Add SCD41 MicroPython bindings

pull/174/head
Phil Howard 2021-07-23 16:37:21 +01:00
rodzic 0eeada72d7
commit 6d6803612a
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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)

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# 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.

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#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);
////////////////////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////////

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#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);
}
}

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// 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);

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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"
)

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@ -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)