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EP2A15 数据表(PDF) 8 Page - Altera Corporation |
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EP2A15 数据表(HTML) 8 Page - Altera Corporation |
8 / 36 page Page 8 Functional Description Enhanced Configuration (EPC) Devices Datasheet January 2012 Altera Corporation FPGA Configuration FPGA configuration is managed by the configuration controller chip. This process includes reading configuration data from the flash memory, decompressing the configuration data, transmitting configuration data using the appropriate DATA[] pins, and handling error conditions. After POR, the controller determines the user-defined configuration options by reading its option bits from the flash memory. These options include the configuration scheme, configuration clock speed, decompression, and configuration page settings. The option bits are stored at flash address location 0x8000 (word address) and occupy 512-bits or 32-words of memory. These options bits are read using the internal flash interface and the default 10 MHz internal oscillator. After obtaining the configuration settings, the configuration controller chip checks if the FPGA is ready to accept configuration data by monitoring the nSTATUS and CONF _DONE signals. When the FPGA is ready (nSTATUS is high and CONF_DONE is low), the controller begins data transfer using the DCLK and DATA[] output pins. The controller selects the configuration page to be transmitted to the FPGA by sampling its PGM[2..0] pins after POR or reset. The function of the configuration unit is to transmit decompressed data to the FPGA, depending on the configuration scheme. The EPC device supports four concurrent configuration modes, with n = 1, 2, 4, or 8 (where n is the number of bits that are sent per DCLK cycle on the DATA[n] signals). The value n = 1 corresponds to the traditional PS configuration scheme. The values n = 2, 4, and 8 correspond to concurrent configuration of 2, 4, or 8 different PS configuration chains, respectively. Additionally, the FPGA can be configured in FPP mode, where eight bits of DATA are clocked into the FPGA per DCLK cycle. Depending on the configuration bus width (n), the circuit shifts uncompressed configuration data to the valid DATA[n] pins. Unused DATA[] pins drive low. In addition to transmitting configuration data to the FPGAs, the configuration circuit is also responsible for pausing configuration whenever there is insufficient data available for transmission. This occurs when the flash read bandwidth is lower than the configuration write bandwidth. Configuration is paused by stopping the DCLK to the FPGA, when waiting for data to be read from the flash or for data to be decompressed. This technique is called “Pausing DCLK”. The EPC device flash-memories feature a 90-ns access time (approximately 10 MHz). Hence, the flash read bandwidth is limited to about 160 megabits per second (Mbps) (16-bit flash data bus, DQ[], at 10 MHz). However, the configuration speeds supported by Altera FPGAs are much higher and translate to high configuration write bandwidths. For example, 100-MHz Stratix FPP configuration requires data at the rate of 800 Mbps (8-bit DATA[] bus at 100 MHz). This is much higher than the 160 Mbps the flash memory can support and is the limiting factor for configuration time. Compression increases the effective flash-read bandwidth as the same amount of configuration data takes up less space in the flash memory after compression. Since Stratix configuration data compression ratios are approximately two, the effective read bandwidth doubles to about 320 Mbps. |
类似零件编号 - EP2A15 |
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类似说明 - EP2A15 |
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