I see from the specs for SD and MMC cards that the time from a read block command is sent and the response is received until data actual is ready for reading, named Nac in timing constant definitions table, must be calculated from the TAAC and NSAC fields in the CSD register to ensure proper readback of data. However, setting a fixed time delay after response received would do the trick in most cases saving me from anoying calculations. For the bunch of you who have allready designed circuits using MMC and SD cards, what is your experience when it comes to this time value?
I guess most cards from different brands have a rather fast access time, but other peoples experience is always appreaciated. Would 1ms(+) do the trick? This is a common value for Hitachi MMC's according to Hitachi spec. where NSAC is set to 100 clk cycles (which when using 3.6864MHz SPI gives +24,13us) and TAAC is set to 1ms. For other card types I guess it is different timings. Your experience is???
Thanks in advance