237
8.8 Example of Using the Hold Request Cancel Request Function (HRCR)
■
Hold Request Cancel Request Sequence
❍
Example of interrupt routine
Figure 8.8-2 Example of Timing for Hold Request Cancel Request Sequence (Interrupt Level: HRCL > a)
The interrupt level changes when an interrupt request is issued. If the level is higher than that
set in the HRCL register, HRCR is activated for DMA, thereby causing DMA to cancel the hold
request, and the CPU returns from the hold state and performs interrupt processing. The
interrupt routine increments PDRR 1 to clear the interrupt cause 2, thereby changing the
interrupt level and rendering HRCR inactive. Accordingly, HRCR is inactivated to allow DMA to
issue a hold request, but the hold request is interrupted because PDRR is not 0. The hold
request is transmitted to the CPU to allow DMA transfer again only after PDRR is decremented
3.
❍
Example of multiple-interrupt routine
Figure 8.8-3 Example of Timing for Hold Request Cancel Request Sequence (Interrupt Level: HRCL > a
> b)
R U N
C P U
D H R Q
H R Q
H A C K
I R Q
L E V E L
a
R E T I
H R C R
P D R R
0 0 0 0
0 0 0 1
0 0 0 0
Bus hold
Interrupt processing
Bus hold (DMA transfer)
Example of interrupt routine
Incrementing PDRR
Clearing the interrupt cause
Decrementing PDRR
CPU
DHRQ
HRQ
HACK
IRQ1
IRQ2
LEVEL
a
b
a
HRCR
PDRR
0000
0001
0002
0001
0000
RUN
Bus hold
Interrupt I
Interrupt processing II
Interrupt processing I
Bus hold
Summary of Contents for MB91F109
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Page 3: ...FUJITSU LIMITED FR30 32 Bit Microcontroller MB91F109 Hardware Manual ...
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Page 96: ...72 CHAPTER 2 CPU ...
Page 224: ...200 CHAPTER 4 BUS INTERFACE ...
Page 234: ...210 CHAPTER 5 I O PORTS ...
Page 268: ...244 CHAPTER 9 U TIMER ...
Page 290: ...266 CHAPTER 10 UART ...
Page 314: ...290 CHAPTER 12 16 BIT RELOAD TIMER ...
Page 322: ...298 CHAPTER 13 BIT SEARCH MODULE ...
Page 392: ...368 CHAPTER 16 FLASH MEMORY ...
Page 432: ...408 APPENDIX E Instructions F Table E 2 Instruction Formats OP rel11 5 11 ...
Page 448: ...424 APPENDIX E Instructions ...
Page 449: ...425 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
Page 458: ...434 INDEX ...
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