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ARM Cortex-A15 MPCore Processor Technical Reference Manual

ARM Cortex-A15 MPCore Processor Technical Reference Manual

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Functional DescriptionReset combination Signals Value DescriptionTable 2-2 Valid reset combinations (continued)NEON and VFP and Debug(PCLKDBG) resetnCPUPORESET [3:0]nCORERESET [3:0]nCXRESET [3:0]nDBGRESET [3:0]nPRESETDBGnL2RESET[n] = 1[n] = 1[n] = 0[n] = 101NEON and VFP and Debug (PCLKDBG) are held inreset, so that NEON and VFP and Debug(PCLKDBG) can be powered up.NEON and VFP and Debug (CLK)resetnCPUPORESET [3:0]nCORERESET [3:0]nCXRESET [3:0]nDBGRESET [3:0]nPRESETDBGnL2RESET[n] = 1[n] = 1[n] = 0[n] = 011NEON and VFP and Debug (CLK) are held in reset.Run mode nCPUPORESET [3:0]nCORERESET [3:0]nCXRESET [3:0]nDBGRESET [3:0]nPRESETDBGnL2RESET111111No logic is held in reset.a. For powerup reset or processor reset, nCPUPORESET must be asserted. The remaining processor resets, nCORERESET, nCXRESET,and nDBGRESET can be asserted, but is not required.b. For soft reset, nCORERESET must be asserted, nCXRESET can be asserted, but is not required.Note• nL2RESET resets the shared L2 memory system logic, GIC and Generic Timer that iscommon to all processors. This reset must not be asserted while any individual processoris active.• nPRESETDBG resets the shared Debug in PCLKDBG domain that is common to allprocessors. This reset must not be asserted while any individual processor is activelybeing debugged in normal operating mode or during external debug over power down.• If your implementation does not include the NEON and VFP unit, you can tie thenCXRESET input HIGH.There are specific requirements that you must meet to reset each reset domain listed in Table 2-1on page 2-12. Not adhering to these requirements can lead to a reset domain that is notfunctional.The reset sequences in the following sections are the only reset sequences that <strong>ARM</strong>recommends. Any deviation from these sequences might cause an improper reset of that resetdomain.The supported reset sequences are:• Powerup reset on page 2-16.• Soft reset on page 2-17.• NEON and VFP reset on page 2-18.• Debug PCLKDBG reset on page 2-19.• Memory arrays reset on page 2-19.<strong>ARM</strong> DDI 0438I Copyright © 2011-2013 <strong>ARM</strong>. All rights reserved. 2-15ID062913Non-Confidential

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