DMA Controller
MCF5253 Reference Manual, Rev. 1
14-10
Freescale Semiconductor
27–25
BWC
The three bandwidth control bits are decoded for internal bandwidth control. When the byte count reaches any
multiple of the programmed BWC boundary, the request signal to the internal arbiteris negated until data access
completes. This enables the arbiter to give another device access to the bus.
shows the encoding for these
bits. When the bits are cleared, the DMA does not negate its request. The 000 encoding asserts a priority signal
when the channel is active, signaling that the transfer has been programmed for a higher priority. When the BCR
reaches a multiple of the values shown in
, the bus is relinquished.
For example, if BWC = 001 (512 bytes or value of 0x0200), BCR24BIT = 0, and the BCR is set to 0x1000, the bus is
relinquished after BCR values of 0x2000, 0x1E00, 0x1C00, 0x1A00, 0x1800, 0x1600, 0x1400, 0x1200, 0x1000,
0x0E00, 0x0C00, 0x0A00, 0x0800, 0x0600, 0x0400, and 0x0200. In another example, BWC = 110, BCR24BIT = 0,
and the BCR is set to 33000. The bus is relinquished after transferring 232 bytes, because the BCR is at 32768,
which is a multiple of 16384.
24
DAA
Dual address access.
0 The DMA channel is in dual-address mode.
1 Reserved.
23
S_RW
Reserved, must be set to 0.
22
SINC
The source increment bit determines whether the source address increments after each successful transfer.
0 No change to the SAR after a successful transfer.
1 The SAR increments by 1, 2, 4, or 16; depending upon the size of the transfer.
21–20
SSIZE
The source size field determines the data size of the source bus cycle for the DMA control module.
shows the encoding for this field.
19
DINC
The destination increment bit determines whether the destination address increments after each successful transfer.
0 No change to the DAR after a successful transfer.
1 The DAR increments by 1, 2, 4, or 16; depending upon the size of the transfer.
Table 14-8. DMA Control Register (DCR) Field Descriptions (continued)
Field
Description
Table 14-9. BWC Encoding
BWC
Block Size
BCR24BIT = 0
BCR24BIT = 1
000
DMA has priority
001
512
16384
010
1024
32768
011
2048
65536
100
4096
131072
101
8192
262144
110
16384
524288
111
32768 1048576
Table 14-10. SSIZE Encoding
SSize
Transfer Size
00
Longword
01
Byte
10
Word
11
Line
Summary of Contents for MCF5253
Page 1: ...Document Number MCF5253RM Rev 1 08 2008 MCF5253 Reference Manual...
Page 26: ...MCF5253 Reference Manual Rev 1 xxvi Freescale Semiconductor...
Page 32: ...MCF5253 Reference Manual Rev 1 xxxii Freescale Semiconductor...
Page 46: ...MCF5253 Introduction MCF5253 Reference Manual Rev 1 1 14 Freescale Semiconductor...
Page 62: ...Signal Description MCF5253 Reference Manual Rev 1 2 16 Freescale Semiconductor...
Page 98: ...Instruction Cache MCF5253 Reference Manual Rev 1 5 10 Freescale Semiconductor...
Page 104: ...Static RAM SRAM MCF5253 Reference Manual Rev 1 6 6 Freescale Semiconductor...
Page 128: ...Synchronous DRAM Controller Module MCF5253 Reference Manual Rev 1 7 24 Freescale Semiconductor...
Page 144: ...Bus Operation MCF5253 Reference Manual Rev 1 8 16 Freescale Semiconductor...
Page 176: ...System Integration Module SIM MCF5253 Reference Manual Rev 1 9 32 Freescale Semiconductor...
Page 198: ...Analog to Digital Converter ADC MCF5253 Reference Manual Rev 1 12 6 Freescale Semiconductor...
Page 246: ...DMA Controller MCF5253 Reference Manual Rev 1 14 18 Freescale Semiconductor...
Page 282: ...UART Modules MCF5253 Reference Manual Rev 1 15 36 Freescale Semiconductor...
Page 344: ...Audio Interface Module AIM MCF5253 Reference Manual Rev 1 17 46 Freescale Semiconductor...
Page 362: ...I2 C Modules MCF5253 Reference Manual Rev 1 18 18 Freescale Semiconductor...
Page 370: ...Boot ROM MCF5253 Reference Manual Rev 1 19 8 Freescale Semiconductor...