Use J-Link Commander to Run DCI Command#

J-Link Commander from Segger is a command line-based utility that supports simple commands to verify and communicate with the target connection. There are two ways to run the DCI command through the J-Link Commander.

  1. J-Link Command File (*.jlink)

  2. J-Link Script File (*.JLinkScript)

This application note uses J-Link Commander v7.66g. The J-Link Commander's command line interface is invoked by JLink.exe located in C:\Program Files\SEGGER\JLink_V766g (Windows).

J-Link Command File#

The J-Link Command file below is an example to invoke the J-Link Commander in batch processing mode for the Erase Device operation. The delay (sleep 500) in milliseconds after writing the command word is device dependent. It may be shorter or longer.

connect
swdwritedp 2 0x01000000 ; Select DCI AP
swdwriteap 1 0x1008 ; DCI STATUS
swdreadap 3 
swdreaddp 3 ; Poll till DCI_STATUS.WPENDING (bit 0) is low
swdwriteap 1 0x1000 ; DCI WDATA
swdwriteap 3 0x08 ; Command word 0
sleep 500 ; Delay if necessary
swdwriteap 1 0x1008 ; DCI STATUS
swdreadap 3 
swdreaddp 3 ; Poll till DCI_STATUS.WPENDING (bit 0) is low
swdwriteap 1 0x1000 ; DCI WDATA
swdwriteap 3 0x430F0000 ; command word 1 (Erase Device)
sleep 500 ; Delay if necessary
swdwriteap 1 0x1008 ; DCI STATUS
swdreadap 3 
swdreaddp 3 ; Poll till DCI_STATUS.RDATAVALID (bit 8) is high
swdwriteap 1 0x1004 ; DCI RDATA
swdreadap 3 ; First word
swdreaddp 3 ; Status code is upper 16 bits, total length is lower 16 bits
exit

The example below is to run the J-Link Command file (assume EraseDevice.jlink is in the J-Link Commander folder) via the Windows DOS command prompt. The target device is EFR32MG21A, and the target interface is 1000 kHz SWD. The SWD speed is hardware dependent; for example, the length of the wires between the programmer and the device debug pins. The speed (frequency) can be higher for shorter wires and lower for longer wires.

JLink.exe -device EFR32MG21AXXXF1024 -if SWD -speed 1000 -CommandFile EraseDevice.jlink
SEGGER J-Link Commander V7.66g (Compiled Jul 7 2022 10:44:29)
DLL version V7.66g, compiled Jul 7 2022 10:42:43
J-Link Command File read successfully.
Processing script file...
J-Link>connect
J-Link connection not established yet but required for command.
Connecting to J-Link via USB...O.K.
Firmware: Silicon Labs J-Link Pro OB compiled Sep 16 2020 17:10:58
Hardware version: V4.00
S/N: 440048205
License(s): RDI, FlashBP
IP-Addr: DHCP (no addr. received yet)
VTref=3.326V
Device "EFR32MG21AXXXF1024" selected.
Connecting to target via SWD
Found SW-DP with ID 0x6BA02477
DPv0 detected
CoreSight SoC-400 or earlier
Scanning AP map to find all available APs
AP[3]: Stopped AP scan as end of AP map has been reached
AP[0]: AHB-AP (IDR: 0x84770001)
AP[1]: APB-AP (IDR: 0x54770002)
AP[2]: AHB-AP (IDR: 0x84770001)
Iterating through AP map to find AHB-AP to use
AP[0]: Core found
AP[0]: AHB-AP ROM base: 0xE00FE000
CPUID register: 0x410FD213. Implementer code: 0x41 (ARM)
Feature set: Mainline
Found Cortex-M33 r0p3, Little endian.
FPUnit: 8 code (BP) slots and 0 literal slots
Security extension: implemented
Secure debug: enabled
CoreSight components:
ROMTbl[0] @ E00FE000
[0][0]: E00FF000 CID B105100D PID 000BB4C9 ROM Table
ROMTbl[1] @ E00FF000
[1][0]: E000E000 CID B105900D PID 000BBD21 DEVARCH 47702A04 DEVTYPE 00 Cortex-M33
[1][1]: E0001000 CID B105900D PID 000BBD21 DEVARCH 47701A02 DEVTYPE 00 DWT
[1][2]: E0002000 CID B105900D PID 000BBD21 DEVARCH 47701A03 DEVTYPE 00 FPB
[1][3]: E0000000 CID B105900D PID 000BBD21 DEVARCH 47701A01 DEVTYPE 43 ITM
[1][5]: E0041000 CID B105900D PID 002BBD21 DEVARCH 47724A13 DEVTYPE 13 ETM
[1][6]: E0042000 CID B105900D PID 000BBD21 DEVARCH 47701A14 DEVTYPE 14 CSS600-CTI
[0][1]: E0040000 CID B105900D PID 000BBD21 DEVARCH 00000000 DEVTYPE 11 Cortex-M33
[0][2]: E00FD000 CID B105F00D PID 001BB101 TSG
Cortex-M33 identified.
J-Link>swdwritedp 2 0x01000000 ; Select DCI AP
Write DP register 2 = 0x01000000
J-Link>swdwriteap 1 0x1008 ; DCI STATUS
Write AP register 1 = 0x00001008
J-Link>swdreadap 3
Read AP register 3 = 0x000000B1
J-Link>swdreaddp 3 ; Poll till DCI_STATUS.WPENDING (bit 0) is low
Read DP register 3 = 0x00000000
J-Link>swdwriteap 1 0x1000 ; DCI WDATA
Write AP register 1 = 0x00001000
J-Link>swdwriteap 3 0x08 ; Command word 0
Write AP register 3 = 0x00000008
J-Link>sleep 500 ; Delay if necessary
Sleep(500)
J-Link>swdwriteap 1 0x1008 ; DCI STATUS
Write AP register 1 = 0x00001008
J-Link>swdreadap 3
Read AP register 3 = 0x00000000
J-Link>swdreaddp 3 ; Poll till DCI_STATUS.WPENDING (bit 0) is low
Read DP register 3 = 0x00000000
J-Link>swdwriteap 1 0x1000 ; DCI WDATA
Write AP register 1 = 0x00001000
J-Link>swdwriteap 3 0x430F0000 ; command word 1 (Erase Device)
Write AP register 3 = 0x430F0000
J-Link>sleep 500 ; Delay if necessary
Sleep(500)
J-Link>swdwriteap 1 0x1008 ; DCI STATUS
Write AP register 1 = 0x00001008
J-Link>swdreadap 3
Read AP register 3 = 0x00000000
J-Link>swdreaddp 3 ; Poll till DCI_STATUS.RDATAVALID (bit 8) is high
Read DP register 3 = 0x00000100
J-Link>swdwriteap 1 0x1004 ; DCI RDATA
Write AP register 1 = 0x00001004
J-Link>swdreadap 3 ; First word
Read AP register 3 = 0x00000100
J-Link>swdreaddp 3 ; Status code is upper 16 bits, total length is lower 16 bits
Read DP register 3 = 0x00000004
J-Link>exit
Script processing completed.

J-Link Script File#

The J-Link Script file below is an example to customize some actions performed by the J-Link Commander for the Read Serial Number operation.

// Function to select DCI AP register bank 0
int SelectDciAp(void)
{
 int stat;
 int value;
 JLINK_SYS_Report("- Select DCI AP register bank 0\n");
 value = 0x01000000; 
 stat = JLINK_CORESIGHT_WriteDP(2, value);
 if (stat < 0) {
 JLINK_SYS_Report1("- DP 2 write failed: ", value);
 }
 return stat;
}
// Function to write command to DCI_WDATA (0x1000) 
int WriteCommandWord(int command)
{
 int stat;
 int value;
 // Poll DCI_STATUS (0x1008) WPENDING bit (bit 0)
 do {
 value = 0x00001008;
 stat = JLINK_CORESIGHT_WriteAP(1, value);
 if (stat < 0) {
 JLINK_SYS_Report1("- AP 1 write failed: ", value);
 return stat;
 }
 JLINK_CORESIGHT_ReadAP(3);
 value = JLINK_CORESIGHT_ReadDP(3);
 if (value == -1) {
 JLINK_SYS_Report("- DP 3 read failed");
 return value;
 }
 if ((value & 0x0100) != 0) {
 JLINK_SYS_Report("- RDATAVALID is high, command aborted");
 return -1;
 } 
 } while ((value & 0x01) != 0);
 
 // Write command
 value = 0x00001000;
 stat = JLINK_CORESIGHT_WriteAP(1, value);
 if (stat < 0) {
 JLINK_SYS_Report1("- AP 1 write failed: ", value);
 return stat;
 }
 value = command;
 stat = JLINK_CORESIGHT_WriteAP(3, value);
 if (stat < 0) {
 JLINK_SYS_Report1("- AP 3 write failed: ", value);
 return stat;
 }
 JLINK_SYS_Report1("- Write command word ", command); 
 return stat;
}
// Function to read response from DCI_RDATA (0x1004)
int ReadResponse(void)
{
 int stat;
 int value;
 int count;
// Poll DCI_STATUS (0x1008) RDATAVALID bit (bit 8) 
 do {
 value = 0x00001008;
 stat = JLINK_CORESIGHT_WriteAP(1, value);
 if (stat < 0) {
 JLINK_SYS_Report1("- AP 1 write failed: ", value);
 return stat;
 }
 JLINK_CORESIGHT_ReadAP(3);
 value = JLINK_CORESIGHT_ReadDP(3);
 if (value == -1) {
 JLINK_SYS_Report("- DP 3 read failed");
 return value;
 }
 } while ((value & 0x0100) != 0x0100);
 
 // Read first 32-bit response word 
 value = 0x00001004;
 stat = JLINK_CORESIGHT_WriteAP(1, value);
 if (stat < 0) {
 JLINK_SYS_Report1("- AP 1 write failed: ", value);
 return stat;
 }
 JLINK_CORESIGHT_ReadAP(3);
 value = JLINK_CORESIGHT_ReadDP(3);
 if (value == -1) {
 JLINK_SYS_Report("- DP 3 read failed");
 return value;
 }
 // Get response count
 count = value & 0x00FF; 
 count = count >> 2;
 JLINK_SYS_Report1("- Number of 32-bit response word: ", count);
 // Get response code
 JLINK_SYS_Report1("- Response: ", value);
 stat = value >>16; 
 if (stat != 0) {
 JLINK_SYS_Report1("- Command error: ", stat);
 return -1;
 }
 
 // Read following 32-bit response word
 count = count - 1;
 while (count != 0) {
 // Poll DCI_STATUS (0x1008) RDATAVALID bit (bit 8) 
 do {
 value = 0x00001008;
 stat = JLINK_CORESIGHT_WriteAP(1, value);
 if (stat < 0) {
 JLINK_SYS_Report1("- AP 1 write failed: ", value);
 return stat;
 }
 JLINK_CORESIGHT_ReadAP(3);
 value = JLINK_CORESIGHT_ReadDP(3);
 if (value == -1) {
 JLINK_SYS_Report("- DP 3 read failed");
 return value;
 }
 } while ((value & 0x0100) != 0x0100);
 
 // Read 32-bit response word 
 value = 0x00001004;
 stat = JLINK_CORESIGHT_WriteAP(1, value);
 if (stat < 0) {
 JLINK_SYS_Report1("- AP 1 write failed: ", value);
 return stat;
  }
 JLINK_CORESIGHT_ReadAP(3);
 value = JLINK_CORESIGHT_ReadDP(3);
 if (value == -1) {
 JLINK_SYS_Report("- DP 3 read failed");
 return value;
 }
 JLINK_SYS_Report1("- Response: ", value);
 count = count - 1;
 }
 return 0;
}
// Function to connect DCI
int ConnectDci(void)
{ 
 int stat;
 int value;
 
 JLINK_SYS_Report("\n******************************************************");
 JLINK_SYS_Report("Connect to Series 2 Device DCI\n");
 JLINK_SYS_Report("- Select SWD by sending SWD switching sequence\n");
 stat = JLINK_CORESIGHT_Configure(""); 
 if (stat < 0) {
 JLINK_SYS_Report("- SWD connection failed");
 return stat;
 }
 // Manually select debug interface 
 JLINK_SYS_Report("- Clear sticky error flags\n");
 value = 0x0000001E; 
 stat = JLINK_CORESIGHT_WriteDP(0, value); 
 if (stat < 0) {
 JLINK_SYS_Report1("- DP 0 write failed: ", value);
 return stat;
 }
 JLINK_SYS_Report("- Power up system and debug\n");
 value = 0x50000000; 
 stat = JLINK_CORESIGHT_WriteDP(1, value); 
 if (stat < 0) {
 JLINK_SYS_Report1("- DP 1 write failed: ", value);
 return stat;
 }
 
 value = JLINK_CORESIGHT_ReadDP(0); 
 if (value != 0x6BA02477) {
 JLINK_SYS_Report1("- The connected device does not have a Secure Element (ID Code): ", value);
 return -1;
 }
 JLINK_SYS_Report1("- Read SWD-DP ID code: ", value);
 JLINK_SYS_Report("- Select DCI AP register bank 0\n");
 value = 0x01000000; 
 stat = JLINK_CORESIGHT_WriteDP(2, value); 
 if (stat < 0) {
 JLINK_SYS_Report1("- DP 2 write failed: ", value);
 return stat;
 }
 
 JLINK_SYS_Report("- Set up AP defaults\n");
 value = 0x22000002; 
 stat = JLINK_CORESIGHT_WriteAP(0, value); 
 if (stat < 0) {
 JLINK_SYS_Report1("- AP 0 write failed: ", value); 
 return stat;
 }
 JLINK_SYS_Report("Connect to Series 2 Device DCI OK\n");
 JLINK_SYS_Report("******************************************************");
 return 0;
}
// Function to run DCI command
void RunDciCommand(void)
{
 JLINK_SYS_Report("\n******************************************************");
 JLINK_SYS_Report("Read Serial Number\n");
 if (SelectDciAp() == -1) {
 JLINK_SYS_Report("- Select DCI AP failed\n");
 JLINK_SYS_Report("******************************************************\n\n");
 return;
 }
 if (WriteCommandWord(0x00000008) == -1) {
 JLINK_SYS_Report("- Write DCI command (length) failed\n");
 JLINK_SYS_Report("******************************************************\n\n");
 return;
 }
 if (WriteCommandWord(0xFE000000) == -1) {
 JLINK_SYS_Report("- Write DCI command (ID) failed\n");
 JLINK_SYS_Report("******************************************************\n\n");
 return;
 }
 if (ReadResponse() == -1) {
 JLINK_SYS_Report("- Read DCI command response failed\n");
 JLINK_SYS_Report("******************************************************\n\n");
 return;
 }
 JLINK_SYS_Report("Read Serial Number Done\n");
 JLINK_SYS_Report("******************************************************\n\n");
}
// Replace ConfigTargetSettings() in J-Link DLL
void ConfigTargetSettings(void)
{
 if (ConnectDci() == -1) {
 JLINK_SYS_Report("- Connect to DCI failed\n");
 JLINK_SYS_Report("******************************************************\n\n");
 return;
 }
 RunDciCommand();
}

The example below is to run the J-Link Script file (assume ReadSerialNo.JLinkScript is in the J-Link Commander folder) via the Windows DOS command prompt. The target device is EFR32MG21A, and the target interface is 1000 kHz SWD. The SWD speed is hardware dependent; for example, the length of the wires between the programmer and the device debug pins. It can be higher for shorter wires and lower for longer wires.

JLink -device EFR32MG21AXXXF1024 -if SWD -speed 1000 -autoConnect 1 -JLinkScriptFile ReadSerialNo.JlinkScript

SEGGER J-Link Commander V7.66g (Compiled Jul 7 2022 10:44:29)
DLL version V7.66g, compiled Jul 7 2022 10:42:43
Connecting to J-Link via USB...O.K.
Firmware: Silicon Labs J-Link Pro OB compiled Sep 16 2020 17:10:58
Hardware version: V4.00
S/N: 440048205
License(s): RDI, FlashBP
IP-Addr: DHCP (no addr. received yet)
VTref=3.328V
Device "EFR32MG21AXXXF1024" selected.
Connecting to target via SWD
ConfigTargetSettings() start
******************************************************
Connect to Series 2 Device DCI
- Select SWD by sending SWD switching sequence
- Clear sticky error flags
- Power up system and debug
- Read SWD-DP ID code: 0x6BA02477
- Select DCI AP register bank 0
- Set up AP defaults
Connect to Series 2 Device DCI OK
******************************************************
******************************************************
Read Serial Number
- Select DCI AP register bank 0
- Write command word 0x00000008
- Write command word 0xFE000000
- Number of 32-bit response word: 0x00000005
- Response: 0x00000014
- Response: 0x00000000
- Response: 0x00000000
- Response: 0xFF818E58
- Response: 0xE53470FE
Read Serial Number Done
******************************************************
ConfigTargetSettings() end