Halt In Boot (Hib) - Texas Instruments SimpleLink CC2620 Technical Reference Manual

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5.6

Halt In Boot (HIB)

The CC26xx and CC13xx devices implement a mechanism to ensure that the external emulator can take
control of the device before it executes any application code. This mechanism is called halt in boot (HIB).
When HIB detects debug activity, the boot code stops in a wait for interrupt instruction (WFI) at the end of
its execution before jumping to the application code in Flash.
Detection of activities on the TCK pin (which powers up the JTAG power domain) is the condition for HIB
when next boot occurs. If JTAG power domain is turned off by entering the test logic reset (TLR) state
before a system reset occurs, the HIB conditions can be cleared. The HIB conditions are not cleared if
AON_WUC:SHUTDOWN.EN (see
written to 1.
To exit HIB, the external emulator must connect to the device and first HALT, then RESUME the CPU
through DAP. After resuming, the program execution continues from the application code.
5.7 Debug and Shutdown
The debugger cannot stay connected in shutdown mode because the power source for debug subsystem
turns off in this mode. This means that entering shutdown causes abrupt disconnection from the emulator.
To facilitate debugging of the shutdown scenarios, the CC26xx and CC13xx devices have the following
considerations:
• If a device is in shutdown mode, activity on TCK causes immediate wake up.
• If conditions for HIB are met while entering shutdown mode, the device wakes up as soon as it
reaches the shutdown state.
NOTE: If either of these considerations occur, the boot code (before handing control to the
application code) waits in a loop until an I/O wake-up event occurs.
SWCU117C – February 2015 – Revised September 2015
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Section 6.2.3.7, SHUTDOWN Register (Offset = 18h) [reset = X]) is
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Halt In Boot (HIB)
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JTAG Interface