LCD Controller

7.6.6LCD DMA Frame Branch Registers (FBRx)

FBRx, one for each DMA channel, shown in Table 7-11, contain the addresses, aligned on a 4-byte boundary, of the descriptors to branch to.

When BRA is set, the Frame Descriptor Address Register is ignored. The next descriptor is fetched from the address in FBRx[31:4], regardless of whether frame data or palette RAM data is being processed. Setting BINT to one forces the DMAC to set the Branch Status interrupt bit (BS) in the LCD Controller Status Register after fetching the branched-to descriptor. BRA is automatically cleared by hardware when the branch is taken.

Note: In dual-panel mode, both FBR0 and FBR1 must be written in order to branch properly.

These are read/write registers. Ignore reads from reserved bits. Write zeros to reserved bits.

Table 7-11. FBRx Bit Definitions

Physical Address

channel 0: 0x4400_0020 LCD DMA Frame Branch RegistersLCD Controller

channel 1: 0x4400_0024

Bit 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

Frame Branch Address

Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

reserved

BINT

BRA

 

 

 

0 0 0 0 0 0 X X 0 0

Bits

Name

Description

 

 

 

 

Frame

Frame Branch Address:

31:4

Branch

Address of the descriptor for the branched-to frame.

 

Address

 

 

 

 

 

3:2

reserved

 

 

 

 

 

Branch Interrupt:

1

BINT

0 = Do not set the BS interrupt bit in register LCSR after the branched-to descriptor is

loaded.

 

 

 

 

1 = Set the BS interrupt bit in register LCSR after the branched-to descriptor is loaded.

 

 

 

 

 

Branch:

0

BRA

0 = Do not branch after finishing the current frame.

1 = Branch after finishing the current frame. The next descriptor will be fetched from the

 

 

 

 

Frame Branch Address. BRA is automatically cleared after loading the new descriptor.

 

 

 

Intel® PXA255 Processor Developer’s Manual

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Intel PXA255 LCD DMA Frame Branch Registers FBRx, FBRx Bit Definitions, Bint BRA, 0 0 0 0 X X 0 Bits Name Description