MMC2107 - Freescale Semiconductor

Freescale Semiconductor, Inc.
JTAG Test Access Port and OnCE
Functional Description
The FIFO is not affected by operations performed in debug mode,
except for incrementing the FIFO pointer when the FIFO is read. When
debug mode is entered, the FIFO counter points to the FIFO register
containing the address of the oldest of the eight change-of-flow
pre-fetches. The first FIFO read obtains the oldest address, and the
following FIFO reads return the other addresses from the oldest to the
newest, in order of execution.
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Freescale Semiconductor, I
21.14.14 Reserved Test Control Registers
CAUTION:
21.14.15 Serial Protocol
To ensure FIFO coherence, a complete set of eight reads of the FIFO
must be performed. Each read increments the FIFO pointer, causing it
to point to the next location. After eight reads, the pointer points to the
same location as before the start of the read procedure.
The reserved test control registers (MEM_BIST, FTCR, and LSRL) are
reserved for factory testing.
To prevent damage to the device or system, do not access these
registers during normal operation.
The serial protocol permits an efficient means of communication
between the OnCE external command controller and the MCU. Before
starting any debugging activity, the external command controller must
wait for an acknowledgment that the device has entered debug mode.
The external command controller communicates with the device by
sending 8-bit commands to the OnCE command register and 16 to 128
bits of data to one of the other OnCE registers. Both commands and data
are sent or received LSB first. After sending a command, the external
command controller must wait for the processor to acknowledge
execution of certain commands before it can properly access another
OnCE register.
MMC2107 – Rev. 2.0
Technical Data
MOTOROLA JTAG Test Access Port and OnCE 581
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