Rainbow Electronics AT91CAP9S250A - Manual (Page 176)

176
6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
22.8.1 Read Waveforms
The read cycle is shown on Figure 22-8 .
The read cycle starts with the address setting on the memory address bus, i.e.:
{A[25:2], A1, A0} for 8-bit devices
{A[25:2], A1} for 16-bit devices
A[25:2] for 32-bit devices.
Figure 22-8. Standard Read Cycle
22.8.1.1 NRD Waveform
The NRD signal is characterized by a setup timing, a pulse width and a hold timing.
1. NRD_SETUP: the NRD setup time is defined as the setup of address before the NRD
falling edge;
2. NRD_PULSE: the NRD pulse length is the time between NRD falling edge and NRD
rising edge;
3. NRD_HOLD: the NRD hold time is defined as the hold time of address after the NRD
rising edge.
A[25:2]
NBS0,NBS1,
NBS2,NBS3,
A0, A1
NCS
NRD_SETUP NRD_PULSE NRD_HOLD
MCK
NRD
D[31:0]
NCS_RD_SETUP NCS_RD_PULSE NCS_RD_HOLD
NRD_CYCLE