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   美國愛特梅爾（Atmel）發(fā)布了基于ARM7并配備FPGA直連接口的MCU“AT91CAP7E”。AT91CAP7E在ARM7內(nèi)核的MCU中內(nèi)置了FPGA接口，CPU可將FPGA作為連接于MCU內(nèi)部總線的器件進行操控。這樣，便能夠以低成本靈活構(gòu)成集FPGA與MCU于一體的解決方案。

　　AT91CAP7E配備有6層AHB(Advanced High-speed Bus)、外圍電路用DMA控制器以及160KB的片上SRAM。作為外圍電路，配備了USB 2.0全速控制器、SPI主/從接口、2個UART、3個16bit的計時器、8通道/10bit的A/D轉(zhuǎn)換器以及具有中斷控制、功率控制及管理員功能的系統(tǒng)控制器。由于可將FPGA直接連接到AHB及DMA控制器上，因此，F(xiàn)PGA接口可減少與FPGA通信而導(dǎo)致的總線爭奪，能夠從CPU卸載通信，而且不會對外部總線及外部存儲器的存取產(chǎn)生阻礙。

　　此前，MCU與FPGA間的通信或者基于EBI（External Bus Interface），或者采用程序I/O，無論哪種方式，與FPGA的通信均限制在平均每周期一個字節(jié)，這已成為阻礙通信速度的瓶頸。而CAP7E則是將2個AHB主控端和4個AHB從屬端分配給FPGA，而且還配備了可直接存取外部RAM的特殊AHB從屬端以及程序ROM(該區(qū)可重新映射到外部存儲器，以用于調(diào)試)。此外，還備有14個APB（Advanced Peripheral Bus）從屬端、2個全雙層DMA通道以及32bit的程序I/O區(qū)。

　　目前，AT91CAP7E已開始供貨，批量購買1萬個時的單價為9.50美元。采用225針的BGA封裝。

英文原文

ARM7-based MCU with FPGA Interface to Multi-layer AHB

Offers seamless migration to CAP7 customizable MCUs for ARM7-plus-FPGA designs

San Jose, CA, June 18, 2008…Atmel? Corporation (Nasdaq: ATML), today announced the AT91CAP7E, the industry's first ARM7?-based MCU with a direct FPGA interface. The AT91CAP7E is a standard microcontroller with an FPGA interface that makes the FPGA look and work like it is on the internal bus of the MCU. It provides customers with a two-chip, no-NRE, FPGA-plus ARM7 solution and offers an engineering-free migration path to a lower cost, and a lower power customizable MCU.

The CAP7E includes a six-layer advanced high-speed bus (AHB), peripheral DMA controller and 160 Kbytes of on-chip SRAM. On chip peripherals include USB 2.0 full speed device, SPI master and slave, two USARTs, three 16-bit timer counters, an 8-channel/ 10-bit analog to digital converter, plus a full-functioned system controller including interrupt and power control and supervisory functions. The FPGA interface on the CAP7E provides the FPGA with direct access to the CAP7E's on-chip AHB and peripheral DMA controller. This architecture eliminates FPGA-induced bus contention, off-loads MCU-to-FPGA communications from the CPU, and frees up the external bus interface for external memory access.

Interfacing an ARM7-based MCU to an FPGA has traditionally been done through the external bus interface (EBI) or programmable I/O. Either arrangement requires that the CPU transfer data to and from the FPGA one word-at-a-time, basically stealing CPU cycles that should be conserved for processing and limiting access to external memory during FPGA operations.

The FPGA interface on Atmel's CAP7E provides the FPGA with two AHB masters, four AHB slaves, a special direct AHB slave interface to an external RAM through the FPGA, and a programmable ROM that remaps the external RAM to emulate and debug the ROM code. Fourteen advanced peripheral bus (APB) slaves, two full-duplex DMA channels and 32-bit programmable I/O may be hardware selected to share I/O. An on-chip priority interrupt controller provides up to 13 encoded interrupts and two additional un-encoded interrupts for DMA transfers.

Third-party Tools and IP. The same C-compilers, RTOS, ICEs and IDEs used with Atmel's AT91SAM ARM?-based MCUs can be used with CAP?. Atmel has an extensive portfolio of silicon-proven peripherals that are available free of charge to customers migrating to a customizable MCU.

Availability and Pricing. Atmel's AT91CAP7E is available now and is priced at US$9.50 in quantities of 10,000 units in a 225 BGA package.