Revision 0:76eeca7a361f, committed 2018-01-28
- Comitter:
- wavejumper
- Date:
- Sun Jan 28 12:38:34 2018 +0000
- Commit message:
- FIR_Filter mixed-c/asm (not working yet)
Changed in this revision
diff -r 000000000000 -r 76eeca7a361f main.cpp
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Sun Jan 28 12:38:34 2018 +0000
@@ -0,0 +1,90 @@
+#include "mbed.h"
+
+/*LPF cut off frequency 600Hz(3rd Order with 20kHz sampling frequency)*/
+AnalogIn Ain(p15);
+AnalogOut Aout(p18);
+
+float data_in,data_out;
+
+Ticker s1_khz_tick;
+
+__ASM int addi(int a, int b)
+{
+ ADDS R0, R1
+ BX LR
+}
+
+__ASM int multi(int a, int b)
+{
+ MUL R0, R1
+ BX LR
+}
+
+__ASM int move(int a, int b)
+{
+ MOV R0, R1
+ BX LR
+}
+
+float LPF(float LPF_in)
+{
+
+ //------------------------------FIR ----------------------------------------------------
+ float fda_coeff[16] = {0.00028360651120682420830293457569837301,
+ 0.00822761997979659653879025427158921957,
+ 0.009652502067820697279065811358123028185,
+ -0.020505027860776389725394608376518590376,
+ -0.055082214281865632399259880003228317946,
+ 0.001759656378417649713608028605449362658,
+ 0.187202210776797661750947554537560790777,
+ 0.369320487034980882157242376706562936306,
+ 0.369320487034980882157242376706562936306,
+ 0.187202210776797661750947554537560790777,
+ 0.001759656378417649713608028605449362658,
+ -0.055082214281865632399259880003228317946,
+ -0.020505027860776389725394608376518590376,
+ 0.009652502067820697279065811358123028185,
+ 0.00822761997979659653879025427158921957,
+ 0.00028360651120682420830293457569837301
+ };
+
+ static float LPF_out; //the return variable/outbput of filter
+ static float x[12], y, z[12];
+
+ for (int i = 10; i >= 0; i--) {
+ x[i+1] = move(x[i+1], x[i]);
+ }
+
+ x[0] = move(x[0], LPF_in);
+
+ for (int i = 0; i < 12; i++) {
+ z[i] = multi(fda_coeff[i], x[i]);
+ }
+
+ for (int i = 0; i < 12; i++) {
+ y = addi(z[i], y);
+ }
+
+ LPF_out = move(LPF_out, y);
+ return LPF_out; //output filtered value
+}
+
+void s1khz_task(void)
+{
+ data_in = Ain - 0.5; //Note the embed can only accept positive voltage inputs, it is necessary to add a small coupling and biasing circuit to
+ //offset the signal midway of approx 1.65V.
+ //A DC offset is a frequency component at 0 Hz. This can cause signal to wander.
+ //Therefore the mean value of the signal is subtracted.This is also to normalize the signal to an average value of zero,
+ //and allows the filter algorithm to perform DSP with no DC offset in the data.
+
+ data_out = LPF(data_in);
+ Aout = data_out + 0.5;
+}
+
+int main()
+{
+ s1_khz_tick.attach_us(&s1khz_task,1000); //1kHz sampling
+
+ while(1);
+
+}
\ No newline at end of file
diff -r 000000000000 -r 76eeca7a361f mbed.bld
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld Sun Jan 28 12:38:34 2018 +0000
@@ -0,0 +1,1 @@
+https://os.mbed.com/users/mbed_official/code/mbed/builds/7130f322cb7e
\ No newline at end of file