Hi,
I’m new to interfacing with SD cards… I have one of the “SparkFun microSD Transflash Breakout” boards that communicates over SPI. This question is specific to this board, but also more general in nature. How does one determine when the SD card is ready for the next byte? For example, there is no “busy or ready” signal (e.g. go low when “ready”). Does one normally just calculate the inter-byte gap/delay using the frequency, period, etc. and hope for the best?
Thanks for the help
From Wikipedia… Some devices require an additional flow control signal from slave to master, indicating when data is ready. This leads to a 5-wire protocol instead of the usual 4. Such a ready or enable signal is often active-low, and needs to be enabled at key points such as after commands or between words. Without such a signal, data transfer rates may need to be slowed down significantly, or protocols may need to have dummy bytes inserted, to accommodate the worst case for the slave response time. Examples include initiating an ADC conversion, addressing the right page of flash memory, and processing enough of a command that device firmware can load the first word of the response. (Many SPI masters do not support that signal directly, and instead rely on fixed delays.) - https://en.wikipedia.org/wiki/Serial_Pe … _Interface
So, yes, I just need to do the math…