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AM186ED-20KC/W 数据表(PDF) 12 Page - Advanced Micro Devices |
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AM186ED-20KC/W 数据表(HTML) 12 Page - Advanced Micro Devices |
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12 / 88 page ![]() 12 Am186ED/EDLV Microcontrollers PRELI M INARY D RA F T COMPARING THE Am186ES/ESLV TO THE Am186ED/EDLV MICROCONTROLLERS Compared to the Am186ES/ESLV microcontrollers, the Am186ED/EDLV microcontrollers have the following additional features: n Integrated DRAM controller n Enhanced refresh control unit n Option to overlap DRAM with peripheral chip select (PCS) n Additional serial port mode for DMA support of 9-bit protocols n Option to boot from 8- or 16-bit memory n Improved external bus master support n PSRAM controller removed Figure 1 shows an example system using a 40-MHz Am18 6ED m i cr o c on tr o l le r. F i g u r e 2 sh ow s a comparable system implementation with an 80C186. Because of its superior integration, the Am186ED/ EDLV system does not require the support devices that are required on the 80C186 example system. In addition, the Am186ED/EDLV microcontrollers provide significantly better performance with its 40-MHz clock rate. Integrated DRAM Controller The integrated DRAM controller directly interfaces DRAM to support no-wait state DRAM interface up to 40 MHz. Wait states can be inserted to support slower DR AM. All signals requir ed by the DR AM ar e generated on the Am186ED/EDLV microcontrollers and no external logic is r equired. The DRAM multiplexed address pins are connected to the odd address pins starting with A1 on the Am186ED/EDLV microcontrollers to MA0 on the DRAM. The correct row and column addresses are generated on these pins during a DRAM access. The UCAS and LCAS are used to select which byte of the DRAM is accessed during a read or write. The RAS0 controls the lower bank of DRAM which starts at 00000h in the address map and is bounded by the lower memory size selected in the LMCS register. RAS1 controls the upper bank of DRAM which ends at FFFFFh and is bounded by the upper memory size in the UMCS register. When RAS1 is enabled, UCS is automatically disabled. Neither, either, or both DRAM banks can be activated. Figure 2. 80C186 Microcontroller Example System Design 25 |
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