MB87P2020 Datasheet, PDF (64/356 Pages) Fujitsu Component Limited. – Colour LCD/CRT/TV Controller

MB87J2120, MB87P2020-A Hardware Manual
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Figure 1-13: Interrupt display controller and MCU initialisation example
1.6.5 Display controller flags
All display controller flags are located in the Flagregister (FLNOM) inside ULB Interrupt Controller and
handled as described in section 1.6.1.
All flags are explained in appendix. Note that some flags are only available for Jasmine.
1.7 DMA handling
1.7.1 DMA interface
In order to improve data transfer speed and to automate FIFO load controlling during command execution
Lavender and Jasmine contain a DMA controller which operates together with DMA-Controller (DMAC)
integrated in MB91xxxx series MCUs. It is located inside ULB’s I/O-Controller and handles the display
controller DMA interface (GDC-DMAC).
This interface consists of additional control signals; data transfer is handled by I/O Controller as for normal
MCU accesses. The DMA connection between display controller and MCU is shown in figure 1-14.
The GDC-DMAC requests a DMA transfer by setting ULB_DREQ to ’1’; the MCU acknowledges this re-
quest by set ULB_DACK to ’0’ during a valid bus cycle. ULB_DACK-pulses for other devices connected to
MCU are ignored by GDC-DMAC because the ULB_DACK signal is gated with ULB_CSX for display con-
troller.
DMA
Interface
MCU
ULB_DREQ
ULB_DSTP
ULB_DACK
Lavender/
Jasmine
ULB
Figure 1-14: DMA connection between display controller and MB91xxxx
In order to stop the MCU-DMAC externally by display controller the DMA stop signal (ULB_DSTP) exist.
This signal creates an error condition inside MCU-DMAC that can also cause an interrupt (see MB91xxxx
manual for more details).
A better solution than using ULB_DSTP signal for disabling MCU-DMAC is to disable DMA in MCU first
by writing DMACAx_PAUS=0 and DMACAx_DENB=0 and turn off GDC-DMAC afterwards.The DSTP
pin at MCU is not needed in this case and can be used as general purpose I/O. Note that the ULB_DSTP pin
at display controller may not be supported in future display controller releases.
1.7.2 DMA modes
The MCU DMA-Controller can deliver/get data in two different ways:
1. ULB_DREQ Level triggered (Demand mode)
2. ULB_DREQ Edge triggered (Block-, Step- and Burstmode)
For a detailed description of supported DMA modes see MB91360 series hardware manual.
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