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參數(shù)資料
| 型號： | UPD70741GC-25-8EU |
| 廠商： | NEC Corp. |
| 元件分類： | 16位微控制器 |
| 英文描述： | V821TM 32-/16-BIT MICROPROCESSOR |
| 中文描述： | V821TM 32-/16-BIT微處理器 |
| 文件頁數(shù)： | 32/112頁 |
| 文件大?。?/td> | 605K |
| 代理商： | UPD70741GC-25-8EU |
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μ
PD70741
32
6. MEMORY ACCESS CONTROL FUNCTIONS
6.1 DRAM Controller (DRAMC)
The DRAM controller (DRAMC) generates the REFRQ, RAS, LCAS, and UCAS signals, and controls access to
DRAM. Access to DRAM is achieved by multiplexing the DRAM row and column addresses and outputting them from
the address pins.
The microprocessor assumes the connected DRAM to be of
×
4 bits or more, and that it supports high-speed page
mode. There are two types of DRAM access cycles, on-page (2 or 3 clock pulses) and off-page (4 or 5 pulses).
Refresh uses the CAS before RAS method, allowing the user to set any refresh period. In IDLE and STOP modes,
CBR self-refresh is performed.
6.1.1 Features
Generates the REFRQ, RAS, LCAS, and UCAS signals.
Supports DRAM high-speed page mode.
Address multiplexing function: 8, 9, 10, and 11 bits
CBR refresh and CBR self-refresh functions
6.1.2 Address multiplexing function
In the DRAM cycle, row and column addresses are multiplexed according to the value of the DAW bits of the DRAM
configuration register (DRC), then output, as shown in Figure 6-1. In Figure 6-1, a0-a23 are the addresses output
from the CPU, while A0-A23 are the address pins of the V821. For example, if DAW = 11, row address a12-a22 and
column address a1-a11 are output from address pins (A1-A11).
Table 6-1 lists the relationship between the connectable DRAMs and address multiplexing widths. Depending on
the connected DRAM, the DRAM space can be between 128 Kbytes and 8 Mbytes.
Figure 6-1. Output of Row and Column Addresses
a23
a16
a15 a14
a13 a23
a22
a21 a20
a19 a18
a17
a16
a15 a14
a13 a12
a11
A23
A16
A15 A14 A13 A12 A11 A10 A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
a23
a16
a15 a14
a23 a22
a21
a20 a19
a18 a17
a16
a15
a14 a13
a12 a11
a10
a23
a16
a15 a23
a22 a21
a20
a19 a18
a17 a16
a15
a14
a13 a12
a11 a10
a9
a23
a16
a23 a22
a21 a20
a19
a18 a17
a16 a15
a14
a13
a12 a11
a10
a9
a8
a23
a0
Address pin
Row address
DAW = 11
DAW = 10
DAW = 01
DAW = 00
Column address
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| UPD70F3003A | V853TM 32-/16-BIT SINGLE-CHIP MICROCONTROLLER |
| UPD70F3003AGC-25-8EU | Circular Connector; No. of Contacts:24; Series:MS27467; Body Material:Aluminum; Connecting Termination:Crimp; Connector Shell Size:25; Circular Contact Gender:Pin; Circular Shell Style:Straight Plug; Insert Arrangement:25-24 RoHS Compliant: No |
| UPD70F3025AGC-25-8EU | V853TM 32-/16-BIT SINGLE-CHIP MICROCONTROLLER |
| UPD70F3003AGC-33-8EU | LJT 29C 29#16 PIN PLUG |
| UPD70F3025AGC-33-8EU | LJT 29C 29#16 PIN PLUG |
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參數(shù)描述 |
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| UPD70742GD-25-LML | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:32-Bit Microprocessor |
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| UPD70F30025AGC-33 | 制造商:NEC 制造商全稱:NEC 功能描述:32-bit RISC Microcontrollers |
| UPD70F3003A | 制造商:NEC 制造商全稱:NEC 功能描述:V853TM 32-/16-BIT SINGLE-CHIP MICROCONTROLLER |
| UPD70F3003AGC(A)-33-8EU-A | 制造商:Renesas Electronics Corporation 功能描述: |
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