Spectrum Digital eZdsp R2812 USB, Technical Reference, Page: 17 / 46

Spectrum Digital, Inc
2-5
2.2.2 External Memory Timing
This section describes the timing for the external memory bus when the R2812 is
operating at 150 Mhz. In addition a segment of ‘C’ code is provided to configure the
EMIF.
The following ‘C’ code segment will initialize the EMIF for 150 Mhz operation.
#define XINTCNF2 ( 0x13 )
#define XWRTRAIL(x) ((x & 3))
#define XWRACTIVE(x) ((x & 7)<<2)
#define XWRLEAD(x) ((x & 3)<<5)
#define XRDTRAIL(x) ((x & 3)<<7)
#define XRDACTIVE(x) ((x & 7)<<9)
#define XRDLEAD(x) ((x & 3)<<12)
#define USEREADY (1<<14)
#define ASYNCREADY (1<<15)
#define XTIMING6 (XWRTRAIL(2) | \
XWRACTIVE(1) | \
XWRLEAD(2) | \
XRDTRAIL(2) | \
XRDACTIVE(3) | \
XRDLEAD(2) )
XINTF_Init()
{
*(unsigned long *)0xB2C = (unsigned long)XTIMING6;
*(unsigned long *)0xB34 = (unsigned long)XINTCNF2;
}
Table 2: External Memory Timing
Memory
Function
Time in ns.
Write Cycle Time 40.4ns
Write Low Time 14.0ns
Write High Time 26.4ns
Read Cycle Time 60.8ns
Read Low Time 26.8ns
Read High Time 34.0ns