9
9-54
Rev.1.0
(7) Ring buffer mode
When ring buffer mode is selected, operation starts from the transfer start address and when
transferred 32 times, returns to the transfer start address again, from which transfer operation
restarts. However, the 5 low-order bits of the ring buffer start address must always be B'00000.
The following describes how the addresses are incremented in ring buffer mode.
①
When the transfer size is 8 bits
The 27 high-order bits of the transfer start address are fixed, with the 5 low-order bits
incremented by one for each transfer performed. When the 5 low-order bits reach
B'11111 after performing transfers beginning with the start address, the bits are reset to
B'00000 by the next increment action, thus returning to the start address.
➁
When the transfer size is 16 bits
The 26 high-order bits of the transfer start address are fixed, with the 6 low-order bits
incremented by two for each transfer performed. When the 6 low-order bits reach
B'111110 after performing transfers beginning with the start address, the bits are reset to
B'000000 by the next increment action, thus returning to the start address.
It is the source address if the source has been set to increment or the destination address if the
destination has been set to increment that returns to the start address in this way.
If the source and destination addresses both have been set to increment, both addresses return
to the start address. However, the start addresses on either side must always have the 5 low-
order bits initially set to B'00000.
During ring buffer mode, the transfer counter register is ignored. After DMA operation starts, the
counter operates in free-running mode, with transfers continued until the transfer enable bit is
cleared to 0 (to disable transfers).
Figure 9.3.4 Typical Address Increment Action in 32-channel Ring Buffer Mode
DMAC
9.3 Functional Description of DMAC
<When the transfer size = 8 bits>
Transfer count
Transfer address
1
H'0080 1000
2
H'0080 1001
3
H'0080 1002
|
|
31
H'0080 101E
32
H'0080 101F
↓
↓
1
H'0080 1000
2
H'0080 1001
|
|
<When the transfer size = 16 bits>
Transfer count
Transfer address
1
H'0080 1000
2
H'0080 1002
3
H'0080 1004
|
|
31
H'0080 103C
32
H'0080 103E
↓
↓
1
H'0080 1000
2
H'0080 1002
|
|
Содержание 32172
Страница 20: ... This is a blank page 16 ...
Страница 21: ...1 1 Overview 1 2 Block Diagram 1 3 Pin Functions 1 4 Pin Layout CHAPTER 1 CHAPTER 1 OVERVIEW ...
Страница 44: ...1 1 24 Rev 1 0 This is a blank page Overview 1 4 Pin Layout ...
Страница 58: ...2 2 14 Rev 1 0 This is a blank page CPU 2 6 Data Formats ...
Страница 122: ...4 4 26 Rev 1 0 This is a blank page EIT 4 13 Precautions on EIT ...
Страница 200: ...7 7 6 Rev 1 0 This is a blank page RESET 7 4 Precautions to Be Taken Immediately after Reset ...
Страница 240: ...8 8 40 Rev 1 0 This is a blank page INPUT OUTPUT PORTS AND PIN FUNCTIONS 8 5 Precautions on Input Output Ports ...
Страница 298: ...9 9 58 Rev 1 0 This is a blank page DMAC 9 4 Precautions on Using DMAC ...
Страница 416: ...10 10 118 Rev 1 0 This is a blank page INPUT OUTPUT TIMERS 10 6 TOM Output Related 16 bit Timers ...
Страница 658: ...14 14 16 Rev 1 0 REAL TIME DEBUGGER RTD 14 4 Typical Connection with the Host This is a blank page ...
Страница 718: ...16 16 16 Rev 1 0 This is a blank page D A CONVERTERS 16 3 Functional Description of the D A Converters ...
Страница 766: ...18 18 22 Rev 1 0 WAIT CONTROLLER 18 3 Typical Operation of the Wait Controller This is a blank page ...
Страница 776: ...19 19 10 Rev 1 0 RAM BACKUP MODE 19 4 Exiting RAM Backup Mode Wakeup This is a blank page ...
Страница 777: ...CHAPTER 20 CHAPTER 20 OSCILLATION CIRCUIT 20 1 Oscillator Circuit 20 2 Clock Generator Circuit ...
Страница 782: ...20 20 6 Rev 1 0 OSCILLATION CIRCUIT 20 2 Clock Generator Circuit This is a blank page ...
Страница 856: ...23 23 26 Rev 1 0 This is a blank page ELECTRICAL CHARACTERISTICS 23 6 AC Characteristics ...
Страница 857: ...24 1 A D Conversion Characteristics CHAPTER 24 CHAPTER 24 STANDARD CHARACTERISTICS ...
Страница 859: ...Appendix 1 1 Dimensional Outline Drawing APPENDIX 1 APPENDIX 1 MECHANICAL SPECIFICATIONS ...
Страница 861: ...Appendix 2 1 M32R E Instruction Processing Time APPENDIX 2 APPENDIX 2 INSTRUCTION PROCESSING TIME ...
Страница 865: ...Appendix 3 1 Precautions about Noise APPENDIX 3 APPENDIX 3 PRECAUTIONS ABOUT NOISE ...