SWRU543B January 2019 – June 2025 CC3230S , CC3230SF , CC3235MODS , CC3235MODSF , CC3235S , CC3235SF
The clock division ratio is defined by the MCSPI_CHCONF[CLKD] register, with power of 2 granularity leading to a clock division in the range of 1 to 32768; in this case, the duty cycle is always 50%.
Table 8-3 provides clock ratio granularity.
| Clock Ratio Fratio | CLKSPIO High Time | CLKSPIO Low Time |
|---|---|---|
| 1 | Thigh_ref | Tlow_ref |
| Even ≥ 2 | T_ref × (Fratio/2) | T_ref × (Fratio/2) |
Table 8-4 lists granularity examples with a clock source frequency of 48 MHz.
| MCSPI_CHCONF [CLKD] | Fratio | MCSPI_CHCONF [PHA] | MCSPI_CHCONF [POL] | Thigh (ns) | Tlow (ns) | Tperiod (ns) | Duty Cycle | Fout (MHz) |
|---|---|---|---|---|---|---|---|---|
| 0 | 1 | X | X | 10.4 | 10.4 | 20.8 | 50-50 | 48 |
| 1 | 2 | X | X | 20.8 | 20.8 | 41.6 | 50-50 | 24 |
| 2 | 4 | X | X | 41.6 | 41.6 | 83.2 | 50-50 | 12 |
| 3 | 8 | X | X | 83.2 | 83.2 | 166.4 | 50-50 | 6 |