Add SCD41 MicroPython bindings

micropython/examples/breakout_scd41/scd41_demo.py

@@ -0,0 +1,15 @@
+import time
+
+import pimoroni_i2c
+import breakout_scd41
+
+i2c = pimoroni_i2c.PimoroniI2C(4, 5)
+
+breakout_scd41.init(i2c)
+breakout_scd41.start()
+
+while True:
+    if breakout_scd41.ready():
+        co2, temperature, humidity = breakout_scd41.measure()
+        print(co2, temperature, humidity)
+        time.sleep(1.0)

micropython/modules/breakout_scd41/README.md

@@ -0,0 +1,39 @@
+# SCD41 CO2 Sensor Driver <!-- omit in toc -->
+
+## Getting Started
+
+Construct a new PimoroniI2C instance for your specific board. Breakout Garden uses pins 4 & 5 and Pico Explorer uses pins 20 & 21.
+
+Since SCD41 has a fixed I2C address and the Sensirion SCD4x library is used under the hood, it's wrapped up as a module for Python.
+
+Import the `breakout_scd41` and call `init` to set up I2C:
+
+```python
+import time
+
+import pimoroni_i2c
+import breakout_scd41
+
+i2c = pimoroni_i2c.PimoroniI2C(4, 5)
+
+breakout_scd41.init(i2c)
+```
+
+## Taking Measurements
+
+Before taking a measurement you must start periodic measurement by calling `start()`.
+
+Poll on `ready()` and use `measure()` to read the result when it's `True`:
+
+```python
+breakout_scd41.start()
+
+while True:
+    if breakout_scd41.ready():
+        co2, temperature, humidity = breakout_scd41.measure()
+        print(co2, temperature, humidity)
+        time.sleep(1.0)
+```
+
+The `measure()` method will return a Tuple containing the CO2 reading, temperature in degrees C and humidity.
+

micropython/modules/breakout_scd41/breakout_scd41.c

@@ -0,0 +1,54 @@
+#include "breakout_scd41.h"
+
+/***** Constants *****/
+
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// SCD41 Module
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+/***** Module Functions *****/
+// Init, optionally (though you really should supply it) accepts a PimoroniI2C instance
+STATIC MP_DEFINE_CONST_FUN_OBJ_KW(scd41_init_obj, 0, scd41_init);
+
+// Start/Stop measurement, no args (module-level, so no "self")
+STATIC MP_DEFINE_CONST_FUN_OBJ_0(scd41_start_periodic_measurement_obj, scd41_start_periodic_measurement);
+STATIC MP_DEFINE_CONST_FUN_OBJ_0(scd41_stop_periodic_measurement_obj, scd41_stop_periodic_measurement);
+STATIC MP_DEFINE_CONST_FUN_OBJ_0(scd41_get_data_ready_obj, scd41_get_data_ready);
+
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(scd41_set_temperature_offset_obj, scd41_set_temperature_offset);
+STATIC MP_DEFINE_CONST_FUN_OBJ_0(scd41_get_temperature_offset_obj, scd41_get_temperature_offset);
+
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(scd41_set_sensor_altitude_obj, scd41_set_sensor_altitude);
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(scd41_set_ambient_pressure_obj, scd41_set_ambient_pressure);
+
+// No args here, either, we're home free!
+STATIC MP_DEFINE_CONST_FUN_OBJ_0(scd41_read_measurement_obj, scd41_read_measurement);
+
+/***** Globals Table *****/
+STATIC const mp_map_elem_t scd41_globals_table[] = {
+    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_breakout_scd41) },
+    { MP_ROM_QSTR(MP_QSTR_init), MP_ROM_PTR(&scd41_init_obj) },
+    { MP_ROM_QSTR(MP_QSTR_start), MP_ROM_PTR(&scd41_start_periodic_measurement_obj) },
+    { MP_ROM_QSTR(MP_QSTR_stop), MP_ROM_PTR(&scd41_stop_periodic_measurement_obj) },
+    { MP_ROM_QSTR(MP_QSTR_measure), MP_ROM_PTR(&scd41_read_measurement_obj) },
+    { MP_ROM_QSTR(MP_QSTR_ready), MP_ROM_PTR(&scd41_get_data_ready_obj) },
+
+    { MP_ROM_QSTR(MP_QSTR_set_temperature_offset), MP_ROM_PTR(&scd41_set_temperature_offset_obj) },
+    { MP_ROM_QSTR(MP_QSTR_get_temperature_offset), MP_ROM_PTR(&scd41_get_temperature_offset_obj) },
+
+    { MP_ROM_QSTR(MP_QSTR_set_sensor_altitude), MP_ROM_PTR(&scd41_set_sensor_altitude_obj) },
+    { MP_ROM_QSTR(MP_QSTR_set_ambient_pressure), MP_ROM_PTR(&scd41_set_ambient_pressure_obj) },
+};
+STATIC MP_DEFINE_CONST_DICT(mp_module_scd41_globals, scd41_globals_table);
+
+/***** Module Definition *****/
+const mp_obj_module_t scd41_user_cmodule = {
+    .base = { &mp_type_module },
+    .globals = (mp_obj_dict_t*)&mp_module_scd41_globals,
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+MP_REGISTER_MODULE(MP_QSTR_breakout_scd41, scd41_user_cmodule, MODULE_BREAKOUT_SCD41_ENABLED);
+////////////////////////////////////////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////////////////////////////////////////

micropython/modules/breakout_scd41/breakout_scd41.cpp

@@ -0,0 +1,177 @@
+#include "hardware/spi.h"
+#include "hardware/sync.h"
+#include "pico/binary_info.h"
+
+#include "scd4x_i2c.h"
+#include "sensirion_common.h"
+#include "sensirion_i2c_hal.h"
+#include "common/pimoroni_i2c.hpp"
+
+using namespace pimoroni;
+
+bool scd41_initialised = false;
+
+
+extern "C" {
+#include "breakout_scd41.h"
+#include "pimoroni_i2c.h"
+
+/***** I2C Struct *****/
+typedef struct _PimoroniI2C_obj_t {
+    mp_obj_base_t base;
+    I2C *i2c;
+} _PimoroniI2C_obj_t;
+
+#define NOT_INITIALISED_MSG     "SCD41: Not initialised. Call scd41.init(<i2c instance>) first."
+#define READ_FAIL_MSG           "SCD41: Reading failed."
+#define FAIL_MSG                "SCD41: Error."
+#define SAMPLE_FAIL_MSG         "SCD41: Read invalid sample."
+
+mp_obj_t scd41_init(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+
+    enum { ARG_i2c };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_i2c, MP_ARG_OBJ, {.u_obj = nullptr} }
+    };
+
+    // Parse args.
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    // Perform the I2C type checking incantations
+    if(!MP_OBJ_IS_TYPE(args[ARG_i2c].u_obj, &PimoroniI2C_type)) {
+        mp_raise_ValueError(MP_ERROR_TEXT("SCD41: Bad i2C object"));
+        return mp_const_none;
+    }
+
+    _PimoroniI2C_obj_t *i2c = (_PimoroniI2C_obj_t *)MP_OBJ_TO_PTR(args[ARG_i2c].u_obj);
+
+    sensirion_i2c_hal_init(i2c->i2c);
+    scd41_initialised = true;
+
+    return mp_const_none;
+}
+
+mp_obj_t scd41_stop_periodic_measurement() {
+    if(!scd41_initialised) {
+        mp_raise_msg(&mp_type_RuntimeError, NOT_INITIALISED_MSG);
+        return mp_const_none;
+    }
+    scd4x_stop_periodic_measurement();
+    return mp_const_none;
+}
+
+mp_obj_t scd41_start_periodic_measurement() {
+    if(!scd41_initialised) {
+        mp_raise_msg(&mp_type_RuntimeError, NOT_INITIALISED_MSG);
+        return mp_const_none;
+    }
+    int error = scd4x_start_periodic_measurement();
+    if(error) {
+        mp_raise_msg(&mp_type_RuntimeError, FAIL_MSG);
+    }
+
+    return mp_const_none;
+}
+
+mp_obj_t scd41_get_data_ready() {
+    if(!scd41_initialised) {
+        mp_raise_msg(&mp_type_RuntimeError, NOT_INITIALISED_MSG);
+        return mp_const_none;
+    }
+    uint16_t data_ready = 0;
+    int error = scd4x_get_data_ready_status(&data_ready);
+    if(error) {
+        mp_raise_msg(&mp_type_RuntimeError, READ_FAIL_MSG);
+        return mp_const_none;
+    }
+    // The datasheet doesn't really say *which* bit might be 1 if data is ready...
+    // so check if the least significant eleven bits are != 0
+    return (data_ready & 0x7ff) ? mp_const_true : mp_const_false;
+}
+
+mp_obj_t scd41_set_temperature_offset(mp_obj_t offset) {
+    if(!scd41_initialised) {
+        mp_raise_msg(&mp_type_RuntimeError, NOT_INITIALISED_MSG);
+        return mp_const_none;
+    }
+    float o = mp_obj_get_float(offset);
+    int error = scd4x_set_temperature_offset(o);
+    if(error) {
+        mp_raise_msg(&mp_type_RuntimeError, FAIL_MSG);
+    }
+
+    return mp_const_none;
+}
+
+mp_obj_t scd41_get_temperature_offset() {
+    if(!scd41_initialised) {
+        mp_raise_msg(&mp_type_RuntimeError, NOT_INITIALISED_MSG);
+        return mp_const_none;
+    }
+
+    int32_t t_offset;
+    int error = scd4x_get_temperature_offset(&t_offset);
+    if(error) {
+        mp_raise_msg(&mp_type_RuntimeError, FAIL_MSG);
+        return mp_const_none;
+    }
+
+    return mp_obj_new_int(t_offset);
+}
+
+mp_obj_t scd41_set_sensor_altitude(mp_obj_t altitude) {
+    if(!scd41_initialised) {
+        mp_raise_msg(&mp_type_RuntimeError, NOT_INITIALISED_MSG);
+        return mp_const_none;
+    }
+    int a = mp_obj_get_int(altitude);
+    int error = scd4x_set_sensor_altitude(a);
+    if(error) {
+        mp_raise_msg(&mp_type_RuntimeError, FAIL_MSG);
+    }
+
+    return mp_const_none;
+}
+
+mp_obj_t scd41_set_ambient_pressure(mp_obj_t pressure) {
+    if(!scd41_initialised) {
+        mp_raise_msg(&mp_type_RuntimeError, NOT_INITIALISED_MSG);
+        return mp_const_none;
+    }
+    int p = mp_obj_get_int(pressure);
+    int error = scd4x_set_ambient_pressure(p);
+    if(error) {
+        mp_raise_msg(&mp_type_RuntimeError, FAIL_MSG);
+    }
+
+    return mp_const_none;
+}
+
+
+mp_obj_t scd41_read_measurement() {
+    uint16_t co2;
+    int32_t temperature;
+    int32_t humidity;
+    if(!scd41_initialised) {
+        mp_raise_msg(&mp_type_RuntimeError, NOT_INITIALISED_MSG);
+        return mp_const_none;
+    }
+    int  error = scd4x_read_measurement(&co2, &temperature, &humidity);
+    if(error) {
+        mp_raise_msg(&mp_type_RuntimeError, READ_FAIL_MSG);
+        return mp_const_none;
+    }
+
+    if(co2 == 0) {
+        mp_raise_msg(&mp_type_RuntimeError, SAMPLE_FAIL_MSG);
+        return mp_const_none;
+    }
+
+    mp_obj_t tuple[3];
+    tuple[0] = mp_obj_new_float(co2);
+    tuple[1] = mp_obj_new_float(temperature / 1000.0f);
+    tuple[2] = mp_obj_new_float(humidity / 1000.0f);
+    return mp_obj_new_tuple(3, tuple);
+}
+}

micropython/modules/breakout_scd41/breakout_scd41.h

@@ -0,0 +1,15 @@
+// Include MicroPython API.
+#include "py/runtime.h"
+#include "py/objstr.h"
+
+// Declare the functions we'll make available in Python
+extern mp_obj_t scd41_init(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args);
+extern mp_obj_t scd41_start_periodic_measurement();
+extern mp_obj_t scd41_stop_periodic_measurement();
+extern mp_obj_t scd41_read_measurement();
+extern mp_obj_t scd41_get_data_ready();
+
+extern mp_obj_t scd41_set_temperature_offset(mp_obj_t offset);
+extern mp_obj_t scd41_get_temperature_offset();
+extern mp_obj_t scd41_set_sensor_altitude(mp_obj_t altitude);
+extern mp_obj_t scd41_set_ambient_pressure(mp_obj_t pressure);

micropython/modules/breakout_scd41/micropython.cmake

@@ -0,0 +1,32 @@
+set(MOD_NAME breakout_scd41)
+set(DRIVER ${CMAKE_CURRENT_LIST_DIR}/../../../drivers/scd4x)
+string(TOUPPER ${MOD_NAME} MOD_NAME_UPPER)
+add_library(usermod_${MOD_NAME} INTERFACE)
+
+target_sources(usermod_${MOD_NAME} INTERFACE
+    ${CMAKE_CURRENT_LIST_DIR}/${MOD_NAME}.c
+    ${CMAKE_CURRENT_LIST_DIR}/${MOD_NAME}.cpp
+    ${DRIVER}/src/scd4x_i2c.c
+    ${DRIVER}/src/sensirion_common.c
+    ${DRIVER}/src/sensirion_i2c.c
+    ${DRIVER}/i2c_hal.cpp
+    ${DRIVER}/scd4x.cpp
+)
+
+target_include_directories(usermod_${MOD_NAME} INTERFACE
+    ${CMAKE_CURRENT_LIST_DIR}
+    ${DRIVER}
+    ${DRIVER}/src
+)
+
+target_compile_definitions(usermod_${MOD_NAME} INTERFACE
+    -DMODULE_${MOD_NAME_UPPER}_ENABLED=1
+)
+
+target_link_libraries(usermod INTERFACE usermod_${MOD_NAME})
+
+set_source_files_properties(
+    ${CMAKE_CURRENT_LIST_DIR}/breakout_scd41.c
+    PROPERTIES COMPILE_FLAGS
+    "-Wno-discarded-qualifiers -Wno-implicit-int"
+)

micropython/modules/micropython.cmake

@@ -28,6 +28,7 @@ include(breakout_bme68x/micropython)
 include(breakout_bme280/micropython)
 include(breakout_bmp280/micropython)
 include(breakout_icp10125/micropython)
+include(breakout_scd41/micropython)
 
 include(pico_scroll/micropython)
 include(pico_rgb_keypad/micropython)