Thread: TX/RX Beacon UART

Hi,

im currently working on a project where a TX sends a packet, the packet is picked up by the RX and the RX echoes back another packet. The echoed packet is picked up by the TX, and the signal strength and echoed packet is then sent through UART to a Single board computer as a string.

As the signal strength is inconsistent, i am trying to get the average of 3 of the same packets before sending the information through the UART. I am really new to C programming and I hope yall can help!

this is part of my code: (rssi is the signal strength)

insert

Code:

 /* Check the packet against what was transmitted */
        int16_t status = memcmp(returnCheck, rxPacket, checkLength);






        if(status == 0)
        {
            /* Toggle LED1, clear LED2 to indicate RX */
            PIN_setOutputValue(ledPinHandle, Board_PIN_LED1,
                               !PIN_getOutputValue(Board_PIN_LED1));
            PIN_setOutputValue(ledPinHandle, Board_PIN_LED2, 0);


            char buff[20];  // take a chance that 10 is always enough
            sprintf(buff,"%s %d",rxPacket,RSSIout);
            UART_write(uart, buff, strlen(buff));




        }

You could use error detection and error connecttion algorithms if you have issues with the signal:

Error Detection
Error Correction
Reed Solomon Codes
Error Correction & International Book Codes

So just to clarify, you want a function that returns the average value of the last 3 readings?

That's easy enough to achieve

I suggest that you give it a go and post what you have come up with if you have any problems

To get you started, have a look at this tutorial

Functions in C - Cprogramming.com

thank you all for the advice!

Hi salem nice to hear from you again! came to this forum as it was for C.

This is what i want to do:
Throw away all the samples, get three more and then output another average.

But my problem arrises as i may have multiple RX packets coming in with different RSSI values.

Originally Posted by Salem

So why did you jump forum?
Texas Instrument CC1350 UART for RSSI si - C++ Forum

Let's say your RSSI is an int, since you format it as one.

So you want an average of three.

Code:

int rawRSSI[3];
int numSamples = 0;

So your first step is

Code:

rawRSSI[numSamples++] = receivedRSSI;   // you didn't show how this arrives.

You then say

Code:

if ( numSamples == 3 ) {
    int avgRSSI = ( rawRSSI[0] + rawRSSI[1] + rawRSSI[2] ) / 3;
    char buff[20];  // take a chance that 10 is always enough
    sprintf(buff,"%s %d",rxPacket,avgRSSI);
    UART_write(uart, buff, strlen(buff));
}

What do you want to happen next?
- Throw away all the samples, get three more and then output another average.
- Throw away the oldest sample, get one more sample, and output a moving average.

Thank you all for the constructive input!

Hi salem good to hear from you again!
i came to this forum as it was C specific.

I want to do this:
Throw away all the samples, get three more and then output another average.

But the issue i face now is that i have multiple RXs that send Multiple RX packets to the TX with different RSSI values.

I am actually using the RSSI value to measure distance! and so far it has proven quite accurate!
My objective is to send the RX packet and the distance to the RX

Hi didnt want to start a new thread and i was hoping any of yall could help!

the code:

Code:

if ( numSamples == 3 ) {    int avgRSSI = ( rawRSSI[0] + rawRSSI[1] + rawRSSI[2] ) / 3;
    char buff[20];  // take a chance that 10 is always enough
    sprintf(buff,"%s %d",rxPacket,avgRSSI);
    UART_write(uart, buff, strlen(buff));
}

Works great but now i have an issue. I want to flush all the results out if i dont receive 3 signals within 5 seconds.
So after 5 seconds lets say i only receive two rawRSSI, i want to flush the current two rawRSSI and restart the process

sorry im not to familiar with what kind of clock is on my board but i am using a Texas Instrument CC1350 launchpad

Its just a bare board running my code! my board is connected to a single board computer

My apologies for the vague posts, still pretty new to the forums. But thanks for all the help so far Salem, much of my project has to be credited to you.

http://www.ti.com/lit/ug/swcu117h/swcu117h.pdf - this is the technical manual for the board i am using. I have previously read up on the timer function (page 1188) but i have failed to implement it in my system.

http://dev.ti.com/tirex/content/simp...26_x_x_8h.html - this is an example provided by the manufacturer of the board