Sundance SMT335 - Manual (Page 12)

Version 3.0 Page 12 of 34 SMT335 User Manual
EMIF Control Registers
The C6000 contains several registers that control the external memory interface
(EMIF). There is one global control register and a separate register for each of the
memory spaces CE0 to CE3. A full description of these registers can be found in the
C60000 Peripherals Reference GuideError! Reference source not found.Error!
Reference source not found.[Error! Reference source not found.].
The standard bootstrap will initialise these registers to the following values:
GC (global control)
0x00003779
0x0000377D
For half speed SBSRAM
For full speed SBSRAM (default)
CE0 0x00000040 Indicates SBSRAM
CE1 0x30FF3F03 Defines asynchronous memory timings
CE2 0x00000030 Indicates SDRAM
CE3 0x00000030 VIRTEX FPGA
Note: Bits 12&13 of the Global control register are listed as 'reserved' in the current
TI documentation. With earlier versions of the C6000 silicon, these 2 bits controlled
the polarity of two clock outputs from the device. To maintain code compatibility for all
of our version modules, we have left our documentation with bits 12&13 set.
SBSRAM
Memory space CE0 is used to access 512KB of zero wait-state SBSRAM over the
C6000 external memory interface (EMI).
SBSRAM is normally set to run at the speed of the C6000 core clock, but the GC
register can be used to reduce this to one half of the core clock speed. The
appropriate setting has to be determined in conjunction with the C6000 core speed
and the external memory speed; refer to Clock Speed on page Error! Bookmark
not defined. for further details.
SDRAM
Memory space CE2 is used to access 16MB of SDRAM over the EMI. The SDRAM
operates at one half of the core clock speed.
FLASH
A 512KB Flash ROM device is connected to the C6000 EMI. This device is
accessed, a byte at a time, with word addresses from 0x0140 0000 to 0x015F FFFF
using strobe CE1 in 32-bit asynchronous mode. Each 32-bit load will give 8 bits of
data in bits 7–0 of the result; the state of bits 31–8 is undefined.