LFE2-20E-5FN256I Lattice, LFE2-20E-5FN256I Datasheet - Page 738

• Manufacturer Part Number: LFE2-20E-5FN256I
• Description: IC FPGA 21KLUTS 193I/O 256FPBGA
• Manufacturer: Lattice
• Series: ECP2r

Specifications of LFE2-20E-5FN256I

• Number Of Logic Elements/cells: 21000
• Number Of Labs/clbs: 2625
• Total Ram Bits: 282624
• Number Of I /o: 193
• Number Of Gates: -
• Voltage - Supply: 1.14 V ~ 1.26 V
• Mounting Type: Surface Mount
• Operating Temperature: -40°C ~ 100°C
• Package / Case: 256-BGA
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 220-1170; LFE2-20E-5FN256I; Q6411457

Lattice Semiconductor
Table 16-6. Encrypted File Format for a Slave Parallel Mode
Decryption Flow
From the user’s point of view, as compared to the encryption flow just discussed, the decryption flow is much sim-
pler.
When data comes into the FPGA the decoder starts looking for the preamble (see Figure 16-1) and all information
before the preamble is ignored. The preamble, along with the compression bit in Control Register 0, determines the
path of the configuration data.
If the decoder detects a standard bitstream preamble in the bitstream it knows that this is a non-encrypted data file.
The decoder then examines Control Register 0 in the bitstream to determine if the file has been compressed. If the
file has not been compressed then the Raw data path is selected (see Figure 16-1). If the file has been com-
pressed then the Decompressed path is selected; CRC is then checked and the SRAM fuses programmed.
If the decoder detects an encryption preamble in the bitstream it knows that this is an encrypted data file. If an
encryption key has not been programmed, the encrypted data is blocked and configuration fails (the DONE pin
stays low), if the proper key has been programmed then configuration can continue. The next block read contains
30,000 clocks of filler data. This delay allows time for the FPGA to read the key fuses and prepare the decryption
engine. The decoder keeps reading the filler data looking for the alignment preamble. Once found, it knows that the
following data needs to go through the decryption engine. It first looks for the standard preamble. Once found, then
it reads the Control Register 0 frame. The decoder then examines the decrypted Control Register 0 contents to
determine if the file has been compressed. If the file has not been compressed then the Decrypted data path is
used, if the file has been compressed then the decrypted data is passed through the decompression engine and
the Decompressed path is selected (refer to the block diagram, Figure 16-1). CRC is then checked and the SRAM
fuses programmed once the bitstream preamble is read. The decryption and decompression engines are turned off
Comments
Header
30,000 Filler Bytes
Alignment Preamble
Data
Program Done
End
Filler Bits
Delay
Dummy Data
Note:The data in this table is intended for reference only. The shaded area is encrypted data.
Frame
(Comment String) ASCII Comment (Argument) String and Terminator.
1111...1111
1111...1111
11111111
Contents
...
2 Dummy Bytes.
2-byte Encryption Preamble.
This allows time for the device to load and hash the 128-bit encryption key.
2-byte Alignment Preamble.
1-byte Dummy Data.
16 bytes of Configuration Data.
64 bytes (clocks) of all ones data. Provides a delay for the decryption engine to
decrypt the 16 bytes of data just received. If the peripheral device can provide the
needed 64 clocks while pausing data, then the 64 bytes of dummy data are not
required, saving file size.
16 bytes of Configuration Data.
64 bytes (clocks) of all ones data. Provides a delay for the decryption engine to
decrypt the 16 bytes of data just received. If the peripheral device can provide the
needed 64 clocks while pausing data, then the 64 bytes of dummy data are not
required, saving file size.
4-byte Program Done Command - Encrypted.
4-byte Terminator (all ones) - Encrypted.
Filler to meet the bound requirement.
64 bytes of all ones data. Delay to decrypt the Program Done command and the
filler.
200 bytes of Dummy Data (all ones), to provide delay to turn off the decryption
engine.
16-10
Configuration Encryption Usage Guide
Description
LatticeECP2/M S-Series