CM0 CM0+: interrupts disabled beween xTaskCreate() and vTaskStartScheduler()

On Cortex-M0 and Cortex-M0+, all IT are disabled between xTaskCreate() and
vTaskStartScheduler().
So it is not possible to use IT inbetween, like Serial.print() ...
This is the reason why, in example "frLiyLayland", between xTaskCreate()
and vTaskStartScheduler(),
we use direct printf(), which will access directly USART without interrupt

Signed-off-by: Alexandre Bourdiol <alexandre.bourdiol@st.com>

Author: ABOSTM

README.md

@@ -49,6 +49,10 @@ CMSIS-RTOSv2.
 
 * MPU: not supported.
 * No CMSIS-RTOSv2 support provided. It is provided as example.
+* On Cortex-M0 and Cortex-M0+, all IT are disabled between xTaskCreate() and vTaskStartScheduler().
+  So it is not possible to use IT inbetween, like Serial.print() ...
+  This is the reason why, in example "frLiyLayland", between xTaskCreate() and vTaskStartScheduler(),
+  we use direct printf(), which will access directly USART without interrupt
 
 ## Files & Configuration
 
@@ -109,8 +113,8 @@ CMSIS-RTOSv2.
 ### STM32FreeRTOS v10.3.1
 | Board | AnalogRead_DigitalRead | frBlinkPrint | frLiuLayland | frBlink (CMSIS-RTOSv2) | Blinky (CMSIS-RTOSv2) |
 | --- | :---: | :---: | :---: | :---: | :---: |
-| [Nucleo F091RC (Cortex-M0)](http://www.st.com/en/evaluation-tools/nucleo-f091rc.html) | PASSED | PASSED | FAILED | PASSED | PASSED |
-| [Nucleo G071RB (Cortex-M0+)](http://www.st.com/en/evaluation-tools/nucleo-g071rb.html) | PASSED | PASSED | FAILED | PASSED | PASSED |
+| [Nucleo F091RC (Cortex-M0)](http://www.st.com/en/evaluation-tools/nucleo-f091rc.html) | PASSED | PASSED | PASSED | PASSED | PASSED |
+| [Nucleo G071RB (Cortex-M0+)](http://www.st.com/en/evaluation-tools/nucleo-g071rb.html) | PASSED | PASSED | PASSED | PASSED | PASSED |
 | [Nucleo F103RB (Cortex-M3)](http://www.st.com/en/evaluation-tools/nucleo-f103rb.html) | PASSED | PASSED | PASSED | PASSED | PASSED |
 | [Nucleo L476RG (Cortex-M4)](http://www.st.com/en/evaluation-tools/nucleo-l476rg.html) | PASSED | PASSED | PASSED | PASSED | PASSED |
 | [Nucleo H743ZI (Cortex-M7)](https://www.st.com/en/evaluation-tools/nucleo-h743zi.html) | PASSED | PASSED | PASSED | PASSED | PASSED |

examples/frLiuLayland/frLiuLayland.ino

@@ -68,19 +68,22 @@ void calibrate() {
 }
 //------------------------------------------------------------------------------
 // print helpers
+// On Cortex-M0 and Cortex-M0+, all IT are disabled between xTaskCreate() and vTaskStartScheduler().
+// So it is not possible to use IT inbetween, like Serial.print() ...
+// This is the reason why, in example "frLiyLayland", between xTaskCreate() and vTaskStartScheduler(),
+// we use direct printf(), which will access directly USART without interrupt
 void printTask(task_t* task) {
-    Serial.print(task->period);
-    Serial.write(',');
-    Serial.print(task->cpu);
-    Serial.write(',');
-    Serial.println(task->priority);
+  printf("%u, ", task->period);
+  printf("%u, ", task->cpu);
+  printf("%u\r\n", task->priority);
 }
 void done(const char* msg, task_t* task, TickType_t now) {
   vTaskSuspendAll();
   Serial.println(msg);
   Serial.print("Tick: ");
   Serial.println(now);
   Serial.print("Task: ");
+  Serial.flush();
   printTask(task);
   while(1);
 }
@@ -152,21 +155,22 @@ void setup() {
   Serial.println(micros() -t);
   Serial.println("Starting tasks - period and CPU in ticks");
   Serial.println("Period,CPU,Priority");
+  Serial.flush();
   for (int i = 0; i < n; i++) {
     printTask(&tasks[i]);
     cpuUse += tasks[i].cpu/(float)tasks[i].period;
 
     s = xTaskCreate(task, NULL, 200, (void*)&tasks[i], tasks[i].priority, NULL);
     if (s != pdPASS) {
-      Serial.println("task create failed");
+      printf("task create failed\n");
       while(1);
     }
   }
-  Serial.print("CPU use %: ");
-  Serial.println(cpuUse*100);
-  Serial.print("Liu and Layland bound %: ");
-  Serial.println(LiuLayland[n - 1]);
 
+  char CPU[10];
+  char bound[10];
+  printf("CPU use %%: %s\r\n", dtostrf(cpuUse*100, 6,  2, CPU));
+  printf("Liu and Layland bound %%: %s\r\n", dtostrf(LiuLayland[n - 1], 6,  2, bound));
   // start tasks
   vTaskStartScheduler();
   Serial.println("Scheduler failed");