RTT control block not found when using pylink

RE: RTT control block not found when using pylink

RichM — Wed, 17 Sep 2025 12:48:33 GMT

Wow, that's great. I guess the use of the if statement was misguided.

Thanks much, that will get me going.

Rich

RE: RTT control block not found when using pylink

Hakon — Wed, 17 Sep 2025 09:13:44 GMT

Seems like the issue was with the python script itself. I did some changes and now it works fine;

import pylink
import time
import sys

# The serial number of your J-Link probe. 
# This is useful if you have multiple J-Link devices connected.
# You can find the serial number using the 'pylink.jlink_list()' function or the J-Link Commander.
JLINK_SERIAL_NO = None # Or provide your serial number here


# Define the device name. For the Thingy:91's nRF9160 SiP, this is 'nRF9160_xxAA'.
TARGET_DEVICE = 'nRF9160_xxAA'

# Initialize and open a connection to the J-Link
try:
    jlink = pylink.JLink()
    # Open a connection to the J-Link. 
    # The serial number is optional but recommended for clarity.
    if JLINK_SERIAL_NO:
        print(f"Connecting to J-Link probe with serial number {JLINK_SERIAL_NO}...")
        jlink.open(serial_no=JLINK_SERIAL_NO)
    else:
        print("Connecting to the first available J-Link probe...")
        jlink.open()
    
    # Connect to the target device (Thingy:91's nRF9160)
    print(f"Connecting to target device: {TARGET_DEVICE}...")
    jlink.connect(TARGET_DEVICE, verbose=True)



    # Wait for RTT to be initialized by the target firmware
    print("Waiting for RTT control block...")
    time.sleep(2)  # Wait for a moment to let RTT initialize on the target

    # Search for and start the RTT control block
    jlink.rtt_start()
    print("RTT started. Reading RTT data. Press Ctrl+C to exit.")


    while True:
        # Read from RTT buffer 0. Timeout is in milliseconds.
        data = jlink.rtt_read(0, 1024)
        if data:
            # Decode and print the received data
            print(bytes(data).decode('utf-8'), end='')
        time.sleep(0.1)  # Poll every 100ms

except KeyboardInterrupt:
    print("User interrupted. Exiting.")
finally:
    jlink.close()

RE: RTT control block not found when using pylink

RichM — Mon, 15 Sep 2025 15:27:25 GMT

I've tried both 0 and 0x0000000020010100 (found in the map file) with the same results.

I am not certain what you mean by "Set the RTT control Block address to 0". Do you mean to do this in the python script?

I am also not clear by exactly what you mean by the "viewer/logger"

devzone.nordicsemi.com/.../modem_5F00_shell.zip devzone.nordicsemi.com/.../4213.Test100.py

RE: RTT control block not found when using pylink

Hakon — Mon, 15 Sep 2025 14:32:30 GMT

Hello,

can you try the advice here?

"The SEGGER Control Block cannot be found by automatic search by the RTT Viewer/Logger. As a workaround, set the RTT Control Block address to 0 and it will try to search from address 0 and upwards. If this does not work, look in the builddir/zephyr/zephyr.map file to find the address of the _SEGGER_RTT symbol in the map file and use that as input to the viewer/logger."

RE: RTT control block not found when using pylink

RichM — Fri, 12 Sep 2025 15:55:12 GMT

FYI, here is the RTT modem shell which seems to work very nicely and have plenty of good features.

devzone.nordicsemi.com/.../ModemShellRtt.hex