import adc driver and test for moisture sensor

boards/samr21-xpro/Makefile.features

@@ -8,6 +8,7 @@ FEATURES_PROVIDED += periph_rtt
 FEATURES_PROVIDED += periph_spi
 FEATURES_PROVIDED += periph_timer
 FEATURES_PROVIDED += periph_uart
+FEATURES_PROVIDED += periph_adc
 
 # Various other features (if any)
 FEATURES_PROVIDED += cpp

boards/samr21-xpro/include/board.h

@@ -70,7 +70,7 @@ extern "C" {
  * @name Define UART device and baudrate for stdio
  * @{
  */
-#define STDIO               UART_0
+#define STDIO               UART_1
 #define STDIO_BAUDRATE      (115200U)
 #define STDIO_RX_BUFSIZE    (64U)
 /** @} */

boards/samr21-xpro/include/periph_conf.h

@@ -263,6 +263,129 @@ static const pwm_conf_t pwm_config[] = {
 #define RTT_RUNSTDBY        (1)         /* Keep RTT running in sleep states */
 /** @} */
 
+/** @} */
+
+/**
+ * @ ADC Configuration
+ * @{
+ */
+typedef struct {
+    PortGroup *port;
+    uint8_t pin;
+    uint8_t muxpos;                 /* see datasheet sec 30.8.8 */
+} adc_conf_t;
+
+#define ADC_NUMOF                          (1U)
+#define ADC_0_EN                           1
+#define ADC_MAX_CHANNELS                   8
+
+/* ADC 0 device configuration */
+#define ADC_0_DEV                          ADC
+#define ADC_0_PORT                         (PORT->Group[0])
+#define ADC_0_IRQ                          ADC_IRQn
+#define ADC_0_CHANNELS                     6 // ignore PA04 & PA05 due to EDBG UART conflict
+
+/* ADC 0 Default values */
+#define ADC_0_CLK_SOURCE                   0 /* GCLK_GENERATOR_0 */
+#define ADC_0_PRESCALER                    ADC_CTRLB_PRESCALER_DIV512
+#define ADC_0_WINDOW_MODE                  ADC_WINCTRL_WINMODE_DISABLE
+#define ADC_0_WINDOW_LOWER                 0
+#define ADC_0_WINDOW_HIGHER                0
+
+#define ADC_0_CORRECTION_EN                0 /* disabled */
+#define ADC_0_GAIN_CORRECTION              ADC_GAINCORR_RESETVALUE
+#define ADC_0_OFFSET_CORRECTION            ADC_OFFSETCORR_RESETVALUE
+#define ADC_0_SAMPLE_LENGTH                0
+#define ADC_0_PIN_SCAN_OFFSET_START        0 /* disabled */
+#define ADC_0_PIN_SCAN_INPUT_TO_SCAN       0 /* disabled */
+#define ADC_0_LEFT_ADJUST                  0 /* disabled */
+#define ADC_0_DIFFERENTIAL_MODE            0 /* disabled */
+#define ADC_0_FREE_RUNNING                 0 /* disabled */
+#define ADC_0_EVENT_ACTION                 0 /* disabled */
+#define ADC_0_RUN_IN_STANDBY               0 /* disabled */
+
+/* ADC 0 Module Status flags */
+#define ADC_0_STATUS_RESULT_READY          (1UL << 0)
+#define ADC_0_STATUS_WINDOW                (1UL << 1)
+#define ADC_0_STATUS_OVERRUN               (1UL << 2)
+
+#if ADC_0_CHANNELS
+#if ADC_0_DIFFERENTIAL_MODE
+/*  In differential mode, we can only pick one positive
+ *  and one negative input.
+ */
+#define ADC_0_POS_INPUT                    ADC_INPUTCTRL_MUXPOS_PIN6
+#define ADC_0_NEG_INPUT                    ADC_INPUTCTRL_MUXNEG_PIN7
+#else
+/*  If we're not in differential mode, we can use any of
+ *  ADC positive input pins the SAMR21-XPRO provides.  Each pin is
+ *  a separate ADC "channel".
+ */
+static const adc_conf_t adc_config[] = {
+    /* port, pin, muxpos */
+    //{&PORT->Group[0], 4, 0x4}, // we cannot use these as well as use EDBG serial TX/RX
+    //{&PORT->Group[0], 5, 0x5}, // because PA04 & PA05 read/write directly to EDBG serial port.
+    {&PORT->Group[0], ADC_INPUTCTRL_MUXPOS_PIN6, 0x6},    // PA06
+    {&PORT->Group[0], ADC_INPUTCTRL_MUXPOS_PIN7, 0x7},    // PA07
+    {&PORT->Group[0], ADC_INPUTCTRL_MUXPOS_PIN16, 0x10},   // PA08
+    {&PORT->Group[0], ADC_INPUTCTRL_MUXPOS_PIN17, 0x11},   // PA09
+    {&PORT->Group[0], ADC_INPUTCTRL_MUXPOS_PIN10, 0xA},    // PB02
+    {&PORT->Group[0], ADC_INPUTCTRL_MUXPOS_PIN11, 0xB},    // PB03
+};
+#endif
+#endif
+
+
+/* ADC 0 Gain Factor */
+#define ADC_0_GAIN_FACTOR_1X               ADC_INPUTCTRL_GAIN_1X
+#define ADC_0_GAIN_FACTOR_2X               ADC_INPUTCTRL_GAIN_2X
+#define ADC_0_GAIN_FACTOR_4X               ADC_INPUTCTRL_GAIN_4X
+#define ADC_0_GAIN_FACTOR_8X               ADC_INPUTCTRL_GAIN_8X
+#define ADC_0_GAIN_FACTOR_16X              ADC_INPUTCTRL_GAIN_16X
+/* Use this to define the value used */
+#define ADC_0_GAIN_FACTOR_DEFAULT          ADC_0_GAIN_FACTOR_1X
+
+/* ADC 0 Resolutions */
+#define ADC_0_RES_8BIT                     ADC_CTRLB_RESSEL_8BIT
+#define ADC_0_RES_10BIT                    ADC_CTRLB_RESSEL_10BIT
+#define ADC_0_RES_12BIT                    ADC_CTRLB_RESSEL_12BIT
+#define ADC_0_RES_16BIT                    ADC_CTRLB_RESSEL_16BIT
+
+/* ADC 0 Voltage reference */
+#define ADC_0_REF_INT_1V                   ADC_REFCTRL_REFSEL_INT1V
+#define ADC_0_REF_EXT_B                    ADC_REFCTRL_REFSEL_AREFB
+#define ADC_0_REF_COM_EN                   1
+/* Use this to define the value used */
+#define ADC_0_REF_DEFAULT                  ADC_REFCTRL_REFSEL_AREFB//ADC_0_REF_INT_1V
+
+/* ADC 0 ACCUMULATE */
+#define ADC_0_ACCUM_DISABLE                ADC_AVGCTRL_SAMPLENUM_1
+#define ADC_0_ACCUM_2                      ADC_AVGCTRL_SAMPLENUM_2
+#define ADC_0_ACCUM_4                      ADC_AVGCTRL_SAMPLENUM_4
+#define ADC_0_ACCUM_8                      ADC_AVGCTRL_SAMPLENUM_8
+#define ADC_0_ACCUM_16                     ADC_AVGCTRL_SAMPLENUM_16
+#define ADC_0_ACCUM_32                     ADC_AVGCTRL_SAMPLENUM_32
+#define ADC_0_ACCUM_64                     ADC_AVGCTRL_SAMPLENUM_64
+#define ADC_0_ACCUM_128                    ADC_AVGCTRL_SAMPLENUM_128
+#define ADC_0_ACCUM_256                    ADC_AVGCTRL_SAMPLENUM_256
+#define ADC_0_ACCUM_512                    ADC_AVGCTRL_SAMPLENUM_512
+#define ADC_0_ACCUM_1024                   ADC_AVGCTRL_SAMPLENUM_1024
+/* Use this to define the value used */
+#define ADC_0_ACCUM_DEFAULT                ADC_0_ACCUM_DISABLE
+
+/* ADC 0 DIVIDE RESULT */
+#define ADC_0_DIV_RES_DISABLE              0
+#define ADC_0_DIV_RES_2                    1
+#define ADC_0_DIV_RES_4                    2
+#define ADC_0_DIV_RES_8                    3
+#define ADC_0_DIV_RES_16                   4
+#define ADC_0_DIV_RES_32                   5
+#define ADC_0_DIV_RES_64                   6
+#define ADC_0_DIV_RES_128                  7
+/* Use this to define the value used */
+#define ADC_0_DIV_RES_DEFAULT             ADC_0_DIV_RES_DISABLE
+/** @} */
+
 #ifdef __cplusplus
 }
 #endif