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MPC5553/MPC5554 Microcontroller Reference Manual, Rev. 5
Freescale Semiconductor
25-63
25.11.15.2 Block Write Access (Non-Burst Mode)
1. For a non-burst block write access, follow Steps 1, 2, and 3 outlined in
to initialize the registers,” but using a value greater than one (0x1) for the
RWCS[CNT] field.
2. The NZ6C3 module will then arbitrate for the system bus and transfer the first data value from the
RWD register to the memory mapped address in the read/write access address register (RWA).
When the transfer has completed without error (ERR = 0), the address from the RWA register is
incremented to the next word size (specified in the SZ field) and the number from the CNT field is
decremented. Nexus will then assert the RDY pin. This indicates that the device is ready for the
next access.
3. Repeat step 3 in
Section 25.11.15.1, “ Single Write Access
” until the internal CNT value is
zero (0). When this occurs, the DV bit within the RWCS will be cleared to indicate the end of the
block write access.
25.11.15.3 Block Write Access (Burst Mode)
1. For a burst block write access, follow Steps 1 and 2 outlined in
Section 25.11.15.1, “ Single Write
” to initialize the registers, using a value of four (doublewords) for the CNT field and a
RWCS[SZ] field indicating 64-bit access.
2. Initialize the burst data buffer (read/write access data register) through the access method outlined
Section 25.11.10, “ NZ6C3 Register Access via JTAG / OnCE
,” using the Nexus register
Index of 0xA (see
).
3. Repeat step 2 until all doubleword values are written to the buffer.
NOTE
The data values must be shifted in 32-bits at a time lsb first (that is,
doubleword write = two word writes to the RWD).
4. The Nexus module will then arbitrate for the system bus and transfer the burst data values from
the data buffer to the system bus beginning from the memory mapped address in the read/write
access address register (RWA). For each access within the burst, the address from the RWA
register is incremented to the next doubleword size (specified in the SZ field) modulo the length
of the burst, and the number from the CNT field is decremented.
5. When the entire burst transfer has completed without error (ERR = 0), NZ6C3 will then assert the
RDY pin, and the DV bit within the RWCS will be cleared to indicate the end of the block write
access.
NOTE
The actual RWA value as well as the CNT field within the RWCS are not
changed when executing a block write access (burst or non-burst). The
original values can be read by the external development tool at any time.
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