EFM32WG Datasheet, PDF (198/834 Pages) List of Unclassifed Manufacturers – The EFM32WG Wonder Gecko is the ideal choice for demanding 8-, 16-, and 32-bit energy sensitive applications.

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If INTERLEAVE is limited to PORCH only and zero porch sizes are programmed in
the EBI_TFTHPORCH and EBI_TFTVPORCH registers, then no slots are left open for
interleaving traffic and therefore interleaving EBI accesses can never finish.
14.3.16.1 Direct Drive from Internal Memory
Any internal memory can be used as the frame source location for Direct Drive. Direct Drive display
from internal memory is started by setting the DD bitfield in the EBI_TFTCTRL register to INTERNAL.
The TFT controller indicates that the pixel buffer EBI_TFTDD is empty and needs to be filled by raising
the corresponding DMA request. This DMA request is initially set and it is cleared when EBI_TFTDD
is written. It is set again once the pixel data has been transferred to the display. One DMA request
is generated for each visible pixel. The Direct Drive engine will automatically align the data written to
EBI_TFTDD according to the setup and hold requirements with respect to EBI_DCLK and send it out
to the TFT via the EBI_AD lines. Whether the EBI_TFTDD buffer is full or empty is also signaled by the
DDEMPTY interrupt flag in the EBI_IF register and by the TFTDDEMPTY status bit in the EBI_STATUS
register. Given the relatively low performance of using software polling and interrupts compared to using
DMA, these non-DMA mechanisms are only advised for very low pixel rates. If pixel data is not provided
in time the EBI_DCLK will be stretched to accommodate the late pixel data and the Direct Drive Jitter
interrupt flag DDJIT in the EBI_IF register is set. Figure 14.34 (p. 198) shows the setup for Direct
Drive from internal memory.
Figure 14.34. EBI TFT Direct Drive from Internal Memory
EFM3 2
Mem ory
EBI_AD
DATA
EBI_DCLK
EBI
EBI_DATAEN
TFT
EBI_VSYNC, EBI_HSYNC
EBI_TFTCSn
14.3.16.2 Direct Drive from External Memory
Direct Drive can also use an external memory bank as the frame source location. The used bank is
defined in the BANKSEL bitfield of the EBI_TFTCTRL register. Direct Drive display from external memory
is started by setting the DD bitfield in the EBI_TFTCTRL register to EXTERNAL. Data is then streamed
directly from the external memory to the TFT. Figure 14.35 (p. 199) and Figure 14.36 (p. 199) show
the setup for Direct Drive from external memory when using non-multiplexed and multiplexed address
and data lines respectively.
2013-05-08 - Wonder Gecko Family - d0233_Rev0.50
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