-#define START_GAP 50*8 // 10 - 50fc 250
-#define WRITE_GAP 20*8 // - 30fc 160
-#define WRITE_0 24*8 // 16 - 63fc 54fc 144
-#define WRITE_1 54*8 // 48 - 63fc 54fc 432 for T55x7; 448 for E5550 //400
+#define START_GAP 31*8 // was 250 // SPEC: 8 - 50fc [15fc]
+#define WRITE_GAP 20*8 // was 160 // SPEC: 8 - 20fc [10fc]
+#define WRITE_0 18*8 // was 144 // SPEC: 16 - 32fc [24fc] 192
+#define WRITE_1 50*8 // was 400 // SPEC: 48 - 64fc [56fc] 432 for T55x7; 448 for E5550
+
+// VALUES TAKEN FROM EM4x function: SendForward
+// START_GAP = 440; (55*8) cycles at 125Khz (8us = 1cycle)
+// WRITE_GAP = 128; (16*8)
+// WRITE_1 = 256 32*8; (32*8)
+
+// These timings work for 4469/4269/4305 (with the 55*8 above)
+// WRITE_0 = 23*8 , 9*8 SpinDelayUs(23*8);
+
+// Sam7s has several timers, we will use the source TIMER_CLOCK1 (aka AT91C_TC_CLKS_TIMER_DIV1_CLOCK)
+// TIMER_CLOCK1 = MCK/2, MCK is running at 48 MHz, Timer is running at 48/2 = 24 MHz
+// Hitag units (T0) have duration of 8 microseconds (us), which is 1/125000 per second (carrier)
+// T0 = TIMER_CLOCK1 / 125000 = 192
+// 1 Cycle = 8 microseconds(us)