Meaning
Set of temporal constraints governing the exchange of command and address signals between a serial peripheral interface master controller and a non-volatile flash memory chip. Properly configured SPI flash timing guarantees that data is read and written without corruption. The limits are measured in nanoseconds and are specified in the memory device datasheet.
They dictate the maximum clock frequency at which the memory can operate.
Dynamic Characteristic
The host controller must hold the serial clock line stable during critical read and write cycles. In every SPI flash timing cycle, the setup and hold times of the data lines relative to the clock edges are paramount. If the data transitions too close to the active clock edge, the memory chip reads unstable states.
The controller must also respect the minimum chip-select high time between consecutive instructions to allow internal state machines to reset.
Signal Integrity
Printed circuit board traces must be matched in length to prevent skew between the clock and data lines. High frequencies require inline termination resistors to damp signal reflections. These reflections can cause false triggering of the clock line, leading to timing violations.
Clock Margin
Engineers use high-bandwidth oscilloscopes to measure the rise and fall times during the qualification phase. This validation verifies that the system operates with sufficient timing margin under extreme temperatures.
