init

lib_sw_pll/examples/shared/src/clock_gen.c

@@ -0,0 +1,60 @@
+// Copyright 2023 XMOS LIMITED.
+// This Software is subject to the terms of the XMOS Public Licence: Version 1.
+
+#include <xs1.h>
+#include <stdio.h>
+#include <xcore/hwtimer.h>
+#include <xcore/port.h>
+
+#include "sw_pll_common.h"
+
+#define DO_CLOCKS \
+printf("Ref Hz: %d\n", clock_rate >> 1); \
+\
+unsigned cycle_ticks_int = XS1_TIMER_HZ / clock_rate; \
+unsigned cycle_ticks_remaidner = XS1_TIMER_HZ % clock_rate; \
+unsigned carry = 0; \
+\
+period_trig += XS1_TIMER_HZ * 1; \
+unsigned time_now = hwtimer_get_time(period_tmr); \
+while(TIMER_TIMEAFTER(period_trig, time_now)) \
+{ \
+    port_out(p_clock_gen, port_val); \
+    hwtimer_wait_until(clock_tmr, time_trig); \
+    time_trig += cycle_ticks_int; \
+    carry += cycle_ticks_remaidner; \
+    if(carry >= clock_rate){ \
+        time_trig++; \
+        carry -= clock_rate; \
+    } \
+    port_val ^= 1; \
+    time_now = hwtimer_get_time(period_tmr); \
+}
+
+void clock_gen(unsigned ref_frequency, unsigned ppm_range) // Step from - to + this
+{
+    unsigned clock_rate = ref_frequency * 2; // Note double because we generate edges at this rate
+
+    unsigned clock_rate_low = (unsigned)(clock_rate * (1.0 - (float)ppm_range / 1000000.0));
+    unsigned clock_rate_high = (unsigned)(clock_rate * (1.0 + (float)ppm_range / 1000000.0));
+    unsigned step_size = (clock_rate_high - clock_rate_low) / 20;
+
+    printf("Sweep range: %d %d %d, step size: %d\n", clock_rate_low / 2, clock_rate / 2, clock_rate_high / 2, step_size);
+
+    hwtimer_t period_tmr = hwtimer_alloc();
+    unsigned period_trig = hwtimer_get_time(period_tmr);
+
+    hwtimer_t clock_tmr = hwtimer_alloc();
+    unsigned time_trig = hwtimer_get_time(clock_tmr);
+
+    port_t p_clock_gen = PORT_I2S_BCLK;
+    port_enable(p_clock_gen);
+    unsigned port_val = 1;
+
+    for(unsigned clock_rate = clock_rate_low; clock_rate <= clock_rate_high; clock_rate += 2 * step_size){
+        DO_CLOCKS
+    }
+    for(unsigned clock_rate = clock_rate_high; clock_rate > clock_rate_low; clock_rate -= 2 * step_size){
+        DO_CLOCKS
+    }
+}