EM359X Datasheet, PDF (35/59 Pages) Silicon Laboratories – High-Performance, Integrated ZigBee/802.15.4 System-on-Chip Family

EM359x
4.7.5. Flash Patch and Breakpoint (FPB)
The EM359x integrates the standard ARM^® Flash Patch and Breakpoint (FPB). The FPB implements hardware
breakpoints. The FPB also provides support for remapping of specific instruction or literal locations from flash
memory to an address in RAM memory. The FPB contains:
Two literal comparators for matching against literal loads from flash space, and remapping to a
corresponding RAM space.
Six instruction comparators for matching against instruction fetches from flash space, and remapping to a
corresponding RAM space. Alternatively, the comparators can be individually configured to return a
breakpoint instruction to the processor core on a match, implementing hardware breakpoint capability.
Refer to chapter 16 in the Ember EM359x Reference Manual for more information.
4.7.6. Serial Wire and JTAG (SWJ) Interface
The EM359x includes a standard Serial Wire and JTAG (SWJ) Interface. The SWJ is the primary debug and
programming interface of the EM359x. The SWJ gives debug tools access to the internal buses of the EM359x,
and allows for non-intrusive memory and register access as well as CPU halt-step style debugging. Therefore, any
design implementing the EM359x should make the SWJ signals readily available.
Serial Wire is an ARM^® standard, bi-directional, two-wire protocol designed to replace JTAG, and provides all the
normal JTAG debug and test functionality. JTAG is a standard five-wire protocol providing debug and test
functionality. In addition, the two Serial Wire signals (SWDIO and SWCLK) are overlaid on two of the JTAG signals
(JTMS and JTCK). This keeps the design compact and allows debug tools to switch between Serial Wire and JTAG
as needed, without changing pin connections.
While Serial Wire and JTAG offer the same debug and test functionality, Silicon Labs recommends Serial Wire.
Serial Wire uses only two pins instead of five, and offers a simple communication protocol, high performance data
rates, low power, built-in error detection, and protection from glitches.
The SWJ pins are forced functions, and their corresponding GPIO_PxCFGH/L configurations are overridden when
the EM359x resets.
Refer to chapter 17 in the Ember EM359x Reference Manual for more information.
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