Digi NS9750 - Manual (Page 154)

S t a t i c m e m o r y c o n t r o l l e r
1 3 0 N S 9 7 5 0 H a r d w a r e R e f e r e n c e
Figure 45 shows a burst of zero wait state reads with the length specified. Because
the length of the burst is known, the chip select can be held asserted during the
whole burst and generate the external transfers before the current AHB transfer has
completed. The first read requires five arbitration cycles; the three subsequent
sequential reads have zero AHB arbitration cycles added because the external
transfers are automatically generated. Table 57 provides the timing parameters.
Table 58 describes the transactions for Figure 45.
Figure 45: External memory 0 wait fixed length burst read timing diagram
T7 AHB address provided to memory controller.
T7-T8 AHB transaction processing.
T8-T11 Arbitration of AHB memory ports.
T11-T12 Static memory address, chip select, and control signals submitted to
static memory.
T12-T13 Read data returned from static memory. Data is provided to the AHB.
Timing parameter Value
WAITRD 0
WAITOEN 0
WAITPAGE N/A
WAITWR N/A
Table 57: SRAM timing parameters
Cycle Description
Table 56: External memory 2 0wait state reads
ADDR
DATAIN
A+C
CSCTSOUT_n
COEOUT_n
A A+4 A+8
D(A)
D(A+4) D(A+8) D(A+C)
clk_out
T0 T1 T2 T3 T4 T5 T6 T7 T8