Moved AN00246 from xCORE-200 to xCORE.ai MC Audio Board

examples/shared/apppll.h

@@ -0,0 +1,108 @@
+
+#include <stdint.h>
+#include "xassert.h"
+
+// App PLL setup
+#define APP_PLL_CTL_BYPASS       (0)   // 0 = no bypass, 1 = bypass.
+#define APP_PLL_CTL_INPUT_SEL    (0)   // 0 = XTAL, 1 = sysPLL
+#define APP_PLL_CTL_ENABLE       (1)   // 0 = disabled, 1 = enabled.
+
+// 24MHz in, 24.576MHz out, integer mode
+// Found exact solution:   IN  24000000.0, OUT  24576000.0, VCO 2457600000.0, RD  5, FD  512, OD 10, FOD  10
+#define APP_PLL_CTL_OD_48        (4)   // Output divider = (OD+1)
+#define APP_PLL_CTL_F_48         (511) // FB divider = (F+1)/2
+#define APP_PLL_CTL_R_48         (4)   // Ref divider = (R+1)
+
+#define APP_PLL_CTL_48           ((APP_PLL_CTL_BYPASS << 29) | (APP_PLL_CTL_INPUT_SEL << 28) | (APP_PLL_CTL_ENABLE << 27) |\
+                                    (APP_PLL_CTL_OD_48 << 23) | (APP_PLL_CTL_F_48 << 8) | APP_PLL_CTL_R_48)
+
+// Fractional divide is M/N
+#define APP_PLL_FRAC_EN_48             (0)   // 0 = disabled
+#define APP_PLL_FRAC_NPLUS1_CYCLES_48  (0)   // M value is this reg value + 1.
+#define APP_PLL_FRAC_TOTAL_CYCLES_48   (0)   // N value is this reg value + 1.
+#define APP_PLL_FRAC_48          ((APP_PLL_FRAC_EN_48 << 31) | (APP_PLL_FRAC_NPLUS1_CYCLES_48 << 8) | APP_PLL_FRAC_TOTAL_CYCLES_48)
+
+// 24MHz in, 22.5792MHz out (44.1kHz * 512), frac mode
+// Found exact solution:   IN  24000000.0, OUT  22579200.0, VCO 2257920000.0, RD  5, FD  470.400 (m =   2, n =   5), OD  5, FOD   10
+#define APP_PLL_CTL_OD_441       (4)   // Output divider = (OD+1)
+#define APP_PLL_CTL_F_441        (469) // FB divider = (F+1)/2
+#define APP_PLL_CTL_R_441        (4)   // Ref divider = (R+1)
+
+#define APP_PLL_CTL_441          ((APP_PLL_CTL_BYPASS << 29) | (APP_PLL_CTL_INPUT_SEL << 28) | (APP_PLL_CTL_ENABLE << 27) |\
+                                    (APP_PLL_CTL_OD_441 << 23) | (APP_PLL_CTL_F_441 << 8) | APP_PLL_CTL_R_441)
+
+#define APP_PLL_FRAC_EN_44             (1)   // 1 = enabled
+#define APP_PLL_FRAC_NPLUS1_CYCLES_44  (1)   // M value is this reg value + 1.
+#define APP_PLL_FRAC_TOTAL_CYCLES_44   (4)   // N value is this reg value + 1.define APP_PLL_CTL_R_441        (4)   // Ref divider = (R+1)
+#define APP_PLL_FRAC_44   ((APP_PLL_FRAC_EN_44 << 31) | (APP_PLL_FRAC_NPLUS1_CYCLES_44 << 8) | APP_PLL_FRAC_TOTAL_CYCLES_44)
+
+#define APP_PLL_DIV_INPUT_SEL    (1)   // 0 = sysPLL, 1 = app_PLL
+#define APP_PLL_DIV_DISABLE      (0)   // 1 = disabled (pin connected to X1D11), 0 = enabled divider output to pin.
+#define APP_PLL_DIV_VALUE        (4)   // Divide by N+1 - remember there's a /2 also afterwards for 50/50 duty cycle.
+#define APP_PLL_DIV              ((APP_PLL_DIV_INPUT_SEL << 31) | (APP_PLL_DIV_DISABLE << 16) | APP_PLL_DIV_VALUE)
+
+/* TODO support more than two freqs..*/
+void AppPllEnable(int32_t clkFreq_hz)
+{
+    switch(clkFreq_hz)
+    {
+        case 44100*512:
+
+            // Disable the PLL
+            write_node_config_reg(tile[1], XS1_SSWITCH_SS_APP_PLL_CTL_NUM, (APP_PLL_CTL_441 & 0xF7FFFFFF));
+            // Enable the PLL to invoke a reset on the appPLL.
+            write_node_config_reg(tile[1], XS1_SSWITCH_SS_APP_PLL_CTL_NUM, APP_PLL_CTL_441);
+            // Must write the CTL register twice so that the F and R divider values are captured using a running clock.
+            write_node_config_reg(tile[1], XS1_SSWITCH_SS_APP_PLL_CTL_NUM, APP_PLL_CTL_441);
+            // Now disable and re-enable the PLL so we get the full 5us reset time with the correct F and R values.
+            write_node_config_reg(tile[1], XS1_SSWITCH_SS_APP_PLL_CTL_NUM, (APP_PLL_CTL_441 & 0xF7FFFFFF));
+            write_node_config_reg(tile[1], XS1_SSWITCH_SS_APP_PLL_CTL_NUM, APP_PLL_CTL_441);
+
+            // Set the fractional divider if used
+            write_node_config_reg(tile[0], XS1_SSWITCH_SS_APP_PLL_FRAC_N_DIVIDER_NUM, APP_PLL_FRAC_44);
+
+            break;
+
+        case 48000*512:
+
+            // Disable the PLL
+            write_node_config_reg(tile[1], XS1_SSWITCH_SS_APP_PLL_CTL_NUM, (APP_PLL_CTL_48 & 0xF7FFFFFF));
+            // Enable the PLL to invoke a reset on the appPLL.
+            write_node_config_reg(tile[1], XS1_SSWITCH_SS_APP_PLL_CTL_NUM, APP_PLL_CTL_48);
+            // Must write the CTL register twice so that the F and R divider values are captured using a running clock.
+            write_node_config_reg(tile[1], XS1_SSWITCH_SS_APP_PLL_CTL_NUM, APP_PLL_CTL_48);
+            // Now disable and re-enable the PLL so we get the full 5us reset time with the correct F and R values.
+            write_node_config_reg(tile[1], XS1_SSWITCH_SS_APP_PLL_CTL_NUM, (APP_PLL_CTL_48 & 0xF7FFFFFF));
+            write_node_config_reg(tile[1], XS1_SSWITCH_SS_APP_PLL_CTL_NUM, APP_PLL_CTL_48);
+
+            // Set the fractional divider if used
+            write_node_config_reg(tile[0], XS1_SSWITCH_SS_APP_PLL_FRAC_N_DIVIDER_NUM, APP_PLL_FRAC_48);
+
+            break;
+
+        default:
+            assert(0);
+            break;
+    }
+
+    // Wait for PLL output frequency to stabilise due to fractional divider enable
+    delay_microseconds(100);
+
+    // Turn on the clock output
+    write_node_config_reg(tile[0], XS1_SSWITCH_SS_APP_CLK_DIVIDER_NUM, APP_PLL_DIV);
+}
+
+void AppPllEnable_SampleRate(int32_t sampleRate_hz)
+{
+    assert(sampleRate_hz >= 22050);
+
+    if(sampleRate_hz % 22050 == 0)
+    {
+        AppPllEnable(44100*512);
+    }
+    else
+    {
+        AppPllEnable(48000*512);
+    }
+}
+