LPC1788 and FLASHTIM value for 120MHz

giusloq — Tue, 19 Sep 2023 14:39:38 GMT

I want to run LPC1788 at 120MHz with IRC and PLL. From User Manual I read that I need to set PBOOST=3 and FLASHTIM=4 or 5. Of course, I can write:

Chip_SYSCTL_EnableBoost(); Chip_SYSCTL_SetFLASHAccess(4 or 5);

Those functions are defined as:

STATIC INLINE void Chip_SYSCTL_EnableBoost(void) { LPC_SYSCTL->PBOOST = 0x3; } STATIC INLINE void Chip_SYSCTL_SetFLASHAccess(FMC_FLASHTIM_T clks) { uint32_t tmp = LPC_SYSCTL->FLASHCFG & 0xFFF; /* Don't alter lower bits */ LPC_SYSCTL->FLASHCFG = tmp | (clks << 12); }

However LPCOpen defines FMC_FLASHTIM_T as:

typedef enum { FLASHTIM_20MHZ_CPU = 0, /*!< Flash accesses use 1 CPU clocks. Use for up to 20 MHz CPU clock */ FLASHTIM_40MHZ_CPU = 1, /*!< Flash accesses use 2 CPU clocks. Use for up to 40 MHz CPU clock */ FLASHTIM_60MHZ_CPU = 2, /*!< Flash accesses use 3 CPU clocks. Use for up to 60 MHz CPU clock */ FLASHTIM_80MHZ_CPU = 3, /*!< Flash accesses use 4 CPU clocks. Use for up to 80 MHz CPU clock */ FLASHTIM_100MHZ_CPU = 4, /*!< Flash accesses use 5 CPU clocks. Use for up to 100 MHz CPU clock */ #if defined(CHIP_LPC177X_8X) || defined(CHIP_LPC40XX) FLASHTIM_120MHZ_CPU = 3, /*!< Flash accesses use 4 CPU clocks. Use for up to 120 MHz CPU clock with power boot on*/ #else FLASHTIM_120MHZ_CPU = 4, /*!< Flash accesses use 5 CPU clocks. Use for up to 120 Mhz for LPC1759 and LPC1769 only.*/ #endif FLASHTIM_SAFE_SETTING = 5, /*!< Flash accesses use 6 CPU clocks. Safe setting for any allowed conditions */ } FMC_FLASHTIM_T;

It seems to me that definition of FLASHTIM_120MHZ_CPU is faulty, because it is defined as 3 for CHIP_LPC177X_8X and CHIP_LPC40XX, instead of 4.

What is the right value to set FLASHTIM for 120MHz and power boost?

Re: LPC1788 and FLASHTIM value for 120MHz

Alice_Yang — Wed, 20 Sep 2023 06:59:33 GMT

Hello @giusloq

Please follow the UM. As the UM mentioned, FLASHTIM should be 0100 for operation from 100 to 120 MHz operation with power boost on.

Alice

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LPC1788 and FLASHTIM value for 120MHz

Re: LPC1788 and FLASHTIM value for 120MHz