change PWM period with buttons

frequency.c

@@ -0,0 +1,77 @@
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "driverlib/sysctl.h"
+#include "driverlib/gpio.h"
+#include "driverlib/timer.h"
+#include "driverlib/pin_map.h"
+#include "inc/tm4c1294ncpdt.h"
+#include "driverlib/interrupt.h"
+#include "inc/hw_types.h"
+#include "inc/hw_memmap.h"
+#include "driverlib/fpu.h"
+#include <math.h>
+#include "driverlib/pwm.h"
+
+#include "frequency.h"
+
+// start a pwm test signal
+void start_signal() {
+  // configure M0PWM2, at GPIO PF2, BoosterPack 1 header C1 pin 2
+  SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);
+  GPIOPinTypePWM(GPIO_PORTF_BASE, GPIO_PIN_2 | GPIO_PIN_3);
+  GPIOPinConfigure(GPIO_PF2_M0PWM2);
+  GPIOPinConfigure(GPIO_PF3_M0PWM3);
+  GPIOPadConfigSet(GPIO_PORTF_BASE, GPIO_PIN_2 | GPIO_PIN_3, GPIO_STRENGTH_2MA,
+                   GPIO_PIN_TYPE_STD);
+  // configure the PWM0 peripheral, gen 1, outputs 2 and 3
+  SysCtlPeripheralEnable(SYSCTL_PERIPH_PWM0);
+  // use system clock without division
+  PWMClockSet(PWM0_BASE, PWM_SYSCLK_DIV_1);
+  PWMGenConfigure(PWM0_BASE, PWM_GEN_1,
+                  PWM_GEN_MODE_DOWN | PWM_GEN_MODE_NO_SYNC);
+  gPWMPeriod = roundf((float)gSystemClock / PWM_FREQUENCY);
+  set_pwm_period(gPWMPeriod);
+  PWMOutputState(PWM0_BASE, PWM_OUT_2_BIT | PWM_OUT_3_BIT, true);
+  PWMGenEnable(PWM0_BASE, PWM_GEN_1);
+}
+
+void set_pwm_period(uint32_t period) {
+    PWMGenPeriodSet(PWM0_BASE, PWM_GEN_1,
+                    gPWMPeriod);
+    PWMPulseWidthSet(PWM0_BASE, PWM_OUT_2,
+                     roundf((float)gPWMPeriod * 0.4f));
+    PWMPulseWidthSet(PWM0_BASE, PWM_OUT_3,
+                     roundf((float)gPWMPeriod * 0.4f));
+}
+
+
+
+void start_frequency_scan() {
+    // config GPIO PD0 as timer input T0CCP0 at BoosterPack Connector #1 pin 14
+    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOD);
+    GPIOPinTypeTimer(GPIO_PORTD_BASE, GPIO_PIN_0);
+    GPIOPinConfigure(GPIO_PD0_T0CCP0);
+    SysCtlPeripheralEnable(SYSCTL_PERIPH_TIMER0);
+    TimerDisable(TIMER0_BASE, TIMER_BOTH);
+    TimerConfigure(TIMER0_BASE, TIMER_CFG_SPLIT_PAIR | TIMER_CFG_A_CAP_TIME_UP);
+    TimerControlEvent(TIMER0_BASE, TIMER_A, TIMER_EVENT_POS_EDGE);
+    // use maximum load value
+    TimerLoadSet(TIMER0_BASE, TIMER_A, 0xffff);
+    // use maximum prescale value
+    TimerPrescaleSet(TIMER0_BASE, TIMER_A, 0xff);
+    TimerIntEnable(TIMER0_BASE, TIMER_CAPA_EVENT);
+    TimerEnable(TIMER0_BASE, TIMER_A);
+}
+
+uint32_t previous;
+void capture_handler() {
+    TimerIntClear(TIMER0_BASE, TIMER_CAPA_EVENT);
+
+    uint32_t current = TimerValueGet(TIMER0_BASE, TIMER_A);
+
+    uint32_t delta = current - previous;
+    gPeriod = delta;
+
+    previous = current;
+}

frequency.h

@@ -0,0 +1,12 @@
+#ifndef FREQUENCY_C
+#define FREQUENCY_C
+#define gSystemClock 120000000 // [Hz] system clock frequency
+
+#define PWM_FREQUENCY 20000 // PWM frequency = 20 kHz
+
+void start_frequency_scan(void);
+void set_pwm_period(uint32_t period);
+
+uint32_t gPeriod;
+uint32_t gPWMPeriod;
+#endif

main.c

@@ -31,12 +31,11 @@
 #include "driverlib/pin_map.h"
 #include "sampling.h"
 #include "buttons.h"
+#include "frequency.h"
 #include "kiss_fft.h"
 #include "_kiss_fft_guts.h"
 
-#define PWM_FREQUENCY 20000 // PWM frequency = 20 kHz
 
-uint32_t gSystemClock = 120000000; // [Hz] system clock frequency
 
 #define PI 3.14159265358979f
 
@@ -92,27 +91,7 @@ const float gVoltageScale[VOLTAGE_SCALES] = {
 
 int Trigger(bool rising);
 
-// start a pwm test signal
+
-void start_signal() {
-  // configure M0PWM2, at GPIO PF2, BoosterPack 1 header C1 pin 2
-  SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);
-  GPIOPinTypePWM(GPIO_PORTF_BASE, GPIO_PIN_2);
-  GPIOPinConfigure(GPIO_PF2_M0PWM2);
-  GPIOPadConfigSet(GPIO_PORTF_BASE, GPIO_PIN_2, GPIO_STRENGTH_2MA,
-                   GPIO_PIN_TYPE_STD);
-  // configure the PWM0 peripheral, gen 1, outputs 2 and 3
-  SysCtlPeripheralEnable(SYSCTL_PERIPH_PWM0);
-  // use system clock without division
-  PWMClockSet(PWM0_BASE, PWM_SYSCLK_DIV_1);
-  PWMGenConfigure(PWM0_BASE, PWM_GEN_1,
-                  PWM_GEN_MODE_DOWN | PWM_GEN_MODE_NO_SYNC);
-  PWMGenPeriodSet(PWM0_BASE, PWM_GEN_1,
-                  roundf((float)gSystemClock / PWM_FREQUENCY));
-  PWMPulseWidthSet(PWM0_BASE, PWM_OUT_2,
-                   roundf((float)gSystemClock / PWM_FREQUENCY * 0.4f));
-  PWMOutputState(PWM0_BASE, PWM_OUT_2_BIT, true);
-  PWMGenEnable(PWM0_BASE, PWM_GEN_1);
-}
 
 uint32_t cpu_load_count(void)
 {
@@ -146,6 +125,7 @@ int main(void)
     start_sampler();
     ButtonInit();
     start_cputimer();
+    start_frequency_scan();
 
     Crystalfontz128x128_Init(); // Initialize the LCD display driver
     Crystalfontz128x128_SetOrientation(LCD_ORIENTATION_UP); // set screen orientation
@@ -269,6 +249,12 @@ void handle_user_input() {
             case Down: // previous scale
                 local_options.voltage_scale = (local_options.voltage_scale + VOLTAGE_SCALES - 1) % VOLTAGE_SCALES;
                 break;
+            case SW1:
+                set_pwm_period(++gPWMPeriod);
+                break;
+            case SW2:
+                set_pwm_period(--gPWMPeriod);
+                break;
         }
 
         Semaphore_pend(options_sem, BIOS_WAIT_FOREVER);
@@ -315,7 +301,14 @@ void display_waveform(UArg arg1, UArg arg2)
         GrContextForegroundSet(&sContext, ClrWheat);
 
         snprintf(str, sizeof(str), "CPU Load %.1f%%", usage_percent);
+        GrStringDraw(&sContext, str, /*length*/ -1, /*x*/ 0, /*y*/ HEIGHT - 30, /*opaque*/ false);
+
+        uint32_t period = gPeriod;
+        float frequency = (float) gSystemClock / (float) period;
+        snprintf(str, sizeof(str), "f = %.1fhz", frequency);
         GrStringDraw(&sContext, str, /*length*/ -1, /*x*/ 0, /*y*/ HEIGHT - 10, /*opaque*/ false);
+        snprintf(str, sizeof(str), "T = %dc", period);
+        GrStringDraw(&sContext, str, /*length*/ -1, /*x*/ 0, /*y*/ HEIGHT - 20, /*opaque*/ false);
 
 
         if (local_options.fft) {

rtos.cfg

@@ -535,7 +535,7 @@ var driversConfig = xdc.useModule('ti.drivers.Config');
  *      Use TI-RTOS drivers library for debugging with asserts and logs enabled.
  */
 driversConfig.libType = driversConfig.LibType_NonInstrumented;
-Clock.timerId = 0;
+Clock.timerId = 2;
 TimestampProvider.useClockTimer = true;
 var m3Hwi0Params = new m3Hwi.Params();
 m3Hwi0Params.instance.name = "m3Hwi0";
@@ -597,3 +597,7 @@ Program.global.options_sem = Semaphore.create(1, semaphore4Params);
 var gateHwi0Params = new GateHwi.Params();
 gateHwi0Params.instance.name = "gateHwiDMA";
 Program.global.gateHwi0 = GateHwi.create(gateHwi0Params);
+var m3Hwi1Params = new m3Hwi.Params();
+m3Hwi1Params.instance.name = "m3Hwi1";
+m3Hwi1Params.priority = 4;
+Program.global.m3Hwi1 = m3Hwi.create(35, "&capture_handler", m3Hwi1Params);