Configuration Compression Algorithm Introduction AT6000 Series FPGAs are SRAM-based and can be reconfigured to perform different applications in a system. Formulas show how the act of reconfiguration affects system performance. A pr oprietary compression algorithm reduces reconfiguration time and improves system performance. This algorithm is incorporated into the bit stream generation software provided in the Integrated Development System. Description Two factors determine configuration time – the frequency of the configuration clock and the configuration mode used. The configuration clock, CCLK, regulates the loading of data. The higher the clock frequency, the faster data is loaded. Modes 4 and 5 use an internally supplied clock that runs at only 1 MHz. The other modes employ a user-supplied clock. The user-supplied clock can run as fast as 10 MHz. Of the two kinds of configuration, serial and parallel, parallel configuration is faster. Serial configuration loads one bit per clock cycle, while parallel configuration loads eight bits per clock cycle. As a result, a serial configuration mode takes eight times longer to load a bit stream. Table 1 gives equations that determine configuration times for the AT6002 and AT6005. Partial configuration is naturally faster than full configuration. A configuration compression algorithm, supplied with Atmel's development system, filters fullconfiguration data to produce a partial configuration bit stream. The bit stream produced by the compression algorithm only programs memory that is different from the present configuration. On power-up, for example, each cell in the array is a zero. The compression algorithm can remove all the zeros from the bit stream to be used after power-up – in some cases reducing the size of the bit stream by as much as 50%. Field Programmable Gate Array Application Note This reduction provides a proportional reduction in configuration time, as shown in Table 1. Table 1. Configuration Timing Equations Without Compression AT6002 AT6005 Serial 2678 × 8 × 1/Frequency 8077 × 8 × 1/Frequency Parallel 2678 × 1/Frequency 8077 × 1/Frequency With Compression AT6002 AT6005 Serial (1 - % Reduction) × 2678 × 8 × 1/Frequency (1 - % Reduction) × 8077 × 8 × 1/Frequency Parallel (1 - % Reduction) × 2678 × 1/Frequency (1 - % Reduction) × 8077 × 1/Frequency Rev. 0476C–09/99 1 Atmel Headquarters Atmel Operations Corporate Headquarters Atmel Colorado Springs 2325 Orchard Parkway San Jose, CA 95131 TEL (408) 441-0311 FAX (408) 487-2600 Europe 1150 E. Cheyenne Mtn. Blvd. Colorado Springs, CO 80906 TEL (719) 576-3300 FAX (719) 540-1759 Atmel Rousset Atmel U.K., Ltd. Coliseum Business Centre Riverside Way Camberley, Surrey GU15 3YL England TEL (44) 1276-686-677 FAX (44) 1276-686-697 Zone Industrielle 13106 Rousset Cedex France TEL (33) 4-4253-6000 FAX (33) 4-4253-6001 Asia Atmel Asia, Ltd. Room 1219 Chinachem Golden Plaza 77 Mody Road Tsimhatsui East Kowloon Hong Kong TEL (852) 2721-9778 FAX (852) 2722-1369 Japan Atmel Japan K.K. 9F, Tonetsu Shinkawa Bldg. 1-24-8 Shinkawa Chuo-ku, Tokyo 104-0033 Japan TEL (81) 3-3523-3551 FAX (81) 3-3523-7581 Fax-on-Demand North America: 1-(800) 292-8635 International: 1-(408) 441-0732 e-mail [email protected] Web Site http://www.atmel.com BBS 1-(408) 436-4309 © Atmel Corporation 1999. Atmel Corporation makes no warranty for the use of its products, other than those expressly contained in the Company’s standard warranty which is detailed in Atmel’s Terms and Conditions located on the Company’s web site. The Company assumes no responsibility for any errors which may appear in this document, reserves the right to change devices or specifications detailed herein at any time without notice, and does not make any commitment to update the information contained herein. No licenses to patents or other intellectual property of Atmel are granted by the Company in connection with the sale of Atmel products, expressly or by implication. Atmel’s products are not authorized for use as critical components in life support devices or systems. Marks bearing ® and/or ™ are registered trademarks and trademarks of Atmel Corporation. Terms and product names in this document may be trademarks of others. Printed on recycled paper. 0476C–09/99/xM