
539
Chapter 31 External Bus
2.External Bus Interface Registers
When read by a Read - modify - Write instruction, the SELF, RRLD, and PON bits always return to 0.
(Bit 30) RRLD (Refresh counter ReLoaD): Refresh counter start control
This bit is used to start and reload the fresh counter.
Table 4.2-43 shows the function of refresh counter startup control.
The refresh counter is inactive in the initial state.
If this bit is set to 1 in this state, all the SDRAM areas currently enabled in the CSER are auto - refreshed either
once in distributed refresh mode or the RFC - specified number of times in centralized refresh mode. After that,
the values in the RFINT5 to RFINT0 bits are reloaded.
From then on, the refresh counter starts being decremented. Whenever the counter causes an underflow from
000000
B
, repeatedly, the values in the RFINT5 to RFINT0 bits are reloaded while at the same time auto -
refreshing is performed once.
The bit returns to 0 upon completion of reloading.
To stop auto - refreshing, write 000000
B
to the RFINT5 to RFINT0 bits.
When read by a Read - modify - Write instruction, the bit always returns a zero.
[Bits 29 - 24] RFINT5 to RFINT0 (ReFresh INTerval): Auto - refresh interval
Set these bits to the interval for automatic refreshing.
The auto - refresh interval can be obtained for distributed refresh mode {(REFINT5 - REFINT0 value) x 32 x
(external bus clock cycle)} or for centralized refresh mode {(REFINT5 - REFINT0 value) x 32 x (RFC specified
number of times) x (external bus clock cycle)}
Calculate the design value in consideration of the maximum RAS active time.
The refresh counter keeps on being decremented even while the auto - refresh command is being issued.
[Bit 23] BRST (BuRST refresh select): Burst refresh control
This bit is used to control the operation mode for auto - refreshing.
Table 4.2-44 shows the function of burst refresh control.
When distributed refreshing is set, the auto - refresh command is issued once at every refresh interval.
When burst refreshing is set, the auto - refresh command is issued continuously for the number of times set in the
refresh counter at every refresh interval.
Table 2-27 Function of refresh counter startup control
RRLD
Refresh counter startup control
0
Disable (no operation)
1
Execute auto - refreshing once and reload the RFINT value.
Table 2-28 Function of burst refresh control
BRST
Burst refresh control
0
Distributed refresh (Auto - refresh is activated at intervals.)
1
Burst refresh (Auto - refresh is activated repeatedly at one time.)
Summary of Contents for FR Family FR60 Lite
Page 2: ...FUJITSU LIMITED ...
Page 3: ...FR60 32 BIT MICROCONTROLLER MB91460 Series User s Manual ...
Page 15: ...xi ...
Page 16: ...xii ...
Page 38: ...22 Chapter 2 MB91460 Rev A Rev B Overview 4 Block Diagram ...
Page 128: ...112 Chapter 4 CPU Architecture 9 Addressing ...
Page 153: ...137 Chapter 8 Device State Transition 3 State Transition Diagram ...
Page 154: ...138 Chapter 8 Device State Transition 3 State Transition Diagram ...
Page 169: ...153 Chapter 9 Reset 10 Caution ...
Page 170: ...154 Chapter 9 Reset 10 Caution ...
Page 180: ...164 Chapter 10 Standby 7 Q A ...
Page 182: ...166 Chapter 10 Standby 8 Caution ...
Page 199: ...183 Chapter 12 Instruction Cache 2 Main body structure Figure 2 3 I Cache Address Map ...
Page 200: ...184 Chapter 12 Instruction Cache 2 Main body structure Figure 2 4 I Cacheable Area ...
Page 222: ...206 Chapter 13 Clock Control 8 Caution ...
Page 232: ...216 Chapter 14 PLL Interface 7 Caution ...
Page 236: ...220 Chapter 15 CAN Clock Prescaler 3 Registers ...
Page 288: ...272 Chapter 19 Timebase Timer 8 Caution ...
Page 314: ...298 Chapter 22 Main Oscillation Stabilisation Timer 8 Caution ...
Page 326: ...310 Chapter 23 Sub Oscillation Stabilisation Timer 8 Caution ...
Page 348: ...332 Chapter 25 External Interrupt 8 Caution ...
Page 398: ...382 Chapter 26 DMA Controller 6 DMA External Interface ...
Page 402: ...386 Chapter 27 Delayed Interrupt 8 Caution ...
Page 412: ...396 Chapter 28 Bit Search 8 Caution ...
Page 521: ...505 Chapter 30 I O Ports 3 Port Register Settings ...
Page 522: ...506 Chapter 30 I O Ports 3 Port Register Settings ...
Page 574: ...558 Chapter 31 External Bus 4 Endian and Bus Access Byte Access ...
Page 628: ...612 Chapter 31 External Bus 13 Notes on Using the External Bus Interface ...
Page 706: ...690 Chapter 33 I2C Controller 4 Programming Flow Charts ...
Page 748: ...732 Chapter 34 CAN Controller 4 CAN Application ...
Page 762: ...746 Chapter 35 Free Run Timer 8 Caution ...
Page 790: ...774 Chapter 37 Output Compare 8 Caution ...
Page 838: ...822 Chapter 39 Programmable Pulse Generator 8 Caution ...
Page 850: ...834 Chapter 40 Pulse Frequency Modulator 4 PFM Operation and Setting ...
Page 886: ...870 Chapter 42 Sound Generator 3 Registers ...
Page 900: ...884 Chapter 43 Stepper Motor Controller 4 Caution ...
Page 939: ...923 Chapter 47 LCD Controller 3 Configuration Figure 3 2 Register List ...
Page 943: ...927 Chapter 47 LCD Controller 4 Registers Correspondence between VRAM and Common Segment Pins ...
Page 964: ...948 Chapter 48 Clock Monitor 8 Caution ...
Page 994: ...978 Chapter 51 Low Voltage Reset Interrupt 3 Registers ...
Page 998: ...982 Chapter 52 Regulator Control 3 Registers ...
Page 1008: ...992 Chapter 53 Fixed Mode Reset Vector BOOT ROM 5 Bootloader Update Strategy ...
Page 1024: ...1008 Chapter 54 Flash Memory 8 Caution ...
Page 1032: ...1016 Chapter 55 Flash Security 4 Register ...
Page 1034: ...1018 Chapter 56 Electrical Specification ...
Page 1035: ...FR60 MB91460 Series Hardware Manual European Microcontroller Design Centre Author MBo ...
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