Segger RTT - How to increase maximun line count?

RE: Segger RTT - How to increase maximun line count?

Lück — Fri, 23 Oct 2015 14:46:10 GMT

Thanks for your fast answers! I use SEGGER_RTT_printf(0, "%c\t%u\r\n", <uint8_t>, <uint32_t>); directly in the ISR which will be triggered 4x every 1ms. Sure, this is quite often but only few data are printed hence RTT should do the job within a few microseconds [us]. Seems that the printf overhead is quite large...

To solve this issue I will implement a large FIFO storing the received data during the test and after the test is stopped printing the whole FIFO content which is not time critical anymore.

RE: Segger RTT - How to increase maximun line count?

muhkuhns — Fri, 23 Oct 2015 12:26:02 GMT

Glad and sad to hear as well. I used SEGGER_RTT_printf(0, "\r\n%d;%d;%d;%d;%d;%d;%d;%d",d...) to output my measurements every 250ms. This worked fine and the SoC could perform as usual. Sadly I can't anymore on this topic. Good Luck!

RE: Segger RTT - How to increase maximun line count?

Lück — Fri, 23 Oct 2015 12:21:07 GMT

Thanks for the answer. The hint to start the RTT viewer and then use any Telnet client works fine to logg the data (I use putty: Host Name = localhost, Port = 19021). However RTT does not be as fast as claimed on the SEGGER webpage. With UART printf I still get the better performance! Actually I have no idea why RTT performs bad...

RE: Segger RTT - How to increase maximun line count?

Lück — Thu, 22 Oct 2015 17:02:49 GMT

@ muhkuhns: I cannot see any other answer or comment in this thread giving a solution. The solution I described works but the performance is even worse than with UART printf. I have up to four values to be logged every 1ms. With UART printf I miss approx. 55% and with RTT approx. 70%. Do you have experienced any performance issues like this?

RE: Segger RTT - How to increase maximun line count?

Lück — Thu, 22 Oct 2015 16:54:16 GMT

All right, I found a possibility:

download the Segger Software and Documentation pack
extract and install it (do not replace existing DLLs as it may conflict with an existing tool chain)
in the install folder (e.g. "C:\Program Files (x86)\SEGGER\JLink_V502f") find the JLinkRTTLogger.exe application and start it
enter the device name which is the Segger serial number of the device (maybe also any other name works?)
follow the instructions and enter the required parameters
select the device from the popup but do not update the device firmware (if asked)
in device selection prompt (if shown) press "Yes" and select your target device (in my case nRF51822_xxAA)

Now the logger started to log...

RE: Segger RTT - How to increase maximun line count?

muhkuhns — Thu, 22 Oct 2015 15:50:58 GMT

see my addes answer. btw: You should have posted this as the comment it is, and not as an answer.

RE: Segger RTT - How to increase maximun line count?

muhkuhns — Thu, 22 Oct 2015 15:50:49 GMT

Sorry I didn't answered this one by my own till now. As a work around I used telnet.

As far as I remember you don't have to do anything else one the rtt side after you have started the viewer as usual. Just install/enable telnet on your windows computer and you are good to.

Here is the script I wrote (.vbs) to automatically connect and log everything to a .txt file named with date+time:

set sh=WScript.CreateObject("WScript.Shell")
sh.run "Telnet"
WScript.Sleep 100
D = Date
T = Time
Timestamp = Year(D) & Right("0" & Month(D), 2) & Right("0" & Day(D), 2) & _
    "_" & _
    Right("0" & Hour(T), 2) & Right("0" & Minute(T), 2) & Right("0" & Second(T), 2)
sh.SendKeys "set logfile C:\Users\yourname\Dropbox\Messungen\" & Timestamp & "_Messreihe.txt"&vbcr
WScript.Sleep 500
sh.SendKeys "set logging"&vbcr
WScript.Sleep 500
sh.SendKeys "open localhost 19021"&vbcr
Wscript.Sleep 1000

RE: Segger RTT - How to increase maximun line count?

Lück — Thu, 22 Oct 2015 15:45:08 GMT

Hi muhkuhns. I have the same problem that I want to use RTT for data logging as UART printf() is too slow. In addition I need to log data from three devices connected to the PC at the same time. Therefore I would be verry interessted in your solution for that issue. Did you find a solution so far? Or does someone else know how to log data with RTT?

RE: Segger RTT - How to increase maximun line count?

muhkuhns — Tue, 02 Jun 2015 08:11:40 GMT

I registered at their forum but still waiting for any confirmation mail or similiar to be sent... can't post there.

RE: Segger RTT - How to increase maximun line count?

RK — Mon, 01 Jun 2015 15:45:45 GMT

Have you tried asking on Segger's forums? They provide the viewer after all.