well thinking about it I think the problem is in my modified firmware for hrv-1)
 
I'll check that on monday too.
 
Thank you again.
 
Mathieu
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Re: RSSI problems
Reply #4 - 02/24/08 at 2:35pm
 
I'm really new with this, and I'm trying to display the RSSI information on the Java console .  What would be the best way to achieve that?
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Re: RSSI problems
Reply #5 - 02/24/08 at 3:13pm
 
To start, you will have to add a command to the SRV-1 ARM7 firmware to measure the pulse width of the RSSI signal and send back a response.  Then in the Java code, you'll add a button in srv.config to send the RSSI query command, and you'll have to add some code to catch the response and display the number in some kind of Java widget.  So this isn't a simple project - you'll need to be able to modify the ARM7 firmware and do some GUI programming in Java.
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Re: RSSI problems
Reply #6 - 02/29/08 at 7:43am
 
RSSI is also something which is interesting. Is there a way to find the RSSI for a SRV1 With the blackfin?
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Re: RSSI problems
Reply #7 - 02/29/08 at 7:54am
 
Unfortunately, the Matchport does not expose the RSSI signal via a hardware pin, though  we have requested this feature.  It's only accessible by changing into console mode and querying some registers, but this is completely impractical in normal operation.
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Re: RSSI problems
Reply #8 - 02/29/08 at 9:30am
 
I'm guessing since there is an actual signal pin then uClinux may be able to report an RSSI value given the right program and Kernel config?
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Re: RSSI problems
Reply #9 - 02/29/08 at 9:33am
 
If such a pin existed, it would be possible to add support to a driver.  Unfortunately, there is no such pin on the Matchport.
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Re: RSSI problems
Reply #10 - 02/29/08 at 11:38am
 
Quote from admin on 03/02/07 at 9:50am:
Update - I hooked up a scope, and RSSI Pin 6 is working with 1090, but you need to change RSSI PWM Timer to '1' - this sets a max duty cycle of 100 milliseconds. The default value is 0x28 = 4 seconds !

 
I'm guessing that this RSSI pin 6 was not for the blackfin board... Sad
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Re: RSSI problems
Reply #11 - 02/29/08 at 11:42am
 
Correct - that was the original ARM7 controller with an XBee radio module.
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Re: RSSI problems
Reply #12 - 03/28/08 at 9:56am
 
Quote from admin on 03/02/07 at 9:50am:
Update - I hooked up a scope, and RSSI Pin 6 is working with 1090, but you need to change RSSI PWM Timer to '1' - this sets a max duty cycle of 100 milliseconds. The default value is 0x28 = 4 seconds !

 
I'm going to make some code for the ARM7 to show the RSSI info on the Java console (and hopefully from this I can display an estimate on how far away from the base it is). I don't have an o-scope, and I know the RSSI output returns a value from 0-100, so your saying that each millisecond it's on corresponds to a higher signal strength?
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Re: RSSI problems
Reply #13 - 03/28/08 at 10:52am
 
Right - if you set the RSSI register to 0x01 instead of 0x28, then I believe a pulse width of 100millisec would be equivalent to 100% signal strength
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Re: RSSI problems
Reply #14 - 03/28/08 at 11:52am
 
Has anyone else had trouble connecting to the Xbee radio using X-CTU? The manual says something about using a serial cable, but it's possible to use the USB radio, correct? I set the baud rate to 115200, no flow control, 8 data bits, no parity, and 1 stop bit. I turn on the ARM7 SRV, and when I press Test/Query, it says 'cannot open com port'. Any ideas?
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