TC1796
System Units (Vol. 1 of 2)
LMB External Bus Unit
User’s Manual 13-46 V2.0, 2007-07
EBU, V2.0
13.7.5 Burst Phase (BP)
The Burst Phase is mandatory during burst read accesses. At the end of the Burst Phase
the EBU reads data from the data bus. During a burst read access, Burst Phases are
repeated as many times as required in order to read the required amount of data from
the Burst Flash device.
At the start of the first Burst Phase during a burst read access, the EBU:
• Drives the BAA signal low to cause the Burst Flash device to advance the address
with each subsequent BFCLKO positive edge.
At the end of the last Burst Phase during a burst read access, the EBU:
• Returns the BAA signal high,
• Returns the CSx signal high,
• Returns the RD signal high.
The total number of Burst Phase cycles is calculated by multiplying the
EBU_BUSAPx.BURSTC parameter with EBU_BUSCONx.CMULT but only if bit
EBU_BUSCONx.MULTMAP[3] is set (BURSTC multiplier function enabled).
The calculation of the number of Burst Phase cycles is defined by the following table:
The equivalent control capability is available for bit field EBU_EMUBAP.BURSTC, which
is multiplied by EBU_EMUBC.CMULT.
During accesses to Burst Flash devices the length of the Burst Phase must be
programmed such that the end of the Burst Phase always coincides with a positive edge
of the appropriate BFCLKO (Burst Flash Clock) signal.
MULTMAP Number of Burst Phase Cycles
XXX0XXX
B
= BURSTC
XXX1XXX
B
= BURSTC × CMULT
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