ST / ST_I2S

STMicroelectronics' implementation of an I2S driver, also including DMA support.

Dependents:   temp X_NUCLEO_CCA01M1 X_NUCLEO_CCA01M1 X_NUCLEO_CCA02M1

Platform compatibility

This driver has been designed to support a wide range of the Nucleo F4 Family of platforms and MCUs, but not all members of this family support I2S and/or some of the members might require slight modifications to the sources of this driver in order to make it work on those.

This driver has for now been tested only with the following platforms:

Diff: targets/TARGET_STM/stm_i2s_api.c

Revision:
12:7309748f058a
Parent:
10:1a612c2e4a85
Child:
13:fa1b24df9025
--- a/targets/TARGET_STM/stm_i2s_api.c	Thu Dec 22 14:39:28 2016 +0100
+++ b/targets/TARGET_STM/stm_i2s_api.c	Thu Dec 22 15:00:34 2016 +0100
@@ -896,6 +896,7 @@
     return f;
 }
 
+// betzw - QUESTION: seems to resolve only the case of multiples of 2!?!
 int8_t i2s_harmonize(i2s_t *dev_i2s_1, uint32_t *freq_i2s_1, i2s_t *dev_i2s_2, uint32_t *freq_i2s_2)
 {
     /* Compute the real frequencies. */
@@ -917,14 +918,16 @@
         q = f2 / f1;
     else
         q = f1 / f2;
-    float r = q - (uint32_t) q;
-
+    float r = q - (uint32_t) q; /* betzw - TODO: call libc functions to get a guarantee 
+				   for actually desired behavior */
+						 
     if (r > 0)
     {
         if (f1 < f2)
         {
             float mf = i2s_compute_magic_factor(dev_i2s_1, f2 / 2);
-            r = mf - (uint32_t) mf;
+            r = mf - (uint32_t) mf; /* betzw - TODO: call libc functions to get a guarantee 
+				       for actually desired behavior */
             if (r > 0)
             {
                 if (f2 > *freq_i2s_2)
@@ -939,7 +942,8 @@
         else
         {
             float mf = i2s_compute_magic_factor(dev_i2s_2, f1 / 2);
-            r = mf - (uint32_t) mf;
+            r = mf - (uint32_t) mf; /* betzw - TODO: call libc functions to get a guarantee 
+				       for actually desired behavior */
             if (r > 0)
             {
                 if (f1 > *freq_i2s_1)
@@ -951,6 +955,8 @@
             else
                 f2 = f1 / 2;
         }
+    } else { // betzw - QUESTION for Davide!
+	return -1;
     }
 
     //printf("DESIRED: %f %f\r\n", f1, f2);