[Prototyping] Reading CPU cycles from CYCCNT

We can read the number of CPU cycles, sleep cycles, ld/str waits, etc.
Uses STM32F4's, rarely documented DWT.

Further, various "backports" from main firmware to prototyping.

prototyping/pixracer/src/config/config.ads

@@ -12,5 +12,6 @@ package Config is
 
    MAIN_TICK_RATE_MS : constant := 10;   -- Tickrate in Milliseconds
 
+   With_SD_Log : constant Boolean := False;
 
 end Config;

prototyping/pixracer/src/driver/cpu.adb

@@ -5,18 +5,26 @@ with HIL.GPIO;
 with HIL.Clock;
 with HIL.SPI;
 with HIL.UART;
+with HIL.I2C;
+with HIL.Random;
+with Ada.Real_Time; use Ada.Real_Time;
 
-package body CPU is
+
+package body CPU with SPARK_Mode is
 
    --  configures hardware registers
    procedure initialize is
+      startup_time : constant Ada.Real_Time.Time := Ada.Real_Time.Clock;
    begin
       --  Configure GPIO
       HIL.Clock.configure;
-      HIL.GPIO.configure;
+      HIL.Random.initialize;
       HIL.UART.configure;
+      HIL.GPIO.configure;
       HIL.SPI.configure;
       --  HIL.I2C.initialize;
+      delay until startup_time + Ada.Real_Time.Milliseconds (200);
+      HIL.I2C.initialize;
 
    end initialize;
 

prototyping/pixracer/src/main.adb

@@ -13,18 +13,19 @@ with LED_Manager;
 with Buzzer_Manager;
 with SDLog;
 with ULog;
+with STM32.DWT;
 
 package body Main is
 
-   ENDL : constant String := (Character'Val (13), Character'Val (10));
-
    procedure Initialize is
       success : Boolean := False;
       t_next  : Ada.Real_Time.Time;
       logret  : Logger.Init_Error_Code;
    begin
       CPU.initialize;
 
+      STM32.DWT.Enable_Cycle_Counter;
+
       Logger.init (logret);
       Logger.log_console (Logger.INFO, "---------------");
       Logger.log_console (Logger.INFO, "CPU initialized");
@@ -40,8 +41,12 @@ package body Main is
       Logger.log_console (Logger.INFO, "Initializing NVRAM...");
       NVRAM.Init;
 
-      Logger.log_console (Logger.INFO, "Start SD Logging...");
-      Logger.Start_SDLog;
+      if With_SD_Log then
+         Logger.log_console (Logger.INFO, "Start SD Logging...");
+         Logger.Start_SDLog;
+      else
+         Logger.log_console (Logger.INFO, "SD Log disabled in config.");
+      end if;
 
       --  self checks
       Logger.log_console (Logger.INFO, "Self-Check NVRAM...");
@@ -72,18 +77,25 @@ package body Main is
 
 
    procedure Run_Loop is
-      --  data    : HIL.SPI.Data_Type (1 .. 3)  := (others => 0);
-      --  data_rx : HIL.UART.Data_Type (1 .. 1) := (others => 0);
-      loop_time_start   : Time      := Clock;
+      loop_period : constant Time_Span := Milliseconds (MAIN_TICK_RATE_MS);
+      loop_next   : Time      := Clock;
 
       --      gleich : Ada.Real_Time.Time;
       --      song : constant Buzzer_Manager.Song_Type := (('c',6),('d',6),('c',6),('f',6));
-      type prescaler is mod 100;
-      p : prescaler := 0;
+      PRESCALER : constant := 100;
+      type prescaler_t is mod PRESCALER;
+      p : prescaler_t := 0;
 
       type prescaler_gps is mod 20;
       pg : prescaler_gps := 0;
       mgps : ULog.Message (ULog.GPS);
+
+      --  loop measurements
+      cycle_begin : Unsigned_32;
+      cycles_sum  : Unsigned_32 := 0;
+      cycles_avg  : Unsigned_32;
+      cycles_min  : Unsigned_32 := Unsigned_32'Last;
+      cycles_max  : Unsigned_32 := Unsigned_32'First;
    begin
       LED_Manager.Set_Color ((HIL.Devices.RED_LED => False, HIL.Devices.GRN_LED => True, HIL.Devices.BLU_LED => False));
       LED_Manager.LED_blink (LED_Manager.SLOW);
@@ -105,33 +117,62 @@ package body Main is
       mgps.lat := 48.15;
       mgps.lon := 11.583;
       mgps.alt := 560.0;
-      mgps.gps_week := 1908;
-      mgps.gps_msec := 0;
+      mgps.gps_year := 1908;
+      mgps.gps_month := 1;
+      mgps.gps_sec := 0;
       mgps.fix := 0;
       mgps.nsat := 8;
 
       loop
-         loop_time_start := Clock;
+         cycle_begin := STM32.DWT.Read_Cycle_Counter;
 
          p := p + 1;
-         if p = 0 then
-            Logger.log_console (Logger.INFO, "Logfile size " & SDLog.Logsize'Img & " B");
-         end if;
-
-         pg := pg + 1;
-         if pg = 0 then
-            mgps.t := Ada.Real_Time.Clock;
-            mgps.lat := mgps.lat - 0.1;
-            mgps.gps_msec := mgps.gps_msec + 100;
-            Logger.log_sd (msg_level => Logger.SENSOR, message => mgps);
+         if With_SD_Log then
+            if p = 0 then
+               Logger.log_console (Logger.INFO, "Logfile size " & SDLog.Logsize'Img & " B");
+            end if;
+
+            --  fake GPS message to test SD log
+            pg := pg + 1;
+            if pg = 0 then
+               mgps.t := Ada.Real_Time.Clock;
+               mgps.lat := mgps.lat - 0.1;
+               mgps.gps_sec := mgps.gps_sec + 1;
+
+               Logger.log_sd (msg_level => Logger.SENSOR, message => mgps);
+            end if;
          end if;
 
          --  LED heartbeat
          LED_Manager.LED_tick (MAIN_TICK_RATE_MS);
          LED_Manager.LED_sync;
 
+         declare
+            cycle_end   : constant Unsigned_32 := STM32.DWT.Read_Cycle_Counter;
+            cycles_loop : constant Unsigned_32 := cycle_end - cycle_begin;
+         begin
+            cycles_sum := cycles_sum + cycles_loop;
+            cycles_min := (if cycles_loop < cycles_min then cycles_loop else cycles_min);
+            cycles_max := (if cycles_loop > cycles_max then cycles_loop else cycles_max);
+
+            if p = 0 then
+               --  output
+               cycles_avg := cycles_sum / PRESCALER;
+               logger.log_console
+                 (Logger.INFO, "Loop min/avg/max cyc: " &
+                    Unsigned_32'Image(cycles_min) &
+                    Unsigned_32'Image(cycles_avg) &
+                    Unsigned_32'Image(cycles_max));
+               --  reset
+               cycles_sum := 0;
+               cycles_min := Unsigned_32'Last;
+               cycles_max := Unsigned_32'First;
+            end if;
+         end;
+
          --  wait remaining loop time
-         delay until loop_time_start + Milliseconds (MAIN_TICK_RATE_MS);
+         loop_next := loop_next + loop_period;
+         delay until loop_next;
       end loop;
    end Run_Loop;