ECC

ECC stands for error-correcting code. Memory chips use ECC to detect and correct bit errors, which can be caused by production (e.g., faults or aging). It is used with non-volatile flash memory as well as volatile RAM memory.

ECC works by generating and storing an ECC code in a memory-write process, and verifying code on a memory-read. Due to this process, ECC memory can be read only after it is written.

Handling ECC with flash memory

With ECC flash memory, J-Link software must be set up to prevent memory reading from taking place before writing. This can be done by executing multiple J-Link command strings.

The following snippet of J-Link script code will set up necessary options for ECC protected flash memory:

void ConfigTargetSettings(void) {
  JLINK_ExecCommand("SetCompareMode=0");                // Make sure that J-Link SW does not try to compare before programming
  JLINK_ExecCommand("SetFlashDLNoRMWThreshold=0");      // Make sure that the J-Link SW does not perform a read-modify-write
  JLINK_ExecCommand("SetDisableSkipBlankDataOnProg=1"); // Make sure that areas filled with blank data are also programmed by J-Link SW
  JLINK_ExecCommand("DisableFlashBPs");                 // Because of enabled interrupts and RAM is used for flash programming, we cannot allow flash breakpoints
  return 0;
}

For detailed information about J-Link command strings, refer to the J-Link Command Strings article

ECC Handling with RAM

ECC RAM is not readable after a reset, due to missing ECC code. J-Link software offers a convenient method for initializing a device's work RAM during connection in order to allow initial read access. While the work-RAM area is specified with device information within the J-Link software, it is adjustable via the J-Link command string 'SetWorkRAM'.

The following snippet of J-Link script code will initialize the work RAM:

void ConfigTargetSettings(void) {
  JLINK_ExecCommand("SetInitWorkRAMOnConnect = 1"); // Work RAM will be initialized on connect
  return 0;

For detailed information regarding SetInitWorkRAMOnConnect refer to the J-Link Command Strings article.