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Ver.0.10
DMAC
9.4 Precautions about the DMAC
9.4 Precautions about the DMAC
• About writing to DMAC related registers
Because DMA transfer involves exchanging data via the internal bus, basically you only can write to
the DMAC related registers immediately after reset or when transfer is disabled (transfer enable bit
= 0). When transfer is enabled, do not write to the DMAC related registers because write operation
to those registers, except the DMA transfer enable bit, transfer request flag, and the DMA Transfer
Count Register which is protected in hardware, is instable.
The table below shows the registers that can or cannot be accessed for write.
Table 9.4.1 DMAC Related Registers That Can or Cannot Be Accessed for Write
Status
Transfer enable bit
Transfer request flag
Other DMAC related registers
When transfer is enabled
✕
When transfer is disabled
: Can be accessed ;
✕
: Cannot be accessed
For even registers that can exceptionally be written to while transfer is enabled, the following
requirements must be met.
➀
DMA Channel Control Register's transfer enable bit and transfer request flag
For all other bits of the channel control register, be sure to write the same data that those
bits had before you wrote to the transfer enable bit or transfer request flag. Note that you
only can write a 0 to the transfer request flag as valid data.
➁
DMA Transfer Count Register
When transfer is enabled, this register is protected in hardware, so that any data you write
to this register is ignored.
➂
Rewriting the DMA source and DMA destination addresses on different channels by DMA
transfer
In this case, you are writing to the DMAC related registers while DMA is enabled, but this
practically does not present any problem. However, you cannot DMA-transfer to the DMAC
related registers on the local channel itself in which you are currently operating.
Содержание M32170F3VFP
Страница 19: ...CHAPTER 1 CHAPTER 1 OVERVIEW 1 1 Outline of the 32170 1 2 Block Diagram 1 3 Pin Function 1 4 Pin Layout ...
Страница 42: ...1 1 24 Ver 0 10 OVERVIEW 1 4 Pin Layout This is a blank page ...
Страница 56: ...2 2 14 Ver 0 10 This is a blank page ...
Страница 88: ...3 3 32 Ver 0 10 ADDRESS SPACE 3 7 Notes on Address Space This is a blank page ...
Страница 192: ...6 6 58 Ver 0 10 INTERNAL MEMORY 6 9 Precautions to Be Taken When Rewriting Flash Memory This is a blank page ...
Страница 270: ...9 9 40 Ver 0 10 DMAC 9 4 Precautions about the DMAC This is a blank page ...
Страница 498: ...10 10 228 Ver 0 10 MULTIJUNCTION TIMERS 10 9 TOM Output related 16 bit Timer This is a blank page ...
Страница 550: ...11 11 52 Ver 0 10 A D CONVERTERS 11 4 Precautions on Using A D Converters This is a blank page ...
Страница 614: ...12 12 64 Ver 0 10 This is a blank page SERIAL I O 12 9 Precautions on Using UART Mode ...
Страница 710: ...14 14 16 Ver 0 10 REAL TIME DEBUGGER RTD 14 4 Typical Connection with the Host This is a blank page ...
Страница 746: ...16 16 20 Ver 0 10 WAIT CONTROLLER 16 3 Typical Operation of the Wait Controller This is a blank page ...
Страница 756: ...17 17 10 Ver 0 10 RAM BACKUP MODE 17 4 Exiting RAM Backup Mode Wakeup This is a blank page ...
Страница 757: ...CHAPTER 18 CHAPTER 18 OSCILLATION CIRCUIT 18 1 Oscillator Circuit 18 2 Clock Generator Circuit ...
Страница 762: ...18 18 6 Ver 0 10 OSCILLATION CIRCUIT 18 2 Clock Generator Circuit This is a blank page ...
Страница 798: ...19 19 36 Ver 0 10 JTAG 19 6 Precautions about Board Design when Connecting JTAG This is a blank page ...
Страница 830: ...21 21 24 Ver 0 10 PRELIMINARY PRELIMINARY This is a blank page ELECTRICAL CHARACTERISTICS 21 5 AC Characteristics ...
Страница 831: ...CHAPTER 22 CHAPTER 22 TYPICAL CHARACTERISTICS 22 1 A D Conversion Characteristics ...
Страница 833: ...Appendix 1 1 Dimensional Outline Drawing APPENDIX 1 APPENDIX 1 MECHANICAL SPECIFICATIONS ...
Страница 837: ...Appendix 2 1 32170 Instruction Processing Time APPENDIX 2 APPENDIX 2 INSTRUCTION PROCESSING TIME ...
Страница 841: ...Appendix 3 1 Precautions about Noise APPENDIX 3 APPENDIX 3 PRECAUTIONS ABOUT NOISE ...