Description
Subtract requiredIdle from actualIdle for slack and compare the two nonnegative durations inclusively for meetsRequirement.
SPI clock polarity determines idle level and the first transition; clock phase determines which edge samples data. Word and idle budgets describe separate parts of the transfer.
Subtract requiredIdle from actualIdle for slack and compare the two nonnegative durations inclusively for meetsRequirement.
When to use this tool
Use SPI Chip Select Idle Slack when you need an explicit SPI mode or clock-budget component.
How to use the tool and how it works
- Enter actualIdle, requiredIdle. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read slack, meetsRequirement. Inspect meetsRequirement before interpreting the associated values.
Subtract requiredIdle from actualIdle for slack and compare the two nonnegative durations inclusively for meetsRequirement.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| actualIdle | Actual Idle | Required. Finite number; minimum 0. |
| requiredIdle | Required Idle | Required. Finite number; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| slack | Slack | Required. Finite number. |
| meetsRequirement | Meets Requirement | Required. Boolean. |
{
"input": {
"actualIdle": 5,
"requiredIdle": 3
},
"output": {
"slack": 2,
"meetsRequirement": true
}
}Limitations and assumptions
- Use matching units; the required interval is caller supplied and electrical timing is not measured.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Compare both devices' timing requirements and verify the actual chip-select and clock waveform.
References
Similar or alternative tools
- SPI Idle Level Sample Sign
Use CPOL to choose the leading edge and CPHA to select the leading or trailing sampling edge.
- SPI Interword Idle Clock Count
Multiply idleSeconds by clockHz and round up or down according to roundUp.