ChibiOS 2.6.8, until I can figure out where to get it from git.

firmware/chibios/boards/OLIMEX_LPC_P2148/buzzer.c

@@ -0,0 +1,111 @@
+/*
+    ChibiOS/RT - Copyright (C) 2006-2013 Giovanni Di Sirio
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+        http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+*/
+
+/*
+ * Buzzer driver for Olimex LPC-P2148.
+ * Uses the timer 1 for wave generation and a Virtual Timer for the sound
+ * duration.
+ * The driver also generates an event when the sound is done and the buzzer
+ * goes silent.
+ */
+
+#include "ch.h"
+#include "hal.h"
+
+#include "buzzer.h"
+
+EventSource BuzzerSilentEventSource;
+
+#define StartCounter(t) ((t)->TC_EMR = 0xF1, (t)->TC_TCR = 1)
+#define StopCounter(t)  ((t)->TC_EMR = 0, (t)->TC_TCR = 2)
+
+/**
+ * @brief Buzzer driver initialization.
+ */
+void buzzInit(void) {
+
+  chEvtInit(&BuzzerSilentEventSource);
+
+  /*
+   * Switches P0.12 and P0.13 to MAT1.0 and MAT1.1 functions.
+   * Enables Timer1 clock.
+   */
+  PINSEL0 &= 0xF0FFFFFF;
+  PINSEL0 |= 0x0A000000;
+  PCONP = (PCONP & PCALL) | PCTIM1;
+
+  /*
+   * Timer setup.
+   */
+  TC *tc = T1Base;
+  StopCounter(tc);
+  tc->TC_CTCR = 0;                      /* Clock source is PCLK.        */
+  tc->TC_PR   = 0;                      /* Prescaler disabled.          */
+  tc->TC_MCR  = 2;                      /* Clear TC on match MR0.       */
+}
+
+/**
+ * @brief Stops the sound.
+ *
+ * @param[in] p pointer to the timer
+ */
+static void stop(void *p) {
+
+  StopCounter((TC *)p);
+  chSysLockFromIsr();
+  chEvtBroadcastI(&BuzzerSilentEventSource);
+  chSysUnlockFromIsr();
+}
+
+/**
+ * @brief Plays a tone asynchronously.
+ *
+ * @param[in] freq approximated tone frequency
+ * @param[in] duration tone duration in systicks
+ */
+void buzzPlay(uint32_t freq, systime_t duration) {
+  static VirtualTimer bvt;
+  TC *tc = T1Base;
+
+  chSysLock();
+
+  if (chVTIsArmedI(&bvt)) {             /* If a sound is already being  */
+    chVTResetI(&bvt);                   /* played then aborts it.       */
+    StopCounter(tc);
+  }
+
+  tc->TC_MR0 = tc->TC_MR1 = (PCLK / (freq * 2));
+  StartCounter(tc);
+  chVTSetI(&bvt, duration, stop, tc);
+
+  chSysUnlock();
+}
+
+/**
+ * @brief Plays a tone.
+ *
+ * @param[in] freq approximated tone frequency
+ * @param[in] duration tone duration in systicks
+ */
+void buzzPlayWait(uint32_t freq, systime_t duration) {
+  TC *tc = T1Base;
+
+  StopCounter(tc);
+  tc->TC_MR0 = tc->TC_MR1 = (PCLK / (freq * 2));
+  StartCounter(tc);
+  chThdSleep(duration);
+  StopCounter(tc);
+}