Reset Sequence

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The reset sequence is device-specific. To reset most devices, ULINK2 asserts the JTAG RESET signal (pin 15 on the ARM 20-pin; pin 10 on the ARM 10-pin; pin 8 on the OCDS and ST JTAG Interface), then attempts to immediately stop the device.

Some ARM devices do not support an immediate stop after a reset and instruction execution happens before ULINK2 can issue a stop command. For these devices, when ULINK2 gets control, it stops the CPU, and then sets the MCU's program counter (PC) and stack register (CSPR) to simulate an immediate stop after reset.

Side-Effects for ARM Devices

Resetting an ARM device may generate unexpected side-effects. The following Knowledgebase Articles describe these side effects in more detail:

• ULINK: RESET BEHAVIOUR
• ULINK: SINGLE STEP AT RESET APPEARS TO FAIL
• ULINK: ARM DEVICE DOES NOT REACT
• ULINK: RECOVER STR71X WHEN JTAG DISABLE