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66
Lattice Semiconductor
Data Sheet
November 2006
ORCA Series 3C and 3T FPGAs
Microprocessor Interface (MPI) (continued)
MPI Setup and Control
The MPI has a series of addressable registers that provide MPI control and status, conguration and readback data
transfer, FPGA device identication, and a dedicated user scratchpad register. All registers are 8 bits wide. The
address map for these registers and the user-logic address space are shown in
Table 19, followed by descriptions
of the register and bit functions. Note that for all registers, the most signicant bit is bit 7, and the least signicant bit
is bit 0.
Table 19. MPI Setup and Control Registers
Control Register 1
The MPI control register 1 is a read/write register. The host processor writes a control byte to congure the MPI. It
is readable by the host processor to verify the status of control bits previously written.
Table 20. MPI Setup and Control Registers Descriptions
Address
(Hex)
Register
00
Control Register 1.
01
Control Register 2.
02
Scratchpad Register.
03
Status Register.
04
Conguration/Readback Data Register.
05
Readback Address Register 1 (bits [7:0]).
06
Readback Address Register 2 (bits [15:8]).
07
Device ID Register 1 (bits [7:0]).
08
Device ID Register 2 (bits [15:8]).
09
Device ID Register 3 (bits [23:16]).
0A
Device ID Register 4 (bits [31:24]).
0B—0F
Reserved.
10—1F
User-denable Address Space.
Bit #
Description
Bit 0
GSR Input.
Setting this bit to a 1 invokes a global set/reset on the FPGA. The host processor must
return this bit to a 0 to remove the GSR signal. GSR does not affect the registers at MPI addresses 0
through F hexadecimal or any conguration registers. Default state = 0.
Bit 1
Reserved.
Bit 2
Reserved.
Bit 3
Reserved.
Bit 4
Reserved.
Bit 5
RD_CFG
Input.
Changing this bit to a 0 after conguration will initiate readback. The host processor
must return this bit to a 1 to remove the RD_CFG signal. Since this bit works exactly like the RD_CFG
input pin, please see the FPGA pin descriptions for more information on this signal. Default state = 1.
Bit 6
Reserved.
Bit 7
PRGM
Input.
Setting this bit to a 0 causes the FPGA to begin conguration and resets the boundary-
scan circuitry. The host processor must return this bit to a 1 to remove the PRGM signal. Since this bit
works exactly like the PRGM input pin (except that it does not reset the MPI), please see the FPGA pin
descriptions for more information on this signal. Default state = 1.
Select
devices
have
been
discontinued.
See
Ordering
Information
section
for
product
status.