美国爱特梅尔（Atmel）发布了基于ARM7并配备FPGA直连接口的MCU“AT91CAP7E”。AT91CAP7E在ARM7内核的MCU中内置了FPGA接口，CPU可将FPGA作为连接于MCU内部总线的器件进行操控。这样，便能够以低成本灵活构成集FPGA与MCU于一体的解决方案。
AT91CAP7E配备有6层AHB(Advanced High-speed Bus)、外围电路用DMA控制器以及160KB的片上SRAM。作为外围电路，配备了USB 2.0全速控制器、SPI主/从接口、2个UART、3个16bit的计时器、8通道/10bit的A/D转换器以及具有中断控制、功率控制及管理员功能的系统控制器。由于可将FPGA直接连接到AHB及DMA控制器上，因此，FPGA接口可减少与FPGA通信而导致的总线争夺，能够从CPU卸载通信，而且不会对外部总线及外部存储器的存取产生阻碍。
此前，MCU与FPGA间的通信或者基于EBI（External Bus Interface），或者采用程序I/O，无论哪种方式，与FPGA的通信均限制在平均每周期一个字节，这已成为阻碍通信速度的瓶颈。而CAP7E则是将2个AHB主控端和4个AHB从属端分配给FPGA，而且还配备了可直接存取外部RAM的特殊AHB从属端以及程序ROM(该区可重新映射到外部存储器，以用于调试)。此外，还备有14个APB（Advanced Peripheral Bus）从属端、2个全双层DMA通道以及32bit的程序I/O区。
目前，AT91CAP7E已开始供货，批量购买1万个时的单价为9.50美元。采用225针的BGA封装。
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, SPIｍａｓｔｅｒand 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.