X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=bertos%2Fcpu%2Farm%2Fhw%2Finit_at91.c;h=1bba1c223e044aaceecb5ebe4570b7ecef5cc186;hb=e444d916197e4345dd2bbd85800d8544c2699096;hp=9c3eeb208c92fc03ff5062490598e8de25928dfb;hpb=5e046ad751e05b325e5337bd26b22e340ac8ad67;p=bertos.git

diff --git a/bertos/cpu/arm/hw/init_at91.c b/bertos/cpu/arm/hw/init_at91.c
index 9c3eeb20..1bba1c22 100644
--- a/bertos/cpu/arm/hw/init_at91.c
+++ b/bertos/cpu/arm/hw/init_at91.c
@@ -150,8 +150,22 @@ void __init2(void);
  */
 void __init1(void)
 {
-	/* Use 2 cycles for flash access. */
-	MC_FMR = MC_FWS_2R3W;
+	/*
+	 * Compute number of master clock cycles in 1.5us.
+	 * Needed by flash writing functions.
+	 * The maximum FMCN value is 0xFF and 0 can be used only if
+	 * master clock is less than 33kHz.
+	 */
+	#define MCN  DIV_ROUNDUP(CPU_FREQ, 666667UL)
+	#define FMCN (CPU_FREQ <= 33333UL ? 0 : (MCN < 0xFF ? MCN : 0xFF))
+
+	#if CPU_FREQ < 30000000UL
+		/* Use 1 cycles for flash access. */
+		MC_FMR = FMCN << MC_FMCN_SHIFT | MC_FWS_1R2W;
+	#else
+		/* Use 2 cycles for flash access. */
+		MC_FMR = FMCN << MC_FMCN_SHIFT | MC_FWS_2R3W;
+	#endif
 
         /* Disable all interrupts. Useful for debugging w/o target reset. */
 	AIC_EOICR = 0xFFFFFFFF;