Panasonic MN103001G/F01K User Manual
Page 180
Bus Controller (BC)
8-66
8.14.3
Software Page Mode
Software page mode is a mode that forcibly initiates page mode by setting the control register.
Operation within software page mode is as described below. Refer to Fig. 8-14-6.
•
When the mode is initiated, the contents of PRAR are output as the row address.
•
While the mode is in effect, RASn for the block corresponding to the memory control register that initiated the
mode is maintained in the asserted state.
•
After the mode is initiated, external accesses are all processed
as column address accesses
. In this case,
the ASC and CAS parameters of the block in question are guaranteed. In addition, the RE/WE signal has the
same waveform as in a normal DRAM access.
•
The CAS precharge interval depends on the timing of the external access. Note that the shortest CAS precharge
interval is ASC + 3 for a read, or ASC + 1 for a write. As an example, Fig. 8-14-6 illustrates the case where the
CAS precharge interval is at its shortest.
•
(CAO + 1) MCLK pulses are guaranteed for the row address output interval. (“CAO” is a parameter.)
•
The parameter ASR for the block in question is guaranteed for the assertion of RASn.
The procedure for executing this mode is described below:
■
Preparation for mode initiation
(1) Set the row address in the row address register PRAR.
Set a row address that has already been shifted according to the DRAM size.
(2) Set DRAMCTR.
Be certain to set the PAGE bit to “1” and the DRAME bit to “1”.
■
Mode initiation
Once the PE bit of the memory control register for the block in question (block 1 or 2) is set to “1”, software
page mode access begins after the register writing operation has been completed.
■
Mode termination
Once the PE bit of the memory control register for the block in question (block 1 or 2) is set to “0”, software
page mode is terminated after the register writing operation has been completed.
Note: When performing ICE trace/emulation in software page mode, set the CAS parameter to “5” or higher.