LPC2: add LPC2378 example project.

[bertos.git] / examples / lpc2378 / hw / hw_ntc.h

diff --git a/examples/lpc2378/hw/hw_ntc.h b/examples/lpc2378/hw/hw_ntc.h
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+/**
+ * \file
+ * <!--
+ * This file is part of BeRTOS.
+ *
+ * Bertos is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * As a special exception, you may use this file as part of a free software
+ * library without restriction.  Specifically, if other files instantiate
+ * templates or use macros or inline functions from this file, or you compile
+ * this file and link it with other files to produce an executable, this
+ * file does not by itself cause the resulting executable to be covered by
+ * the GNU General Public License.  This exception does not however
+ * invalidate any other reasons why the executable file might be covered by
+ * the GNU General Public License.
+ *
+ * Copyright 2008 Develer S.r.l. (http://www.develer.com/)
+ * All Rights Reserved.
+ * -->
+ *
+ * \brief NTC hardware-specific definition
+ *
+ * \version $Id: hw_ntc.h 1359 2008-05-26 09:42:37Z asterix $
+ * \author Francesco Sacchi <batt@develer.com>
+ *
+ * A NTC acts as a variable resistor, whose resistance changes as a
+ * function of the temperature it measures. To sample it correctly, it is
+ * usually parallelized and serialized with two fixed resistor. The following diagram shows
+ * what is the exact disposition of the components, as handled by this
+ * library:
+ *
+ *<pre>
+ *                 o Vref
+ *                 |
+ *                 |                               o Vref
+ *                 |                               |
+ *               -----                             |
+ *              |     |                        ---------
+ *              | Rser|                       |         |
+ *              |     |                       |         |
+ *               -----     -----              |   ADC   |
+ *                 | Vp   |     |             |         |
+ *      -----------|------| Amp |-------------|         |
+ *     |           |      |     |      Vadc   |         |
+ *   -----       -----     -----               ---------
+ *  |     |     |     |
+ *  | NTC |     | Rpar|
+ *  |     |     |     |
+ *   -----       -----
+ *     |           |
+ *     |           |
+ *   -----       -----
+ *    ---         ---
+ *</pre>
+ * Amp is an amplifier that amplify of AMP times the signal.
+ * If we indicate Rp as the parallel of NTC with Rpar, ADCBITS as the bits of the ad converter
+ * and ADCVAL as the result from the adc convertion (Not Vadc but just the value read
+ * from the adc register), after various calculation, the expression of Rp is:
+ *
+ *<pre>
+ *
+ *            ADCVAL * Rser
+ * Rp = ------------------------
+ *         ADCBITS
+ *     2         * AMP - ADCVAL
+ *</pre>
+ *
+ * And after that NTC obvisiously is:
+ *<pre>
+ *        Rpar * Rp
+ * NTC = ----------
+ *        Rpar - Rp
+ *</pre>
+ *
+ *
+ * The function ntc_hw_read() compute the resistence using these formulas above.
+ */
+
+#ifndef HW_NTC_H
+#define HW_NTC_H
+
+#include "ntc_map.h"
+
+#include <cfg/debug.h>
+
+#include <drv/ntc.h>
+#include <drv/adc.h>
+
+#warning TODO:This is an example implementation, you must implement it!
+
+extern const res_t      NTC_RSER[NTC_CNT];
+extern const res_t      NTC_RPAR[NTC_CNT];
+extern const amp_t      NTC_AMP[NTC_CNT];
+extern const NtcHwInfo* NTC_INFO[NTC_CNT];
+
+
+/*!
+ * Read the resistence of ntc device \a dev.
+ * Return the result in res_t type.
+ */
+INLINE res_t ntc_hw_read(NtcDev dev)
+{
+       ASSERT(dev < NTC_CNT);
+       // See above for formula explanation.
+       adcread_t adcval = adc_read((uint16_t)dev);
+       float rp = (adcval * NTC_RSER[dev] ) / ((1 << adc_bits()) * NTC_AMP[dev] - adcval);
+
+       //kprintf("Rp[%f], Rntc[%f]\n", rp/100, ((NTC_RPAR[dev] * rp) / (NTC_RPAR[dev] - rp)) / 100.0);
+
+       return ( (NTC_RPAR[dev] * rp) / (NTC_RPAR[dev] - rp) );
+}
+
+
+/*!
+ * Return the info (aka the table) associated with ntc device \a dev.
+ */
+INLINE const NtcHwInfo* ntc_hw_getInfo(NtcDev dev)
+{
+       return NTC_INFO[dev];
+}
+
+#define NTC_HW_INIT    do  { /* Implement me! */ } while(0)
+
+#endif /* HW_NTC_H */