UT to measure rms noise on ADC ports

git-svn-id: https://svn.code.sf.net/p/freetel/code@1823 01035d8c-6547-0410-b346-abe4f91aad63

diff --git a/codec2-dev/stm32/src/adc_sd.c b/codec2-dev/stm32/src/adc_sd.c
new file mode 100644 (file)
index 0000000..91414d2
--- /dev/null
+++ b/codec2-dev/stm32/src/adc_sd.c
@@ -0,0 +1,75 @@
+/*---------------------------------------------------------------------------*\\r
+\r
+  FILE........: adc_sd.c\r
+  AUTHOR......: David Rowe\r
+  DATE CREATED: 30 May 2014\r
+\r
+  Measures the std deviation of the ADC signals.  Used to check noise\r
+  levels on each ADC.\r
+\r
+\*---------------------------------------------------------------------------*/\r
+\r
+/*\r
+  Copyright (C) 2014 David Rowe\r
+\r
+  All rights reserved.\r
+\r
+  This program is free software; you can redistribute it and/or modify\r
+  it under the terms of the GNU Lesser General Public License version 2.1, as\r
+  published by the Free Software Foundation.  This program is\r
+  distributed in the hope that it will be useful, but WITHOUT ANY\r
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or\r
+  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public\r
+  License for more details.\r
+\r
+  You should have received a copy of the GNU Lesser General Public License\r
+  along with this program; if not, see <http://www.gnu.org/licenses/>.\r
+*/\r
+\r
+#include <stdlib.h>\r
+#include <math.h>\r
+#include "stm32f4_adc.h"\r
+#include "stm32f4_dac.h"\r
+#include "gdb_stdio.h"\r
+\r
+#define REC_TIME_SECS 10\r
+#define  N  (ADC_BUF_SZ*4)\r
+#define FS  16000\r
+\r
+static float calc_sd(short x[], int n) {\r
+    float sum, mean, sum_diff, sd;\r
+    int   i;\r
+\r
+    sum = 0.0;\r
+    for(i=0; i<n;i++) {\r
+        sum += (float)x[i];\r
+    }\r
+    mean = sum/n;\r
+\r
+    sum_diff = 0.0;\r
+    for(i=0; i<n;i++) {\r
+        sum_diff += ((float)x[i] - mean)*((float)x[i] - mean);\r
+    }\r
+    \r
+    sd = sqrtf(sum_diff/n);\r
+\r
+    return sd;\r
+}\r
+\r
+int main(void){\r
+    short  buf[N];\r
+    float  sd1, sd2;\r
+\r
+    adc_open(2*N);\r
+\r
+    printf("Starting!\n");\r
+    while(1) {\r
+        while(adc1_read(buf, N) == -1);\r
+        sd1 = calc_sd(buf, N);\r
+        while(adc2_read(buf, N) == -1);\r
+        sd2 = calc_sd(buf, N);\r
+\r
+        printf("adc1: %5.1f adc2: %5.1f\n", (double)sd1, (double)sd2);\r
+    }\r
+\r
+}\r