Texas Instruments OMAP36 Series, Technical Reference Manual

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PRCM Use Cases and Tips
3.7.1.3.2 Switch VDD1 OPPs
1. Switch from VDD1 OPP130 to VDD1 OPP100, assuming that
• OPP130 (VDD1 = v2, (MPU_CLK = f
mpu
2, IVA2_CLK = f
iva
2))
• OPP100 (VDD1 = v1, (MPU_CLK = f
mpu
1, IVA2_CLK = f
iva
1))
and v2 > v1 , f
mpu
2 > f
mpu
1, f
iva
2 > f
iva
1.
To switch from OPP130 to OPP100, the processor frequencies must be reduced before switching the
voltage. The DPLL1 and DPLL2 frequencies are scaled by changing the multiplier and divider values.
The DPLLs must relock, and they switch to bypass mode. DPLL frequency (F
DPLL
) is calculated as:
F
DPLL
= (SYS_CLK*2*M)/(N+1)
If SYS_CLK is 38.4 MHz, the values of M and N can be:
PRCM. CM_CLKSEL1_PLL_MPU [18:8] MPU_DPLL_MULT - The multiplier and divider of DPLL1 are configured for
OPP100 frequency.
PRCM. CM_CLKSEL1_PLL_MPU [6:0] MPU_DPLL_DIV -
PRCM. CM_CLKSEL1_PLL_IVA2 [18:8] IVA2_DPLL_MULT - The multiplier and divider of DPLL2 are configured for
OPP50 frequency.
PRCM. CM_CLKSEL1_PLL_IVA2 [6:0] IVA2_DPLL_DIV -
The SmartReflex1 and voltage processor1 modules are disabled for voltage scaling.
SR1. SRCONFIG [11] SR_EN 0x0 Disable the SmartReflex1 module.
PRCM. PRM_VP1_CONFIG [0] VPENABLE 0x0 Disable the voltage processor1 module.
The parameters of the error generator in the SmartReflex1 module are configured corresponding to
OPP100.
SR1. NVALUERECIPROCAL [23:20] SENPGAIN Configured according to the settings in eFuse
SR1. NVALUERECIPROCAL [19:16] SENNGAIN See Section 3.5.6.5.4.5 , Parameter Configuration.
SR1. NVALUERECIPROCAL [15:8] RNSENP
SR1. NVALUERECIPROCAL [7:0] RNSENN
SR1. SRCONFIG [9] ERRORGENERATORENABLE 0x1 Enable the error generator.
The OPP change-done interrupt of voltage processor1 and the voltage processor bounds interrupt of
the SmartReflex1 module are enabled. The remaining interrupts of the voltage processor and
SmartReflex modules can be masked.
SR1. ERRCONFIG [22] VPBOUNDSINTENABLE 0x1 Enable the SmartReflex1 voltage processor interrupt.
PRCM. PRM_IRQENABLE_MPU 0x1 Enable the VP1 OPP change-done interrupt.
VP1_OPPCHANGEDONE_EN
The voltage processor1 and SmartReflex1 modules are enabled.
PRCM. PRM_VP1_CONFIG [0] VPENABLE 0x1 Enable the voltage processor1 module.
SR1. SRCONFIG [11] SR_EN 0x1 Enable the SmartReflex1 module.
The SmartReflex1 module sends the OPP change-done interrupt when the OPP change is complete
and the voltage is stable.
PRCM. PRM_IRQSTATUS_MPU [10] VP1_ Read On read, if this bit is 0x1, the OPP change is complete.
OPPCHANGEDONE_ST
PRCM. PRM_IRQSTATUS_MPU [10] VP1_ 0x1 Writing 0x1 clears the interrupt status bit.
OPPCHANGEDONE_ST
Enable the voltage processor1 interrupt for automatic SmartReflex1 operation.
SR1. ERRCONFIG [22] VPBOUNDSINTENABLE 0x1 Enable the voltage processor bounds Interrupt.
2. Switch from VDD1 OPP100 to VDD1 OPP130, assuming that
• OPP130 (VDD1 = v2, (MPU_CLK = f
mpu
2, IVA2_CLK = f
iva
2))
• OPP100 (VDD1 = v1, (MPU_CLK = f
mpu
1, IVA2_CLK = f
iva
1))
and v2 > v1, f
mpu
2 > f
mpu
1, f
iva
2 > f
iva
1.
To switch from OPP100 to OPPTM, the domain voltage must be switched before the frequency
453 SWPU177N – December 2009 – Revised November 2010 Power, Reset, and Clock Management
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