samd/machine_dac: Add the machine.DAC class.

It suuports 1 channel @ 10 bit for SAMD21, 2 channels @ 12 bit for SAMD51.

Instantiation by:

    dac = machine.DAC(ch) # 0 or 1

Method write:

    dac.write(value)

The output voltage range is 0..Vdd.

ports/samd/Makefile

@@ -91,6 +91,7 @@ SRC_C = \
 	clock_config.c \
 	help.c \
 	machine_adc.c \
+	machine_dac.c \
 	machine_i2c.c \
 	machine_led.c \
 	machine_pin.c \
@@ -149,6 +150,7 @@ endif
 # List of sources for qstr extraction
 SRC_QSTR += \
 	machine_adc.c \
+	machine_dac.c \
 	machine_i2c.c \
 	machine_led.c \
 	machine_pin.c \

ports/samd/machine_dac.c

@@ -0,0 +1,162 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Nick Moore
+ * Copyright (c) 2022 Robert Hammelrath
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdint.h>
+#include "py/obj.h"
+#include "py/runtime.h"
+#include "py/mphal.h"
+
+#include "sam.h"
+#include "pin_af.h"
+#include "modmachine.h"
+
+typedef struct _dac_obj_t {
+    mp_obj_base_t base;
+    uint8_t id;
+    mp_hal_pin_obj_t gpio_id;
+} dac_obj_t;
+
+STATIC const dac_obj_t dac_obj[] = {
+    #if defined(MCU_SAMD21)
+    {{&machine_dac_type}, 0, PIN_PA02},
+    #elif defined(MCU_SAMD51)
+    {{&machine_dac_type}, 0, PIN_PA02},
+    {{&machine_dac_type}, 1, PIN_PA05},
+    #endif
+};
+Dac *const dac_bases[] = DAC_INSTS;
+
+#if defined(MCU_SAMD21)
+#define MAX_DAC_VALUE  (1023)
+#elif defined(MCU_SAMD51)
+#define MAX_DAC_VALUE  (4095)
+static bool dac_init = false;
+#endif
+
+
+STATIC mp_obj_t dac_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw,
+    const mp_obj_t *args) {
+
+    mp_arg_check_num(n_args, n_kw, 1, 1, true);
+    uint8_t id = mp_obj_get_int(args[0]);
+    const dac_obj_t *self = NULL;
+    if (0 <= id && id <= MP_ARRAY_SIZE(dac_obj)) {
+        self = &dac_obj[id];
+    } else {
+        mp_raise_ValueError(MP_ERROR_TEXT("invalid Pin for DAC"));
+    }
+
+    Dac *dac = dac_bases[0]; // Just one DAC
+
+    // Init DAC
+    #if defined(MCU_SAMD21)
+
+    // Configuration SAMD21
+    // Enable APBC clocks and PCHCTRL clocks; GCLK3 at 1 MHz
+    PM->APBCMASK.reg |= PM_APBCMASK_DAC;
+    GCLK->CLKCTRL.reg = GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN_GCLK3 | GCLK_CLKCTRL_ID_DAC;
+    while (GCLK->STATUS.bit.SYNCBUSY) {
+    }
+    // Reset DAC registers
+    dac->CTRLA.bit.SWRST = 1;
+    while (dac->CTRLA.bit.SWRST) {
+    }
+    dac->CTRLB.reg = DAC_CTRLB_EOEN | DAC_CTRLB_REFSEL(DAC_CTRLB_REFSEL_AVCC_Val);
+    // Enable DAC and wait to be ready
+    dac->CTRLA.bit.ENABLE = 1;
+    while (dac->STATUS.bit.SYNCBUSY) {
+    }
+
+    #elif defined(MCU_SAMD51)
+
+    // Configuration SAMD51
+    // Enable APBD clocks and PCHCTRL clocks; GCLK3 at 8 MHz
+    if (!dac_init) {
+        dac_init = true;
+        MCLK->APBDMASK.reg |= MCLK_APBDMASK_DAC;
+        GCLK->PCHCTRL[DAC_GCLK_ID].reg = GCLK_PCHCTRL_GEN_GCLK3 | GCLK_PCHCTRL_CHEN;
+
+        // Reset DAC registers
+        dac->CTRLA.bit.SWRST = 1;
+        while (dac->CTRLA.bit.SWRST) {
+        }
+        dac->CTRLB.reg = DAC_CTRLB_REFSEL(DAC_CTRLB_REFSEL_VDDANA_Val);
+    } else {
+        dac->CTRLA.bit.ENABLE = 0;
+        while (dac->SYNCBUSY.bit.ENABLE) {
+        }
+    }
+    dac->DACCTRL[self->id].reg = DAC_DACCTRL_ENABLE | DAC_DACCTRL_REFRESH(2) | DAC_DACCTRL_CCTRL_CC12M;
+
+    // Enable DAC and wait to be ready
+    dac->CTRLA.bit.ENABLE = 1;
+    while (dac->SYNCBUSY.bit.ENABLE) {
+    }
+    #endif
+
+    // Set the port as given in self->gpio_id as DAC
+    mp_hal_set_pin_mux(self->gpio_id, ALT_FCT_DAC);
+
+    return MP_OBJ_FROM_PTR(self);
+}
+
+STATIC void dac_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    dac_obj_t *self = self_in;
+    mp_printf(print, "DAC(%u) PIN_PA%02u", self->id, self->gpio_id);
+}
+
+STATIC mp_obj_t dac_write(mp_obj_t self_in, mp_obj_t value_in) {
+    Dac *dac = dac_bases[0]; // Just one DAC
+    int value = mp_obj_get_int(value_in);
+    if (value < 0 || value > MAX_DAC_VALUE) {
+        mp_raise_ValueError(MP_ERROR_TEXT("value out of range"));
+    }
+    #if defined(MCU_SAMD21)
+    dac->DATA.reg = value;
+    #elif defined(MCU_SAMD51)
+    dac_obj_t *self = self_in;
+    dac->DATA[self->id].reg = value;
+    #endif
+
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_2(dac_write_obj, dac_write);
+
+STATIC const mp_rom_map_elem_t dac_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&dac_write_obj) },
+};
+
+STATIC MP_DEFINE_CONST_DICT(dac_locals_dict, dac_locals_dict_table);
+
+MP_DEFINE_CONST_OBJ_TYPE(
+    machine_dac_type,
+    MP_QSTR_DAC,
+    MP_TYPE_FLAG_NONE,
+    make_new, dac_make_new,
+    print, dac_print,
+    locals_dict, &dac_locals_dict
+    );

ports/samd/modmachine.c

@@ -150,6 +150,7 @@ STATIC const mp_rom_map_elem_t machine_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_unique_id),           MP_ROM_PTR(&machine_unique_id_obj) },
 
     { MP_ROM_QSTR(MP_QSTR_ADC),                 MP_ROM_PTR(&machine_adc_type) },
+    { MP_ROM_QSTR(MP_QSTR_DAC),                 MP_ROM_PTR(&machine_dac_type) },
     { MP_ROM_QSTR(MP_QSTR_LED),                 MP_ROM_PTR(&machine_led_type) },
     { MP_ROM_QSTR(MP_QSTR_Pin),                 MP_ROM_PTR(&machine_pin_type) },
     { MP_ROM_QSTR(MP_QSTR_PWM),                 MP_ROM_PTR(&machine_pwm_type) },

ports/samd/modmachine.h

@@ -29,6 +29,7 @@
 #include "py/obj.h"
 
 extern const mp_obj_type_t machine_adc_type;
+extern const mp_obj_type_t machine_dac_type;
 extern const mp_obj_type_t machine_hw_i2c_type;
 extern const mp_obj_type_t machine_led_type;
 extern const mp_obj_type_t machine_pin_type;

ports/samd/pin_af.h

@@ -81,6 +81,7 @@ typedef struct _pwm_config_t {
 
 #define ALT_FCT_EIC       0
 #define ALT_FCT_ADC       1
+#define ALT_FCT_DAC       1
 #define ALT_FCT_SERCOM1   2
 #define ALT_FCT_SERCOM2   3