ATSAM3U-EK Atmel, ATSAM3U-EK Datasheet - Page 368

• Manufacturer Part Number: ATSAM3U-EK
• Description: KIT EVAL FOR AT91SAM3U CORTEX
• Manufacturer: Atmel
• Type: MCUr

Specifications of ATSAM3U-EK

• Contents: Board
• Processor To Be Evaluated: SAM3U
• Data Bus Width: 32 bit
• Interface Type: RS-232, USB
• Operating Supply Voltage: 3 V
• Silicon Manufacturer: Atmel
• Core Architecture: ARM
• Core Sub-architecture: Cortex - M3
• Silicon Core Number: SAM3U4E
• Silicon Family Name: SAM3U
• Kit Contents: Board CD Docs
• Rohs Compliant: Yes
• For Use With/related Products: AT91SAM3U
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

25.12.2
Figure 25-14. Early Read Wait State: Write with No Hold Followed by Read with No Setup
368
368
SAM3U Series
SAM3U Series
Early Read Wait State
NBS0, NBS1,
A0, A1
In some cases, the SMC inserts a wait state cycle between a write access and a read access to
allow time for the write cycle to end before the subsequent read cycle begins. This wait state is
not generated in addition to a chip select wait state. The early read cycle thus only occurs
between a write and read access to the same memory device (same chip select).
An early read wait state is automatically inserted if at least one of the following conditions is
valid:
D[15:0]
A[23:2]
• if the write controlling signal has no hold time and the read controlling signal has no setup
• in NCS write controlled mode (WRITE_MODE = 0), if there is no hold timing on the NCS
• in NWE controlled mode (WRITE_MODE = 1) and if there is no hold timing (NWE_HOLD =
NWE
MCK
NRD
time
signal and the NCS_RD_SETUP parameter is set to 0, regardless of the read mode
25-15). The write operation must end with a NCS rising edge. Without an Early Read Wait
State, the write operation could not complete properly.
0), the feedback of the write control signal is used to control address, data, chip select and
byte select lines. If the external write control signal is not inactivated as expected due to load
capacitances, an Early Read Wait State is inserted and address, data and control signals are
maintained one more cycle. See
(Figure
25-14).
write cycle
no hold
Early Read
wait state
Figure
25-16.
no setup
read cycle
6430D–ATARM–25-Mar-11
6430D–ATARM–25-Mar-11
(Figure