initial

.gitignore

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+*.o
+firmware.txt
+firmware.elf
+firmware.map
+

Makefile

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+TOOLCHAIN_PREFIX=/opt/msp430-gcc
+CC=$(TOOLCHAIN_PREFIX)/bin/msp430-elf-gcc
+OBJDUMP=$(TOOLCHAIN_PREFIX)/bin/msp430-elf-objdump
+
+ARTIFACT=firmware
+MCU=msp430g2553
+DEBUGFLAGS=
+DEBUGFLAGS+= -g3 -ggdb -gdwarf-2
+COMMONFLAGS=-Wall -mmcu=$(MCU) -I $(TOOLCHAIN_PREFIX)/include -O0 -g0 $(DEBUGFLAGS)
+CFLAGS=$(COMMONFLAGS) -std=gnu99 
+ASFLAGS=$(COMMONFLAGS) -D__ASSEMBLER__
+
+LDFLAGS=-mmcu=$(MCU) -L $(TOOLCHAIN_PREFIX)/include
+
+$(ARTIFACT).elf:	main.o scheduler.o
+	$(CC) -o $@ $(LDFLAGS) $^
+	$(OBJDUMP) -D $(ARTIFACT).elf > $(ARTIFACT).txt
+
+.c.o:	
+	$(CC) $(CFLAGS) -c $<
+
+.S.o:	
+	$(CC) $(ASFLAGS) -c $<
+
+
+.PHONY: all
+all:	$(ARTIFACT).elf
+
+.PHONY: clean
+clean:
+	-rm -f *.o $(ARTIFACT).elf $(ARTIFACT).txt
+
+.PHONY: upload
+upload: $(ARTIFACT).elf
+	mspdebug rf2500 "prog $(ARTIFACT).elf"

firmware.gdb

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+target remote localhost:2000
+file firmware.elf

main.c

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+#include <msp430g2553.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "scheduler.h"
+
+int main() {
+  WDTCTL = WDTPW | WDTHOLD;
+
+  __disable_interrupt();
+
+  // highest possible system clock
+  DCOCTL = DCO0 | DCO1 | DCO2;
+  BCSCTL1 = XT2OFF | RSEL0 | RSEL1 | RSEL2 | RSEL3;
+  BCSCTL2 = 0;
+  BCSCTL3 = 0;
+
+
+  schInit();
+
+
+
+  __enable_interrupt();
+
+
+  while (1) {
+    schExec();
+  }
+}

scheduler.c

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+#include <stdlib.h>
+#include <msp430g2553.h>
+#include "scheduler.h"
+
+tTask tasks[MAX_NUM_OF_TASKS];
+
+
+uint32_t seconds;
+
+void schInit() {
+  TACCR0 = 19600;
+  TACCTL0 = CCIE;
+  TACTL = MC_1 | ID_0 | TASSEL_2 | TACLR;
+
+  for (uint16_t i = 0; i < MAX_NUM_OF_TASKS; i++) {
+    tasks[i].delay = 0;
+    tasks[i].period = 0;
+    tasks[i].run = 0;
+    tasks[i].exec = NULL;
+    tasks[i].handle = NULL;
+  }
+
+  seconds = 0;
+
+  // LED
+  P2DIR |= BIT6;
+  P2OUT &= ~BIT6;
+  P2SEL &= ~BIT6;
+  P2SEL2 &= ~BIT6;
+}
+
+void __attribute__ ((interrupt (TIMER0_A0_VECTOR))) schUpdate() {
+  static uint16_t milliSeconds = 0;
+  if (milliSeconds >= 1000) {
+    seconds += 1;
+    milliSeconds = 0;
+    P2OUT ^= BIT6;
+  }
+  milliSeconds += 1;
+
+  for (uint16_t i = 0; i < MAX_NUM_OF_TASKS; i++) {
+    if (tasks[i].exec != NULL) {
+      if (tasks[i].delay == 0) {
+        tasks[i].delay = tasks[i].period;
+        tasks[i].run++;
+      } else {
+        tasks[i].delay--;
+      }
+    }
+  }
+}
+
+uint16_t schAdd(void (*exec)(void *), void *handle, uint32_t delay, uint32_t period) {
+  uint16_t taskId = 0xffff;
+  for (uint16_t i = 0; i < MAX_NUM_OF_TASKS; i++) {
+    if (tasks[i].exec == NULL) {
+      tasks[i].delay = delay;
+      tasks[i].period = period;
+      if (delay == 0 && period == 0) {
+        tasks[i].run = 1;
+      } else {
+        tasks[i].run = 0;
+      }
+      tasks[i].exec = exec;
+      tasks[i].handle = handle;
+      taskId = i;
+      break;
+    }
+  }
+  return taskId;
+}
+
+void schDel(uint16_t taskId) {
+  tasks[taskId].exec = NULL;
+}
+
+void schExec() {
+  for (uint16_t i = 0; i < MAX_NUM_OF_TASKS; i++) {
+    // synchronize access to tasks[].run
+    __disable_interrupt(); 
+    if (tasks[i].exec != NULL && tasks[i].run > 0) {
+      tasks[i].run--;
+      // synchronize access to tasks[].run
+      // reenable interrupts before actually executing task
+      __enable_interrupt();
+      tasks[i].exec(tasks[i].handle);
+      if (tasks[i].period == 0) {
+        tasks[i].exec = NULL;
+      }
+    } else {
+      // synchronize access to tasks[].run
+      // reenable interrupts in case task is not yet executable
+      __enable_interrupt();
+    }
+  }
+}
+
+uint32_t getSeconds() {
+  uint32_t s;
+
+  __disable_interrupt();
+  s = seconds;
+  __enable_interrupt();
+
+  return s;
+}
+

scheduler.h

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+#ifndef PONTCOOPSCHEDULER_H_
+#define PONTCOOPSCHEDULER_H_
+
+
+#include <stdint.h>
+
+
+
+#define MAX_NUM_OF_TASKS 4
+
+
+typedef struct {
+  uint16_t delay;
+  uint16_t period;
+  uint8_t run;
+  void (*exec)(void *handle);
+  void *handle;
+} tTask;
+
+
+void schInit();
+uint16_t schAdd(void (*exec)(void *), void *handle, uint32_t delay, uint32_t period);
+void schDel(uint16_t taskId);
+void schExec();
+
+
+#endif /* PONTCOOPSCHEDULER_H_ */