Texas Instruments OMAP36 Series, Техническое справочное руководство

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PRCM Basic Programming Model
When switching from OPPx to OPPy so the clock frequency at OPPx is higher than the clock frequency at
OPPy, the DPLL is first switched to the lower frequency of OPPy and only voltage scaling is initiated (see
Figure 3-99 a). However, if the clock frequency of OPPx is less than the frequency of OPPy, voltage
scaling is initiated before the frequency scaling (see Figure 3-99 b).
OPP voltage switching complete is detected by the OPPCHANGEDONE interrupt from the voltage
processor to the MPU. For this, the corresponding MPU interrupt must be unmasked.
NOTE: In the following steps, VPn refers to VP1 if VDD1 OPP is changed, and to VP2 if VDD2
OPP is changed.
1. Disable the modules.
To configure the parameters of the SmartReflex module, both the SmartReflex and voltage processor
modules are disabled. This ensures that no voltage command is passed to the SMPS while the OPP
change is being configured.
SRn. SRCONFIG [11] SR_EN 0x0 Disable the SmartReflex module.
PRCM.PRM_VPn_CONFIG[0] VPENABLE 0x0 Disable the voltage processor module.
2. Configure settings for OPPy.
Setting the error generator consists of setting its parameters according to the target OPP, and then
enabling the error-generator block. These values are configured according to the target operating
performance point of the device.
SRn. NVALUERECIPROCAL [23:20] SENPGAIN Configured according to the current OPP values read for the
SCM register
SRn. NVALUERECIPROCAL [19:16] SENNGAIN See Section 3.5.6.5.4.5 , Parameter Configuration.
SRn. NVALUERECIPROCAL [15:8] RNSENP
SRn. NVALUERECIPROCAL [7:0] RNSENN
SRn. SRCONFIG [9] ERRORGENERATORENABLE 0x1 Enable the error generator.
3. Set SmartReflex and voltage processor interrupts.
To automatically adjust the voltage from OPPx level to OPPy level, the voltage processor interrupt
from the SmartReflex module to the voltage processor module must be is unmasked. Similarly, to
detect completion of the switch to OPPy, the OPP change-done interrupt from the voltage processor to
the MPU must be unmasked.
This is especially important when switching to a higher-frequency operating point, because the voltage
must be stable before the frequency is switched.
The remaining SmartReflex and voltage processor interrupts can be masked.
SmartReflex interrupt setting:
SRn. ERRCONFIG [22] VPBOUNDSINTENABLE 0x1 Enable the VP bounds interrupt.
Voltage processor interrupt setting:
PRCM. PRM_IRQENABLE_MPU 0x1 Enable the VPn OPP change-done interrupt.
VPn_OPPCHANGEDONE_EN
NOTE: After reset, all interrupts are masked.
4. Enable the modules.
The voltage processor is enabled first, and then the SmartReflex module is enabled. The SmartReflex
module counters start counting the pulses, and the error-generator logic is active. The module
generates the error to the voltage processor module to send the voltage command to SMPS. The
voltage is thus adjusted according to OPPy.
443 SWPU177N – December 2009 – Revised November 2010 Power, Reset, and Clock Management
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