NXP Semiconductors LPC1768 - Page 614

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User manual Rev. 3 — 19 December 2013 614 of 841
NXP Semiconductors
UM10360
Chapter 31: LPC176x/5x General Purpose DMA (GPDMA)
The first LLI, stored at 0x2002 0000, defines the first block of data to be transferred, which
is the data stored from address 0x2002 A200 to 0x2002 ADFF:
• Source start address 0x2002 A200.
• Destination address set to the destination peripheral address.
• Transfer width, word (32-bit).
• Transfer size, 3072 bytes (0XC00).
• Source and destination burst sizes, 16 transfers.
• Next LLI address, 0x2002 0010.
The second LLI, stored at 0x2002 0010, describes the next block of data to be transferred:
• Source start address 0x2002 B200.
• Destination address set to the destination peripheral address.
• Transfer width, word (32-bit).
• Transfer size, 3072 bytes (0xC00).
• Source and destination burst sizes, 16 transfers.
• Next LLI address, 0x2002 0020.
A chain of descriptors is built up, each one pointing to the next in the series. To initialize
the DMA stream, the first LLI, 0x2002 0000, is programmed into the DMA Controller.
When the first packet of data has been transferred the next LLI is automatically loaded.
The final LLI is stored at 0x2002 0070 and contains:
Fig 135. LLI example
LLI1
0x2002 0000
Source address = 0x 2002 A200
Destination address = peripheral
Next LLI address = 0x2002 0010
Control information = length 3072
Source address = 0x 2002 B200
Destination address = peripheral
Next LLI address = 0x2002 0020
Control information = length 3072
Source address = 0x 2002 C200
Destination address = peripheral
Next LLI address = 0x2002 0030
Control information = length 3072
Source address = 0x 2003 1200
Destination address = peripheral
Next LLI address = 0 (end of list)
Control information = length 3072
LLI2
0x2002 0010
LLI3
0x2002 0020
LLI8
0x2002 0070
Linked List Array
3072 bytes of data
0x2002 A200
0x2002 ADFF
3072 bytes of data
0x2002 B200
0x2002 BDFF
3072 bytes of data
0x2002 C200
0x2002 CDFF
3072 bytes of data
0x2003 1200
0x2003 1DFF