HD64F2676VFC33 Renesas Electronics America, HD64F2676VFC33 Datasheet - Page 242

• Manufacturer Part Number: HD64F2676VFC33
• Description: IC H8S MCU FLASH 256K 144-QFP
• Manufacturer: Renesas Electronics America
• Series: H8® H8S/2600r

Specifications of HD64F2676VFC33

• Core Processor: H8S/2600
• Core Size: 16-Bit
• Speed: 33MHz
• Connectivity: IrDA, SCI
• Peripherals: DMA, POR, PWM, WDT
• Number Of I /o: 103
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Ram Size: 8K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Data Converters: A/D 12x10b; D/A 4x8b
• Oscillator Type: Internal
• Operating Temperature: -20°C ~ 75°C
• Package / Case: 144-QFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

Section 6 Bus Controller (BSC)
6.6.12
This LSI is provided with a DRAM refresh control function. CAS-before-RAS (CBR) refreshing
is used. In addition, self-refreshing can be executed when the chip enters the software standby
state.
Refresh control is enabled when any area is designated as DRAM space in accordance with the
setting of bits RMTS2 to RMTS0 in DRAMCR.
CAS-before-RAS (CBR) Refreshing: To select CBR refreshing, set the RFSHE bit to 1 in
REFCR.
With CBR refreshing, RTCNT counts up using the input clock selected by bits RTCK2 to RTCK0
in REFCR, and when the count matches the value set in RTCOR (compare match), refresh control
is performed. At the same time, RTCNT is reset and starts counting up again from H'00.
Refreshing is thus repeated at fixed intervals determined by RTCOR and bits RTCK2 to RTCK0.
Set a value in RTCOR and bits RTCK2 to RTCK0 that will meet the refreshing interval
specification for the DRAM used.
When bits RTCK2 to RTCK0 in REFCR are set, RTCNT starts counting up. RTCNT and RTCOR
settings should therefore be completed before setting bits RTCK2 to RTCK0. RTCNT operation is
shown in figure 6.34, compare match timing in figure 6.35, and CBR refresh timing in figure 6.36.
When the CBRM bit in REFCR is cleared to 0, access to external space other than DRAM space is
performed in parallel during the CBR refresh period.
Rev. 3.00 Mar 17, 2006 page 190 of 926
REJ09B0283-0300
RTCOR
H'00
Refresh request
Refresh Control
RTCNT
Figure 6.34 RTCNT Operation