Understand the Problem Context
When addressing intermittent programming failures with Segger J-Link, the first step is to understand the exact circumstances under which these failures occur. This involves identifying if the failures are related to particular devices, specific times, or conditions such as power fluctuations or electromagnetic interference. Collect detailed logs from the J-Link tool to analyze error messages or fault codes, which can give clues about the root cause of the problem.
Update J-Link Software and Firmware
One of the most straightforward solutions that can resolve many intermittent issues is ensuring that both the J-Link software and the firmware are up-to-date. Segger frequently releases updates that contain bug fixes and improvements.
Download the latest J-Link Software and update the firmware as follows:
JLinkExe -autoconnect 1
Check Power Supply and Connections
Intermittent programming failures often result from unstable power or loose connections. Ensure that your target device is receiving stable power and securely connected. Consider using additional capacitors on the power line to smooth out fluctuations. If possible, use a dedicated power supply for your target device.
Review Configuration and Settings
Ensure that the J-Link configuration and settings are suitable for your target device. Mismatched settings such as incorrect interface type, using SWD instead of JTAG, or misconfigured clock speed can lead to failures.
Example configuration using JLinkExe:
Device = STM32F407VG
Interface = SWD
Speed = 4000
Examine Any Watchdog Timers
If your target device has a watchdog timer that is enabled, it could reset the device while programming. Consider disabling the watchdog timer during the programming process.
Sample code snippet to disable watchdog timer in firmware:
#include "stm32f4xx.h"
void Disable_Watchdog(void) {
IWDG->KR = 0x5555; // Disable write protection of IWDG
IWDG->PR = 0x0000; // Set prescaler
IWDG->RLR = 0x0FFF; // Set reload register
IWDG->KR = 0xAAAA; // Reset watchdog timer
}
Use Proper Debugging Techniques
Utilize the J-Link tool's logging feature to gather detailed information regarding the programming process. This can help identify irregularities or unexpected behaviors.
Enable logging by using:
JLinkExe -Log MyLogFile.log -autoconnect 1
Perform Test Run on a Different Device or Port
If possible, test the programming on a different target device or through another J-Link port to determine if the issue is specific to one setup. This can help identify if the problem is with a particular device or cable.
Consider Environmental Factors
Examine the working environment for potential sources of electromagnetic interference, vibration, or temperature extremes that could be affecting the programming process. These can introduce intermittent failures that are not easily traced back to hardware or software issues.
Consult Documentation and Support
Leverage official Segger documentation and support resources. Review technical manuals, FAQs, and engage with community forums to gather insights or solutions from those who have experienced similar problems.
By methodically addressing each of these potential factors, a firmware developer can effectively diagnose and solve intermittent programming failures with Segger J-Link, ensuring more reliable programming sessions.
