[修改] 增加freeRTOS

1. 版本FreeRTOSv202212.01，命名为kernel；

kernel/FreeRTOS/Demo/PIC32MX_MPLAB/timertest.c

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+/*
+ * FreeRTOS V202212.01
+ * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * https://www.FreeRTOS.org
+ * https://github.com/FreeRTOS
+ *
+ */
+
+/* High speed timer test as described in main.c. */
+
+
+/* Scheduler includes. */
+#include "FreeRTOS.h"
+
+/* The maximum value the 16bit timer can contain. */
+#define timerMAX_COUNT				0xffff
+
+/* The timer 2 interrupt handler.  As this interrupt uses the FreeRTOS assembly
+entry point the IPL setting in the following function prototype has no effect.
+The interrupt priority is set by ConfigIntTimer2() in vSetupTimerTest(). */
+void __attribute__( (interrupt(IPL0AUTO), vector(_TIMER_2_VECTOR))) vT2InterruptWrapper( void );
+
+/*-----------------------------------------------------------*/
+
+/* Incremented every 20,000 interrupts, so should count in seconds. */
+unsigned long ulHighFrequencyTimerInterrupts = 0;
+
+/* The frequency at which the timer is interrupting. */
+static unsigned long ulFrequencyHz;
+
+/*-----------------------------------------------------------*/
+
+void vSetupTimerTest( unsigned short usFrequencyHz )
+{
+	/* Remember the frequency so it can be used from the ISR. */
+	ulFrequencyHz = ( unsigned long ) usFrequencyHz;
+
+	/* T2 is used to generate interrupts above the kernel and max syscall interrupt
+	priority. */
+	T2CON = 0;
+	TMR2 = 0;
+
+	/* Timer 2 is going to interrupt at usFrequencyHz Hz. */
+	PR2 = ( unsigned short ) ( ( configPERIPHERAL_CLOCK_HZ / ( unsigned long ) usFrequencyHz ) - 1 );
+
+	/* Setup timer 2 interrupt priority to be above the kernel priority so
+	the timer jitter is not effected by the kernel activity. */
+	IPC2bits.T2IP = ( configMAX_SYSCALL_INTERRUPT_PRIORITY + 1 );
+
+	/* Clear the interrupt as a starting condition. */
+	IFS0bits.T2IF = 0;
+
+	/* Enable the interrupt. */
+	IEC0bits.T2IE = 1;
+
+	/* Start the timer. */
+	T2CONbits.TON = 1;
+}
+/*-----------------------------------------------------------*/
+
+void vT2InterruptHandler( void )
+{
+static unsigned long ulCalls = 0;
+
+	++ulCalls;
+	if( ulCalls >= ulFrequencyHz )
+	{
+		/* Increment the count that will be shown on the LCD.
+		The increment occurs once every 20,000 interrupts so
+		ulHighFrequencyTimerInterrupts should count in seconds. */
+		ulHighFrequencyTimerInterrupts++;
+		ulCalls = 0;
+	}
+
+	/* Clear the timer interrupt. */
+	IFS0CLR = _IFS0_T2IF_MASK;
+}
+
+