SPRUHM9H October 2014 – May 2024 TMS320F28075 , TMS320F28075-Q1 , TMS320F28076
For a given CPU subsystem, the CLA and DMA share secondary access to some peripherals. The secondary ownership of the bus is determined by the CpuSysRegs.SECMSEL[VBUS32_x] bit. If the bit is set to 0, the CLA is the secondary owner. If the bit is set to 1, the DMA is the secondary owner. By default, at reset, the CLA is given the secondary ownership of the bus and, therefore, can access all the peripherals connected to the bus.
Refer to the device data sheet for the list of peripherals connected to the bus.
Several peripheral control registers are protected from spurious 28x CPU writes by the EALLOW protection mechanism. These same registers are also protected from spurious CLA writes. The EALLOW bit in the CPU status register 1 (ST1) indicates the state of protection for the CPU. Likewise, the MEALLOW bit in the CLA status register (MSTF) indicates the state of write protection for the CLA. The MEALLOW CLA instruction enables write access by the CLA to EALLOW protected registers. Likewise, the MEDIS CLA instruction disables write access. This way the CLA can enable and disable write access independent of the CPU.
The ADC offers the option to generate an early interrupt pulse at the start of a sample conversion. If this option is used to start an ADC-triggered CLA task, use the intervening cycles until the completion of the conversion to perform preliminary calculations or loads and stores before finally reading the ADC value. The CLA pipeline activity for this scenario is shown in Section 6.5.