Synchronous burst write mode provides synchronous single or consecutive accesses.
Figure 12-83 shows a synchronous burst write access when the chip-select is configured in
address/data-multiplexed mode.
Figure 12-84 shows the same synchronous burst write access when the chip-select is configured
in address/address/data-multiplexed (AAD-multiplexed) mode.
The first data of the burst is driven on the A/D
bus at the GPMC_CONFIG6_i[19-16] WRDATAONADMUXBUS bit field.
When WRACCESSTIME completes, control-signal
timings are frozen during the multiple data transactions, corresponding to the
GPMC_CONFIG5_i[27-24] PAGEBURSTACCESSTIME bit field multiplied by the number of
remaining data transactions.
When the GPMC generates a read access to an address/data-multiplexed device, it drives the address bus until nOE assertion time. For more information, see Section 12.3.4.3.7.2.3, Address/Data-Multiplexing Interface.
- Chip-select signal nCS:
- nCS assertion time is controlled by the
GPMC_CONFIG2_i[3-0] CSONTIME bit field (where i = 0 to 3) and ensures
address setup time to nCS assertion.
- nCS deassertion time controlled by the
GPMC_CONFIG2_i[20-16] CSWROFFTIME bit field and ensures address hold
time to nCS deassertion.
- Address valid signal nADV:
- nADV assertion time is controlled by the
GPMC_CONFIG3_i[3-0] ADVONTIME bit field.
- nADV deassertion time is controlled by the
GPMC_CONFIG3_i[20-16] ADVWROFFTIME bit field.
- Write enable signal nWE:
- nWE assertion indicates a read cycle.
- nWE assertion time is controlled by the
GPMC_CONFIG4_i[19-16] WEONTIME bit field.
- nWE deassertion time is controlled by the
GPMC_CONFIG4_i[28-24] WEOFFTIME bit field.
Note:
The nWE falling
edge must not be used to control the time when the burst first
data is driven in the address/data bus, because some new devices
require the nWE signal to be low during the address phase.
- Direction signal DIR is OUT during the entire access.
When the GPMC generates a write access to an AAD-multiplexed device, all address bits are driven onto the address/data bus in two separate phases. The first phase is used for the MSB address and is qualified with nOE driven low. The second phase for LSB address is qualified with nOE driven high. The address phase ends at nWE assertion time.
The nCS, and DIR signals are controlled as previously described.
- Address valid signal nADV is asserted and deasserted twice during a read transaction:
- nADV first assertion time is controlled by the
GPMC_CONFIG3_i[6-4] ADVAADMUXONTIME bit field.
- nADV first deassertion time is controlled by the
GPMC_CONFIG3_i[26-24] ADVAADMUXRDOFFTIME bit field.
- nADV second assertion time is controlled by the
GPMC_CONFIG3_i[3-0] ADVONTIME bit field.
- nADV second deassertion time is controlled by the
GPMC_CONFIG3_i[12-8] ADVRDOFFTIME bit field.
- Output Enable signal nOE is asserted and deasserted twice during a read transaction (nOE second assertion indicates a read cycle):
- nOE first assertion time is controlled by the
GPMC_CONFIG4_i[6-4] OEAADMUXONTIME bit field.
- nOE first deassertion time is controlled by the
GPMC_CONFIG4_i[15-13] OEAADMUXOFFTIME bit field.
- nOE second assertion time is controlled by the
GPMC_CONFIG4_i[3-0] OEONTIME bit field.
- nOE second deassertion time is controlled by the
GPMC_CONFIG4_i[12-8] OEOFFTIME bit field.
First write data is driven by the GPMC at
GPMC_CONFIG6_i[19-16] WRDATAONADMUXBUS, when in address/data-multiplexed
configuration. The next write data of the burst is driven on the bus at WRACCESSTIME
+ 1 during GPMC_CONFIG5_i[27-24] PAGEBURSTACCESSTIME GPMC_FCLK cycles. The last data
of the synchronous burst write is driven until GPMC_CONFIG5_i[12-8] WRCYCLETIME
completes.
- WRACCESSTIME is defined in
the GPMC_CONFIG6_i[28-24] bit field.
- The PAGEBURSTACCESSTIME
parameter must be set accordingly with GPMCFCLKDIVIDER and the memory-device
internal configuration.
Total access time GPMC_CONFIG5_i[12-8] WRCYCLETIME corresponds to WRACCESSTIME
plus the address hold time from nCS deassertion. In
Figure 12-83, the programmed value of WRCYCLETIME equals WRCYCLETIME0 + WRCYCLETIME1.
WRCYCLETIME0 and WRCYCLETIME1 delays are not actual parameters and are only a
graphical representation of the full WRCYCLETIME value.
After a write operation, if no other access (read or write) is pending, the data bus keeps the previous value. See Section 12.3.4.3.8.10, Bus Keeping Support.