User`s manual
RTD Embedded Technologies, Inc. | www.rtd.com   23  FPGA35S6 User’s Manual 
5 Functional Description 
5.1  Block Diagram 
The Figure below shows the functional block diagram of the FPGA35S6. The various parts of the block diagram are discussed in the following 
sections. 
Figure 7: FPGA35S6 Block Diagram 
5.2  Oscillator 
The FPGA35S6 features a 27 MHz oscillator for clock based operations in the FPGA. 
5.3  EEPROM 
The FPGA35S6 features a 256 x 16 SPI EEPROM, ATMEL AT93C66A. For information on the AT93C66A refer to http://www.atmel.com/ 
5.4  DDR2 SRAM 
The FPGA35S6 features a 1Gb DDR2 SRAM, MT47H64M16HR 25E. This is interface to the Spartan 6 FPGA using Xilinx Memory Interface 
Generators (MIG) core. The example FPGA code has demonstrated how to use this core in a FPGA design. 
PCIe Bus 
PCIe x1 
Link 
Xilinx 
Spartan 6  
Oscillator 
Level Shifter 
Digital I/O CN4 and CN9 
DDR2 SRAM
X2 
X2 
High Speed Digital I/O CN8 
EEPROM 










