Fix SDRAM timing setup during initialization#457
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We now compute them from the datasheet constants. Specifically, in procedure Initialize: * ExitSelfRefreshDelay, SelfRefreshTime, and RowCycleDelay were all derived from a single SDRAM_Min_Delay_In_ns constant, collapsing three distinct timing constraints (TXSR, TRAS, TRC) into one value. SelfRefreshTime was also hardcoded to 4 cycles, valid only at 90 MHz SDCLK. * Replace with per-parameter ceiling division over named board constants (SDRAM_TXSR_In_Ns, SDRAM_TRAS_In_Ns, SDRAM_TRC_In_Ns) so each constraint is satisfied independently at any clock frequency. STM32.Board spec: * add new SDRAM constants for the sake of the SDRAM initialization
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@jklmnn The change to stm32-board.ads doesn't seem to be taken into account by the CI builder, so as a result the change to stm32-sdram.adb fails. |
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F429/F469/F769 previously had a single SDRAM_Min_Delay_In_ns; replace with the same SDRAM_TRAS_In_Ns / SDRAM_TRC_In_Ns / SDRAM_TXSR_In_Ns trio that the shared SDRAM driver expects. F746 comment block reworked to cite the actual on-board part (Micron MT48LC4M32B2B5-6A) and the ST BSP source; tXSR corrected from 70 to 67 to match the Micron datasheet.
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| SDRAM_TRAS_In_Ns : constant := 42; -- TRAS | ||
| SDRAM_TRC_In_Ns : constant := 70; -- TRC |
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These two lines have trailing spaces. Removing these should fix the CI.
Bump copyright year to 2026 on F429/F469/F769 stm32-board.ads Companion to the SDRAM timing edits in this PR; F746 was already at 2026.
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stm32-sdram.adb:
We now compute initialization values from the datasheet constants. Specifically, in procedure Initialize:
ExitSelfRefreshDelay, SelfRefreshTime, and RowCycleDelay were all derived from a single SDRAM_Min_Delay_In_ns constant, improperly collapsing three distinct timing constraints (TXSR, TRAS, TRC) into one value.
SelfRefreshTime was also hardcoded to 4 cycles, valid only at 90 MHz SDCLK.
We replace those with per-parameter ceiling division over named board constants (SDRAM_TXSR_In_Ns, SDRAM_TRAS_In_Ns, SDRAM_TRC_In_Ns) so each constraint is satisfied independently at any clock frequency.
stm32-board.ads: