RTT stopped working in SES in SDK15.3

I ran into an issue using RTT on recent SDKs: In SDK15.3 and up RTT stopped working in Segger Embedded Studio. Here's what I found in case others are having the same issue:

Steps to reproduce:

  • Load “.../examples/ble_peripheral/ble_app_hrs/pca10040/s132/ses/ble_app_hrs_pca10040_s132.emProject
  • Change sdk_config.h to “#define NRF_LOG_BACKEND_RTT_ENABLED 1”

 This was tested on SDK15.3, SDK16, SDK17 on a PCA10040 dev-kit.

Host OSes tested on: 

  • macOS Mojave 10.14.6
  • CentOS 7

I tracked it down to the option "NRF_FPRINTF_FLAG_AUTOMATIC_CR_ON_LF" which is enabled by default. If that is set to 0, there are no issues.