Amador Valley High School Robotics Team
This is a small program we use to see how long something takes. It runs the code in the while loop a lot of times and prints out how many us it took. Then this can be divided by the number of iterations to find the time/clock cycles for each iteration.
Diff: main.cpp
- Revision:
- 0:cff63309a8af
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Mon Jul 08 03:58:56 2013 +0000
@@ -0,0 +1,26 @@
+#include "mbed.h"
+#include "dsp.h"
+
+Serial pc(USBTX, USBRX);
+DigitalOut myled(LED1);
+Timer tim;
+
+int main() {
+ unsigned int i = 0;
+
+ q15_t lad[5], ref[6];
+ q15_t state[1029], in[1024], out[1024];
+ // this loop takes 4 assembly instructions to run per cycle
+ // http://www.wolframalpha.com/input/?i=%282731+us%2F65536%29%2F%281%2F24000000Hz%29
+ arm_iir_lattice_instance_q15 filter = {5, state, ref, lad};
+ tim.start();
+ while (i<100)
+ {
+ arm_iir_lattice_q15(&filter, in, out, 1024);
+ i++;
+ }
+ tim.stop();
+ pc.printf("%d us\n\r",tim.read_us());
+}
+//mbed LPC1768 runs at 96 MHz
+//2731 us=65536 cycles
\ No newline at end of file