37.10.2.1 Read is Controlled by NRD (READ_MODE = 1)
The figure below shows the waveforms of a read operation of a typical asynchronous RAM. The read data is available tPACC 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 the main system bus clock that generates the rising edge of NRD, whatever the programmed waveform of NCS.
