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Diffstat (limited to 'peripherals/tc/tc.c')
| -rw-r--r-- | peripherals/tc/tc.c | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/peripherals/tc/tc.c b/peripherals/tc/tc.c new file mode 100644 index 0000000..8a2b5af --- /dev/null +++ b/peripherals/tc/tc.c @@ -0,0 +1,144 @@ +/* ----------------------------------------------------------------------------
+ * ATMEL Microcontroller Software Support
+ * ----------------------------------------------------------------------------
+ * Copyright (c) 2008, Atmel Corporation
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the disclaimer below.
+ *
+ * Atmel's name may not be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
+ * DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
+ * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+ * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * ----------------------------------------------------------------------------
+ */
+
+//------------------------------------------------------------------------------
+// Headers
+//------------------------------------------------------------------------------
+
+#include "tc.h"
+
+//------------------------------------------------------------------------------
+// Global Functions
+//------------------------------------------------------------------------------
+
+//------------------------------------------------------------------------------
+/// Configures a Timer Counter to operate in the given mode. Timer is stopped
+/// after configuration and must be restarted with TC_Start(). All the
+/// interrupts of the timer are also disabled.
+/// \param pTc Pointer to an AT91S_TC instance.
+/// \param mode Operating mode (TC_CMR value).
+//------------------------------------------------------------------------------
+void TC_Configure(AT91S_TC *pTc, unsigned int mode)
+{
+ // Disable TC clock
+ pTc->TC_CCR = AT91C_TC_CLKDIS;
+
+ // Disable interrupts
+ pTc->TC_IDR = 0xFFFFFFFF;
+
+ // Clear status register
+ pTc->TC_SR;
+
+ // Set mode
+ pTc->TC_CMR = mode;
+}
+
+//------------------------------------------------------------------------------
+/// Enables the timer clock and performs a software reset to start the counting.
+/// \param pTc Pointer to an AT91S_TC instance.
+//------------------------------------------------------------------------------
+void TC_Start(AT91S_TC *pTc)
+{
+ pTc->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+}
+
+//------------------------------------------------------------------------------
+/// Disables the timer clock, stopping the counting.
+/// \param pTc Pointer to an AT91S_TC instance.
+//------------------------------------------------------------------------------
+void TC_Stop(AT91S_TC *pTc)
+{
+ pTc->TC_CCR = AT91C_TC_CLKDIS;
+}
+
+//------------------------------------------------------------------------------
+/// Finds the best MCK divisor given the timer frequency and MCK. The result
+/// is guaranteed to satisfy the following equation:
+/// \pre
+/// (MCK / (DIV * 65536)) <= freq <= (MCK / DIV)
+/// \endpre
+/// with DIV being the highest possible value.
+/// \param freq Desired timer frequency.
+/// \param mck Master clock frequency.
+/// \param div Divisor value.
+/// \param tcclks TCCLKS field value for divisor.
+/// \return 1 if a proper divisor has been found; otherwise 0.
+//------------------------------------------------------------------------------
+unsigned char TC_FindMckDivisor(
+ unsigned int freq,
+ unsigned int mck,
+ unsigned int *div,
+ unsigned int *tcclks)
+{
+ unsigned int index = 0;
+ unsigned int divisors[5] = {2, 8, 32, 128,
+#if defined(at91sam9260) || defined(at91sam9261) || defined(at91sam9g10) || defined(at91sam9263) \
+ || defined(at91sam9xe) || defined(at91sam9rl64) || defined(at91cap9) \
+ || defined(at91sam9m10) || defined(at91sam9g45) || defined(at91sam9m11) || defined(at91sam3u4)
+ 0};
+ divisors[4] = mck / 32768;
+#else
+ 1024};
+#endif
+
+ // Satisfy lower bound
+ while (freq < ((mck / divisors[index]) / 65536)) {
+
+ index++;
+
+ // If no divisor can be found, return 0
+ if (index == 5) {
+
+ return 0;
+ }
+ }
+
+ // Try to maximise DIV while satisfying upper bound
+ while (index < 4) {
+
+ if (freq > (mck / divisors[index + 1])) {
+
+ break;
+ }
+ index++;
+ }
+
+ // Store results
+ if (div) {
+
+ *div = divisors[index];
+ }
+ if (tcclks) {
+
+ *tcclks = index;
+ }
+
+ return 1;
+}
+
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