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--- dig:mic-servo [2011/03/22 14:41] – tobi
+++ dig:mic-servo [2011/03/23 11:10] – tobi
@@ Line 1: / Line 1: @@
-Here are the main.c and mic-servo.py code for a working project for [[lab_3]].
+Here are the main.c and mic-servo.py code for a working project for [[lab_3]].  You can download the AVR32 project (the device side) as {{dig:mic-servo.zip|mic-servo.zip}}.
 ==== main.c ====
@@ Line 62: / Line 62: @@
 #  define EXAMPLE_TC_IRQ_GROUP        AVR32_TC_IRQ_GROUP
 #  define EXAMPLE_TC_IRQ              AVR32_TC_IRQ0
-#  define FPBA                        FOSC0 // chosen PBA clock frequency - set up to be same as cystral freq=12MHz
 #define FADC 10000 // desired ADC sample rate in Hz
 #define TC_CHANNEL    0
@@ Line 104: / Line 103: @@
 #define FOSC0           12000000                              //!< Osc0 frequency: Hz.
+#define FPBA			(FOSC0*11/2/2)	// from power manager clock setup = 33MHz
 #define OSC0_STARTUP    AVR32_PM_OSCCTRL0_STARTUP_2048_RCOSC  //!< Osc0 startup time: RCOsc periods.
 void init_clock() {
@@ Line 456: / Line 457: @@
 	  .burst    = FALSE,                             // Burst signal selection.
 	  .clki     = FALSE,                             // Clock inversion.
-	  .tcclks   = TC_CLOCK_SOURCE_TC2                // Internal source clock 2, connected to fPBA/2=6MHz.
+	  .tcclks   = TC_CLOCK_SOURCE_TC2                // Internal source clock 2, connected to fPBA/2=15.5MHz.
 	};
@@ Line 485: / Line 486: @@
 	// Set the compare triggers for timer/counter (TC).
-	// TC counter is 16-bits, with secondary main clock fPBA = 12 MHz.
+	// TC counter is 16-bits, with secondary main clock TIMER_CLOCK2 = FPBA clock/2  = 33 MHz/2=15.5MHz.
-	// Lowest possible freq is 12e6/2^16=183.1Hz.
+	// Lowest possible freq is 15.5MHz/(2^16)=236Hz.
 	// We want ADC sample rate of FADC Hz.  To get this, we load RC (Reset Counter) value so that
-	// TC reaches RC value every 1/FADC ms. Therefore we configure TC so that RC=FPBA/FADC.
+	// TC reaches RC value every 1/FADC s. Therefore we configure TC so that RC=FPBA/FADC.
-	// E.g., to get FADC=10kHz, we need RC=12e6/10000=1200.
+	// E.g., to get FADC=10kHz, we need RC=15.5MHz/10000=1550.
+	// The timer interrupt will then run at 10kHz (verfied on scope).
+	// The timer interrupt for debug will toggle PA10 which will result in a square wave at 5kHz (verified).
 	tc_write_rc(tc, TC_CHANNEL, (FPBA /2) / FADC); // Set RC value.