
271
CHAPTER 12 INTERRUPT CONTROLLER
12.7 Example of Using Hold-Request Cancellation-Request
Function (HRCR)
To let the CPU perform an operation with a higher priority during DMA transfer, the
DMA must release the hold state by canceling the hold request. In this case, use an
interrupt to cause the DMA to cancel the hold request. This allows the CPU to operate
with a higher priority.
■
Control register
❍
HRCL (Hold-request cancellation-level set register): this module
When an interrupt with the priority level higher than that specified in this register occurs, the
hold request cancellation request is issued to the DMA. This register is used to set the base
level.
❍
ICR: this module
For the ICR corresponding to the interrupt source used, set an interrupt level higher than that
specified in the HRCL register.
❍
PDRR (DMA request disable register): clock control block
This register temporarily disables a hold request from the DMA. It prevents the system from
entering the hold state again by clearing the interrupt source. A hold request from the DMA is
passed to the CPU only when this register is set to 0000
B
. The contents of this register must be
incremented at the beginning of the interrupt routine, and decremented at the end of the
interrupt routine.
■
Hardware configuration
The signal flow of each signal is shown below.
Figure 12.7-1 Sample hardware configuration for using a hold-request cancellation-request
IRQ
(ICR)
DMA
CPU
(HRCL)
HRCR
DHRQ (PDRR) HRQ
This module
Clock control block
DHRQ: DMA hold request
HRQ: Hold request
IRQ: Interrupt request
HRCR: Hold request cancellation request
Summary of Contents for MB91150 Series
Page 1: ......
Page 2: ......
Page 3: ...FUJITSU LIMITED FR30 32 BIT MICROCONTROLLER MB91150 Series HARDWARE MANUAL ...
Page 4: ......
Page 10: ...vi ...
Page 112: ...96 CHAPTER 3 MEMORY SPACE CPU AND CONTROL UNIT ...
Page 178: ...162 CHAPTER 5 I O PORTS ...
Page 214: ...198 CHAPTER 7 16 BIT RELOAD TIMER ...
Page 240: ...224 CHAPTER 8 PPG TIMER ...
Page 310: ...294 CHAPTER 13 8 10 BIT A D CONVERTER ...
Page 318: ...302 CHAPTER 14 8 BIT D A CONVERTER ...
Page 362: ...346 CHAPTER 15 UART ...
Page 420: ...404 CHAPTER 19 PERIPHERAL STOP CONTROL ...
Page 428: ...412 CHAPTER 20 CALENDAR MACROS ...
Page 503: ...487 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
Page 510: ...494 INDEX ...
Page 512: ......