NRF_LOG print double precision float number

Question

I am on SDK15.3, NRF52840, armgcc, makefile, console 
 I need to print a double float number in format of "x.xxxxE-xx". I already know that NRF_LOG can only print float with MARKER, so I use sprintf to format the number into a string buffer first, and then I use NRF_LOG to print that string using "%s" format specifier. 
 char abuf[40];
 memset(abuf, 0, sizeof(abuf));

 uint8_t len = sprintf(abuf, "%.5E", 3000.8766);
 
 NRF_LOG_DEBUG("[KF] updated K gain: %s, %d
", abuf, len);

However I only get white spaces or unprintable character. 
 Anyway I can do this properly? 
 thank you. 
 
 /Roland

Jørgen Holmefjord · Accepted Answer

I do not see any ways that the logger backend could be causing this. However, one thing you should try is to use NRF_LOG_PUSH () to push the string to the internal string buffer if this is part of a larger application, and you are using deferred logging . The string may be overwritten on the stack before it is processed by the logger backends. It could look like this is the problem in your latest log message, since the length seems to be correct at 11.

NRF_LOG print double precision float number

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