LCD Dedicated Channel
5-26
5.4
LCD Dedicated Channel
The LCD channel transfers 16-bit data to the LCD controller from a video frame
buffer stored in memory.
5.4.1
Functional Description
The memory source for the LCD dedicated transfer can be either IMIF or
EMIFF. These transfers can be arranged to one or two frames but they are
always done in frame addressing mode. There is no capability for various
addressing modes as in the other channels. The dual-frame mode allows
concurrent transfer and image processing (reload of one frame while another
is being processed).
Figure 5–10. LCD Channel
dma_first_word (17th bit)
IMIF
scheduler
IRQ_DMA_CH_LCD
FIFO and LCD
control logic
LCD
FIFO
64x17 bits
Read
control
logic
LCD address
unit (read)
dma_lcd_ram(15–0)
dma_lcd_enable
dma_lcd_ready
dma_lcd_un_flow
dma_lcd_add(5–0)
Interrupt
generator
LCD registers
IMIF
port
EMIFF
port
Priority (always high)
From/to generic channels
LCD
controller
EMIFF
scheduler
IMIF
EMIFF
TIPB
system DMA
LCD channel
Read address
Data (16-bits)
Asyncronous
RAM memory
Switching from one frame to another is achieved by loading the top address
of the second frame buffer after the first frame buffer has been fully transferred.
The LCD channel sends the read request on the relevant port according to the
LCD_SOURCE bit.
The LCD_SOURCE bit is read from the DMA_LCD_CTRL register. The dedi-
cated DMA channel contains a 64 by 17-bit words FIFO (asynchronous RAM
built-in). The dma_lcd_first_word that is used as frame synchronizer by the
LCD controller is the 17
th
FIFO bit output. To ensure correct throughput from