STM32H7S3L8H6: max fCPU with AXI-SRAM ECC enabled (DS14359 Rev 6, Table 26, footnote 8)

[PaulB_1]

Device: STM32H7S3L8H6

Datasheet DS14359 Rev 6, Table 26 "General operating conditions", gives for
fCPU (CPU clock frequency):

    VOS low    max 400 MHz
    VOS high   max 600 MHz   (8)
    footnote (8): "With ECC disabled"

We cannot find any stated maximum for fCPU with the AXI-SRAM ECC ENABLED
(user option byte ECC_ON_SRAM = 1). RM0477 mentions ECC only in connection
with AXISRAM4 wait states, not with a frequency limit.

This matters to us because ST's own OEMuRoT/BL2 reference code
(OEMIROT_USER_SRAM_ECC in boot_hal_cfg.h) requires that option byte and
refuses to boot without it, so an application using the STiRoT + OEMuRoT
secure boot chain necessarily runs with ECC permanently enabled.

Operating conditions on our side: VOS high (range 0), LDO supply,
TJ <= 105 degC.

Questions:

1. What is the maximum fCPU for this device with ECC_ON_SRAM = 1?

2. In the OEMuRoT reference code, SetSysClock() selects 380 MHz with the
   comment "to be functional with all hardware configurations (ECC_ON_SRAM
   enabled, no internal regulator) and with the full range of temperature
   (Tj up to 125 degrees)". Is 380 MHz the ECC-enabled limit, or is it the
   intersection of several worst cases? If the latter, what limit applies
   for ECC enabled at VOS high with TJ <= 105 degC?

[mƎALLEm]

Hello,

I’m asking that question internally: max fCPU frequency for ECC enabled. Internet ticket number for follow-up CDM0065413 (not accessible by the community users).

I’ll get back to you when I have an answer or asking question.

 

[mƎALLEm]

Having a confirmation from the team,

The Max CPU frequency with ECC enabled is 400MHz at VOS high.

The datasheet will be updated accordingly.

PS: in next time please avoid asking the same question over both channels: OLS and Community. Please choose one channel at a time.

Thank you for your understanding.

[novaksta]

Hello ​@PaulB_1 ,

 

the maximum CPU frequency with ECC enabled in VOS High is 400 MHz. The “General operating conditions” table in the datasheet will be updated in next revision with the maximum frequency values when ECC is enabled and disabled.