From 281c0f68d5c4bdf955d4cefceb4de6d0e0321363 Mon Sep 17 00:00:00 2001
From: Andy Killorin <37423245+Speedy6451@users.noreply.github.com>
Date: Sat, 12 Apr 2025 18:40:26 -0400
Subject: [PATCH] calculate cpu usage with a hardware timer

had to bump the display stack size to keep snprintf from crashing
---
 main.c   | 33 +++++++++++++++++++++++++++++++--
 rtos.cfg |  4 ++--
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/main.c b/main.c
index 5982e95..a59aac4 100644
--- a/main.c
+++ b/main.c
@@ -36,6 +36,8 @@ uint32_t gSystemClock = 120000000; // [Hz] system clock frequency
 
 tContext sContext;
 
+uint32_t cputime_unloaded;
+
 #define LOCAL_BUF_LEN 128
 uint16_t adc_buffer_sample[LOCAL_BUF_LEN]; // copy of g adc buffer
 uint8_t adc_buffer_processed[LOCAL_BUF_LEN]; // copy of g adc buffer
@@ -100,6 +102,26 @@ void start_signal() {
   PWMGenEnable(PWM0_BASE, PWM_GEN_1);
 }
 
+uint32_t cpu_load_count(void)
+{
+    uint32_t i = 0;
+    TimerIntClear(TIMER1_BASE, TIMER_TIMA_TIMEOUT);
+    TimerEnable(TIMER1_BASE, TIMER_A); // start one-shot timer
+    while (!(TimerIntStatus(TIMER1_BASE, false) & TIMER_TIMA_TIMEOUT))
+        i++;
+    return i;
+}
+
+void start_cputimer() {
+    // initialize timer 1 in one-shot mode for polled timing
+    SysCtlPeripheralEnable(SYSCTL_PERIPH_TIMER1);
+    TimerDisable(TIMER1_BASE, TIMER_BOTH);
+    TimerConfigure(TIMER1_BASE, TIMER_CFG_ONE_SHOT);
+    TimerLoadSet(TIMER1_BASE, TIMER_A, gSystemClock/100); // 10ms interval
+    // baseline load
+    cputime_unloaded = cpu_load_count();
+}
+
 /*
  *  ======== main ========
  */
@@ -111,6 +133,7 @@ int main(void)
     start_signal();
     start_sampler();
     ButtonInit();
+    start_cputimer();
 
     Crystalfontz128x128_Init(); // Initialize the LCD display driver
     Crystalfontz128x128_SetOrientation(LCD_ORIENTATION_UP); // set screen orientation
@@ -215,6 +238,12 @@ void display_waveform(UArg arg1, UArg arg2)
     while(1) {
         Semaphore_pend(display_sem, BIOS_WAIT_FOREVER);
 
+        // calculate cpu usage
+        uint32_t cputime_loaded;
+        cputime_loaded = cpu_load_count();
+        float usage_percent;
+        usage_percent = (1.0 - (float) cputime_loaded / (float) cputime_unloaded) * (float) 100.;
+
         GrContextForegroundSet(&sContext, ClrBlack);
         GrRectFill(&sContext, &rectFullScreen); // fill screen with black
 
@@ -235,8 +264,8 @@ void display_waveform(UArg arg1, UArg arg2)
         GrContextForegroundSet(&sContext, ClrWheat);
         GrStringDraw(&sContext, gVoltageScaleStr[voltage_scale], /*length*/ -1, /*x*/ 0, /*y*/ 0, /*opaque*/ false);
         GrStringDraw(&sContext, gTimeScaleStr[time_scale], /*length*/ -1, /*x*/ 60, /*y*/ 0, /*opaque*/ false);
-        //snprintf(str, sizeof(str), "CPU Load %.1f%%", usage_percent);
-        //GrStringDraw(&sContext, str, /*length*/ -1, /*x*/ 0, /*y*/ HEIGHT - 10, /*opaque*/ false);
+        snprintf(str, sizeof(str), "CPU Load %.1f%%", usage_percent);
+        GrStringDraw(&sContext, str, /*length*/ -1, /*x*/ 0, /*y*/ HEIGHT - 10, /*opaque*/ false);
 
         switch (trigger_mode) {
             case 1:
diff --git a/rtos.cfg b/rtos.cfg
index e9cb9ab..6f06a7a 100644
--- a/rtos.cfg
+++ b/rtos.cfg
@@ -567,7 +567,7 @@ Program.global.processing = Task.create("&process_waveform", task2Params);
 var task3Params = new Task.Params();
 task3Params.instance.name = "display";
 task3Params.priority = 5;
-task3Params.stackSize = 1024;
+task3Params.stackSize = 2048;
 Program.global.display = Task.create("&display_waveform", task3Params);
 var semaphore2Params0 = new Semaphore.Params();
 semaphore2Params0.instance.name = "display_sem";
@@ -591,5 +591,5 @@ mailbox0Params.instance.name = "button_mailbox";
 Program.global.button_mailbox = Mailbox.create(1, 9, mailbox0Params);
 var task5Params = new Task.Params();
 task5Params.instance.name = "user_input";
-task5Params.priority = 4;
+task5Params.priority = 6;
 Program.global.user_input = Task.create("&handle_user_input", task5Params);