I have been reading more and more about bandwidths and frequencies to try to solve the following problem, but I am only ending up more confused. (I have limited electrical/signals background.)
I wish to communicate with an IC via SPI. The device has a max clock frequency of 8 MHz. I also need to use a logic level converter to convert between 5V micro-controller and the 3.3V device. I found a Logic Shifter online that states "the bandwidth on the individual signal channels can range from 20Mbps up to 100Mbps... suitable for higher speed signals such as SPI."
I am confused how to interpret the bandwidth of 20Mbps to 100Mbps in terms of my clock frequency for SPI.
Does the Mbps limit my clock frequency choices, and if so, why? From what I have read, bits-per-second and cycles-per-second measure different things, yet then I wonder why the manufacturer even bothered stating the Mbps range if it doesn't affect my SPI clock.
Answer
SPI is a fully synchronous serial protocol. For every clock cycle one bit is transferred.
There is, therefore. a 1:1 relationship between bits per second and hertz.
A 20MHz SPI bus runs at 20Mbps.
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