X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;ds=sidebyside;f=examples%2Fbenchmark%2Fkernel-core_avr%2Fhw%2Fhw_ntc.h;fp=examples%2Fbenchmark%2Fkernel-core_avr%2Fhw%2Fhw_ntc.h;h=49152a451cdb840fbe256f8fad06d3736c236805;hb=a86a8b231ae610974f053b1d2bd9172582f60a25;hp=0000000000000000000000000000000000000000;hpb=1d10dbcdf05ceaf77f1f6a394e6ee63050d6c89a;p=bertos.git diff --git a/examples/benchmark/kernel-core_avr/hw/hw_ntc.h b/examples/benchmark/kernel-core_avr/hw/hw_ntc.h new file mode 100644 index 00000000..49152a45 --- /dev/null +++ b/examples/benchmark/kernel-core_avr/hw/hw_ntc.h @@ -0,0 +1,136 @@ +/** + * \file + * + * + * \brief NTC hardware-specific definition + * + * \version $Id$ + * \author Francesco Sacchi + * + * 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: + * + *
+ *                 o Vref
+ *                 |
+ *                 |                               o Vref
+ *                 |                               |
+ *               -----                             |
+ *              |     |                        ---------
+ *              | Rser|                       |         |
+ *              |     |                       |         |
+ *               -----     -----              |   ADC   |
+ *                 | Vp   |     |             |         |
+ *      -----------|------| Amp |-------------|         |
+ *     |           |      |     |      Vadc   |         |
+ *   -----       -----     -----               ---------
+ *  |     |     |     |
+ *  | NTC |     | Rpar|
+ *  |     |     |     |
+ *   -----       -----
+ *     |           |
+ *     |           |
+ *   -----       -----
+ *    ---         ---
+ *
+ * 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: + * + *
+ *
+ *            ADCVAL * Rser
+ * Rp = ------------------------
+ *         ADCBITS
+ *	2         * AMP - ADCVAL
+ *
+ * + * And after that NTC obvisiously is: + *
+ *        Rpar * Rp
+ * NTC = ----------
+ *        Rpar - Rp
+ *
+ * + * + * 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 + +#include +#include + +#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 */