Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK Fiche De Données
Codes de produits
AT91SAM9N12-EK
380
SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]
11063K–ATARM–05-Nov-13
30.9.2 Read
Mode
As NCS and NRD waveforms are defined independently of one other, the SMC needs to know when the read data is
available on the data bus. The SMC does not compare NCS and NRD timings to know which signal rises first. The
READ_MODE parameter in the SMC_MODE register of the corresponding chip select indicates which signal of NRD and
NCS controls the read operation.
available on the data bus. The SMC does not compare NCS and NRD timings to know which signal rises first. The
READ_MODE parameter in the SMC_MODE register of the corresponding chip select indicates which signal of NRD and
NCS controls the read operation.
30.9.2.1 Read is Controlled by NRD (READ_MODE = 1):
PACC
after the falling edge of NRD, and turns to ‘Z’ after the rising edge of NRD. In this case, the READ_MODE must be set to
1 (read is controlled by NRD), to indicate that data is available with the rising edge of NRD. The SMC samples the read
data internally on the rising edge of Master Clock that generates the rising edge of NRD, whatever the programmed
waveform of NCS may be.
1 (read is controlled by NRD), to indicate that data is available with the rising edge of NRD. The SMC samples the read
data internally on the rising edge of Master Clock that generates the rising edge of NRD, whatever the programmed
waveform of NCS may be.
Figure 30-10. READ_MODE = 1: Data is sampled by SMC before the rising edge of NRD
Data Sampling
t
PACC
MCK
A[25:2]
NBS0,NBS1,
NBS2,NBS3,
A0, A1
NBS2,NBS3,
A0, A1
NCS
NRD
D[31:0]