diff options
Diffstat (limited to 'nuttx/configs/open1788/src/lpc17_sdraminitialize.c')
| -rw-r--r-- | nuttx/configs/open1788/src/lpc17_sdraminitialize.c | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/nuttx/configs/open1788/src/lpc17_sdraminitialize.c b/nuttx/configs/open1788/src/lpc17_sdraminitialize.c index e18643f20..10196b18c 100644 --- a/nuttx/configs/open1788/src/lpc17_sdraminitialize.c +++ b/nuttx/configs/open1788/src/lpc17_sdraminitialize.c @@ -62,15 +62,18 @@ * * For example: * LPC17_CCLCK = 120,000,000 - * EMCCLKSEL -> use LPC17_CCLK undivided - * LPC17_EMCCLK = 120,000,000 - * LPC17_EMCCLK_MHZ = 120 (rounded) - * EMC_NSPERCLK = 8 (rounded) + * EMCCLKSEL -> LPC17_CCLK divided by 2 + * LPC17_EMCCLK = 60,000,000 + * LPC17_EMCCLK_MHZ = 60 (Rounded to an integer) + * EMC_NSPERCLK = 16.667 (Represented with 4 bits of fraction, 267) + * + * EMC_NS2CLK(63) = ((63 << 4) + 266) / 267 = 4 (actual 3.78) + * EMC_NS2CLK(20) = ((20 << 4) + 266) / 267 = 2 (actual 1.20) */ #define LPC17_EMCCLK_MHZ ((LPC17_EMCCLK + 500000) / 1000000) -#define EMC_NSPERCLK ((1000 + (LPC17_EMCCLK_MHZ >> 1)) / LPC17_EMCCLK_MHZ) -#define EMC_NS2CLK(ns) ((ns + (EMC_NSPERCLK - 1)) / EMC_NSPERCLK) +#define EMC_NSPERCLK_B4 (((1000 << 4) + (LPC17_EMCCLK_MHZ >> 1)) / LPC17_EMCCLK_MHZ) +#define EMC_NS2CLK(ns) (((ns << 4) + (EMC_NSPERCLK_B4 - 1)) / EMC_NSPERCLK_B4) #define MDKCFG_RASCAS0VAL 0x00000303 /* Set up for 32-bit SDRAM at CS0 */ |