esp32: Add Sigma-Delta peripheral

docs/esp32/general.rst

@@ -53,6 +53,7 @@ For your convenience, some of technical specifications are provided below:
 * ADC: 12-bit SAR ADC up to 18 channels
 * DAC: 2 8-bit DACs
 * RMT: 8 channels allowing accurate pulse transmit/receive
+* SigmaDelta: 8 channels of hardware sigma-delta modulated output
 * Programming: using BootROM bootloader from UART - due to external FlashROM
   and always-available BootROM bootloader, the ESP32 is not brickable
 

docs/esp32/quickref.rst

@@ -655,6 +655,20 @@ The RMT is ESP32-specific and allows generation of accurate digital pulses with
     # The channel resolution is 100ns (1/(source_freq/clock_div)).
     r.write_pulses((1, 20, 2, 40), 0) # Send 0 for 100ns, 1 for 2000ns, 0 for 200ns, 1 for 4000ns
 
+Sigma-Delta
+-----------
+
+An ESP32-specific peripheral for generating hardware sigma-delta modulated output
+on any GPIO. See :ref:`esp32.SigmaDelta <esp32.SigmaDelta>` for details. Usage is::
+
+    import esp32
+    from machine import Pin
+
+    sd = esp32.SigmaDelta(0, pin=Pin(4), duty=0, prescale=80)
+    sd.duty(20)  # -128 to 127
+    sd.prescale(160)  # 0 to 255
+    sd.deinit()
+
 OneWire driver
 --------------
 

docs/library/esp32.rst

@@ -272,6 +272,46 @@ For more details see Espressif's `ESP-IDF RMT documentation.
     Passing in no argument will not change the channel.  This function returns
     the current channel number.
 
+.. _esp32.SigmaDelta:
+
+Sigma-Delta
+-----------
+
+ESP32 has a second-order sigma-delta modulation module. Each of the eight
+independent channels (0-7) are capable of outputting a binary hardware generated
+signal with the sigma-delta modulation::
+
+    import esp32
+    from machine import Pin
+
+    sd = esp32.SigmaDelta(3, pin=Pin(4), duty=0, prescale=80)
+    sd  # SigmaDelta(channel=3, pin=4, duty=0, prescale=80)
+    sd.duty(90)
+    sd.prescale(8)
+    sd.deinit()
+
+For more details see Espressif's `ESP-IDF Sigma-delta documentation.
+<https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/peripherals/sigmadelta.html>`_.
+
+.. class:: SigmaDelta(channel, \*, pin=None, duty=0, prescale=80)
+
+    This class provides access to the Sigma-Delta hardware signal generator.
+
+.. method:: SigmaDelta.duty(duty)
+
+    Set the duty of the output signal in the range -128 to 127. A zero value will
+    result in the output signal's duty of around 50%. Recommended range is -90 to 90.
+
+.. method:: SigmaDelta.prescale(prescale)
+
+    Set the sigma-delta channel's clock pre-scale value. The source clock is
+    APP_CLK, 80MHz. The clock frequency of the sigma-delta channel is
+    ``APP_CLK / pre_scale``.
+
+.. method:: SigmaDelta.deinit()
+
+    Disconnect the signal generator from the pin.
+
 Ultra-Low-Power co-processor
 ----------------------------
 

ports/esp32/esp32_common.cmake

@@ -80,6 +80,7 @@ list(APPEND MICROPY_SOURCE_PORT
     esp32_nvs.c
     esp32_partition.c
     esp32_rmt.c
+    esp32_sigmadelta.c
     esp32_ulp.c
     modesp32.c
     machine_hw_spi.c

ports/esp32/esp32_sigmadelta.c

@@ -0,0 +1,156 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Mike Causer <mcauser@gmail.com>
+ *
+ * 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 "py/runtime.h"
+#include "modmachine.h"
+#include "mphalport.h"
+#include "driver/sigmadelta.h"
+
+// Forward declaration
+extern const mp_obj_type_t esp32_sigmadelta_type;
+
+typedef struct _esp32_sigmadelta_obj_t {
+    mp_obj_base_t base;
+    uint8_t channel_id;
+    gpio_num_t pin;
+    int8_t duty;
+    uint8_t prescale;
+} esp32_sigmadelta_obj_t;
+
+STATIC mp_obj_t esp32_sigmadelta_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_channel,   MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = -1} },
+        { MP_QSTR_pin,       MP_ARG_REQUIRED | MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none} },
+        { MP_QSTR_duty,                        MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
+        { MP_QSTR_prescale,                    MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 80} },
+    };
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+    mp_uint_t channel_id = args[0].u_int;
+    gpio_num_t pin_id = machine_pin_get_id(args[1].u_obj);
+    mp_int_t duty = args[2].u_int;
+    mp_uint_t prescale = args[3].u_int;
+
+    if (duty < -128 || duty > 127) {
+        mp_raise_ValueError(MP_ERROR_TEXT("duty must be between -128 and 127"));
+    }
+
+    if (prescale > 255) {
+        mp_raise_ValueError(MP_ERROR_TEXT("prescale must be between 0 and 255"));
+    }
+
+    esp32_sigmadelta_obj_t *self = m_new_obj_with_finaliser(esp32_sigmadelta_obj_t);
+    self->base.type = &esp32_sigmadelta_type;
+    self->channel_id = channel_id;
+    self->pin = pin_id;
+    self->duty = duty;
+    self->prescale = prescale;
+
+    sigmadelta_config_t config;
+    config.channel = (sigmadelta_channel_t)self->channel_id;
+    config.sigmadelta_gpio = self->pin;
+    config.sigmadelta_duty = self->duty;
+    config.sigmadelta_prescale = self->prescale;
+
+    check_esp_err(sigmadelta_config(&config));
+
+    return MP_OBJ_FROM_PTR(self);
+}
+
+STATIC void esp32_sigmadelta_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
+    esp32_sigmadelta_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    if (self->pin != -1) {
+        mp_printf(print, "SigmaDelta(channel=%u, pin=%u, duty=%d, prescale=%u)",
+            self->channel_id, self->pin, self->duty, self->prescale);
+    } else {
+        mp_printf(print, "SigmaDelta()");
+    }
+}
+
+STATIC mp_obj_t esp32_sigmadelta_deinit(mp_obj_t self_in) {
+    esp32_sigmadelta_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    if (self->pin != -1) { // Check if channel has already been deinitialised.
+        gpio_matrix_out(self->pin, SIG_GPIO_OUT_IDX, 0, 0);
+        self->pin = -1; // -1 to indicate SigmaDelta is unused
+    }
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(esp32_sigmadelta_deinit_obj, esp32_sigmadelta_deinit);
+
+STATIC mp_obj_t esp32_sigmadelta_duty(size_t n_args, const mp_obj_t *args) {
+    esp32_sigmadelta_obj_t *self = MP_OBJ_TO_PTR(args[0]);
+    mp_int_t duty;
+    if (n_args == 1) {
+        // get
+        return mp_obj_new_int(self->duty);
+    }
+
+    // set
+    duty = mp_obj_get_int(args[1]);
+    if (duty < -128 || duty > 127) {
+        mp_raise_ValueError(MP_ERROR_TEXT("duty must be between -128 and 127"));
+    }
+    check_esp_err(sigmadelta_set_duty(self->channel_id, duty));
+    self->duty = duty;
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(esp32_sigmadelta_duty_obj, 1, 2, esp32_sigmadelta_duty);
+
+STATIC mp_obj_t esp32_sigmadelta_prescale(size_t n_args, const mp_obj_t *args) {
+    esp32_sigmadelta_obj_t *self = MP_OBJ_TO_PTR(args[0]);
+    mp_uint_t prescale;
+    if (n_args == 1) {
+        // get
+        return mp_obj_new_int(self->prescale);
+    }
+
+    // set
+    prescale = mp_obj_get_int(args[1]);
+    if (prescale > 255) {
+        mp_raise_ValueError(MP_ERROR_TEXT("prescale must be between 0 and 255"));
+    }
+    check_esp_err(sigmadelta_set_prescale(self->channel_id, prescale));
+    self->prescale = prescale;
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(esp32_sigmadelta_prescale_obj, 1, 2, esp32_sigmadelta_prescale);
+
+STATIC const mp_rom_map_elem_t esp32_sigmadelta_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR___del__), MP_ROM_PTR(&esp32_sigmadelta_deinit_obj) },
+    { MP_ROM_QSTR(MP_QSTR_deinit), MP_ROM_PTR(&esp32_sigmadelta_deinit_obj) },
+    { MP_ROM_QSTR(MP_QSTR_duty), MP_ROM_PTR(&esp32_sigmadelta_duty_obj) },
+    { MP_ROM_QSTR(MP_QSTR_prescale), MP_ROM_PTR(&esp32_sigmadelta_prescale_obj) },
+};
+STATIC MP_DEFINE_CONST_DICT(esp32_sigmadelta_locals_dict, esp32_sigmadelta_locals_dict_table);
+
+MP_DEFINE_CONST_OBJ_TYPE(
+    esp32_sigmadelta_type,
+    MP_QSTR_SIGMADELTA,
+    MP_TYPE_FLAG_NONE
+    make_new, esp32_sigmadelta_make_new,
+    print, esp32_sigmadelta_print,
+    locals_dict, &esp32_sigmadelta_locals_dict
+    );

ports/esp32/modesp32.c

@@ -208,6 +208,7 @@ STATIC const mp_rom_map_elem_t esp32_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_NVS), MP_ROM_PTR(&esp32_nvs_type) },
     { MP_ROM_QSTR(MP_QSTR_Partition), MP_ROM_PTR(&esp32_partition_type) },
     { MP_ROM_QSTR(MP_QSTR_RMT), MP_ROM_PTR(&esp32_rmt_type) },
+    { MP_ROM_QSTR(MP_QSTR_SigmaDelta), MP_ROM_PTR(&esp32_sigmadelta_type) },
     #if CONFIG_IDF_TARGET_ESP32 || CONFIG_IDF_TARGET_ESP32S2 || CONFIG_IDF_TARGET_ESP32S3
     { MP_ROM_QSTR(MP_QSTR_ULP), MP_ROM_PTR(&esp32_ulp_type) },
     #endif

ports/esp32/modesp32.h

@@ -64,6 +64,7 @@ extern int8_t esp32_rmt_bitstream_channel_id;
 extern const mp_obj_type_t esp32_nvs_type;
 extern const mp_obj_type_t esp32_partition_type;
 extern const mp_obj_type_t esp32_rmt_type;
+extern const mp_obj_type_t esp32_sigmadelta_type;
 extern const mp_obj_type_t esp32_ulp_type;
 
 esp_err_t rmt_driver_install_core1(uint8_t channel_id);