SPRUJD3A July 2025 – October 2025 F28E120SB , F28E120SC
Memory-mapped registers in the System Control operate on OSCCLK clock domain; hence, any CPU writes to these registers requires a delay between subsequent writes otherwise a second write can be lost. The application needs to take this into consideration and add a delay in terms of the number of NOP instructions after every write to these registers that are mentioned in Table 3-16. The formula to compute delay between subsequent writes:
Delay (in SYSCLK cycles) = 3 × (FSYSCLK ÷ FOSCCLK) + 9
For Example - For SYSCLK = 160MHz
Delay (in SYSCLK cycles) = 3 × (160MHz ÷ 8MHz) + 9 = 69 SYSCLK cycles
| Registers requiring delay after every write |
|---|
| PERCLKDIVSEL |
| SYSCLKDIVSEL |
| SYSPLLCTL |
| SYSPLLMULT |
| WDCR |
| XCLKOUTDIVSEL |
| XTALCR |
| CLKSRCCTL1 |
| CLKSRCCTL2 |
| CLKSRCCTL3 |
| CPU1TMR2CTL (TMR2CLKCTL) |