OR4 datasheet(62/152 Pages) LATTICE

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Lattice Semiconductor

Data Sheet

May, 2006

ORCA Series 4 FPGAs

Conﬁguration Data Format (continued)

Conﬁguration Data Frame

Conﬁguration data can be presented to the FPGA in two frame formats: autoincrement and explicit. A detailed

description of the frame formats is shown in Figure 36, Figure 37, and Tables Table 31 and Table 31A. The two

modes are similar except that autoincrement mode uses assumed address incrementation to reduce the bit stream

size, and explicit mode uses an optional address frame. In both cases, the header frame begins with a series of 1s

and a preamble of 0010, followed by a 24-bit length count ﬁeld representing the total number of conﬁguration

clocks needed to complete the loading of the FPGAs. If only Series 4 devices are used, a second preamble value

of 0100 is supported. If this preamble is found, the Series 4 device will expect an expanded length count ﬁeld of 32-

bits. This allows more larger Series 4 FPGAs to be conﬁgured through daisy-chaining.

Following the header frame is a mandatory ID frame. The ID frame contains data used to determine if the bit

stream is being loaded to the correct type of ORCA FPGA (i.e., a bit stream generated for an OR4E06 is being sent

to an OR4E06). Error checking is always enabled for Series 4 devices through the use of an 8-bit checksum. Fol-

lowing the ID frame is a 16-bit header to select the portion of the device to be conﬁgured with the following data. the

options are an FPGA header (shown in Table 32), an embedded RAM header (shown in Table 32A), and an FPSC

embedded block header (not shown).

A conﬁguration data frame follows the header frame. A data frame starts with a 01-start bit pair and ends with

enough 1-stop bit to reach a byte boundary. If subsequent data frames follow the frame address is auto-incre-

mented. If using explicit mode, an address frame can follow a data frame, telling the FPGA at what address to

update the auto-increment counter to for the next data frame. Address frame starts with 00.

Following all data and address frames is the postamble. The format of the postamble is the same as an address

frame with the highest possible address value with the checksum set to all ones, if no other sections of conﬁgura-

tion data follow. If another section is to follow, the header starts with 10.

5-5759(F)

Figure 36. Serial Conﬁguration Data Format—Autoincrement Mode

5-5760(F).a

Figure 37. Serial Conﬁguration Data Format—Explicit Mode

CONFIGURATION DATA

PREAMBLE LENGTH

ID FRAME

CONFIGURATION

POSTAMBLE

CONFIGURATION HEADER

COUNT

DATA FRAME 1

DATA FRAME 2

PREAMBLE LENGTH

ID FRAME

CONFIGURATION

POSTAMBLE

CONFIGURATION HEADER

ADDRESS

COUNT

DATA FRAME 1

DATA FRAME 2

FRAME 1

CONFIGURATION DATA

0 1

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