bme280 telemetry output to uart

.gitignore

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+.pio

include/README

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+
+This directory is intended for project header files.
+
+A header file is a file containing C declarations and macro definitions
+to be shared between several project source files. You request the use of a
+header file in your project source file (C, C++, etc) located in `src` folder
+by including it, with the C preprocessing directive `#include'.
+
+```src/main.c
+
+#include "header.h"
+
+int main (void)
+{
+ ...
+}
+```
+
+Including a header file produces the same results as copying the header file
+into each source file that needs it. Such copying would be time-consuming
+and error-prone. With a header file, the related declarations appear
+in only one place. If they need to be changed, they can be changed in one
+place, and programs that include the header file will automatically use the
+new version when next recompiled. The header file eliminates the labor of
+finding and changing all the copies as well as the risk that a failure to
+find one copy will result in inconsistencies within a program.
+
+In C, the convention is to give header files names that end with `.h'.
+
+Read more about using header files in official GCC documentation:
+
+* Include Syntax
+* Include Operation
+* Once-Only Headers
+* Computed Includes
+
+https://gcc.gnu.org/onlinedocs/cpp/Header-Files.html

lib/README

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+
+This directory is intended for project specific (private) libraries.
+PlatformIO will compile them to static libraries and link into the executable file.
+
+The source code of each library should be placed in a separate directory
+("lib/your_library_name/[Code]").
+
+For example, see the structure of the following example libraries `Foo` and `Bar`:
+
+|--lib
+|  |
+|  |--Bar
+|  |  |--docs
+|  |  |--examples
+|  |  |--src
+|  |     |- Bar.c
+|  |     |- Bar.h
+|  |  |- library.json (optional. for custom build options, etc) https://docs.platformio.org/page/librarymanager/config.html
+|  |
+|  |--Foo
+|  |  |- Foo.c
+|  |  |- Foo.h
+|  |
+|  |- README --> THIS FILE
+|
+|- platformio.ini
+|--src
+   |- main.c
+
+Example contents of `src/main.c` using Foo and Bar:
+```
+#include <Foo.h>
+#include <Bar.h>
+
+int main (void)
+{
+  ...
+}
+
+```
+
+The PlatformIO Library Dependency Finder will find automatically dependent
+libraries by scanning project source files.
+
+More information about PlatformIO Library Dependency Finder
+- https://docs.platformio.org/page/librarymanager/ldf.html

platformio.ini

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+; PlatformIO Project Configuration File
+;
+;   Build options: build flags, source filter
+;   Upload options: custom upload port, speed and extra flags
+;   Library options: dependencies, extra library storages
+;   Advanced options: extra scripting
+;
+; Please visit documentation for the other options and examples
+; https://docs.platformio.org/page/projectconf.html
+
+[env:pro16MHzatmega328]
+platform = atmelavr
+board = pro16MHzatmega328
+monitor_speed = 9600
+lib_deps =
+    https://github.com/Sylaina/bme280.git
+

src/main.c

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+/**
+ * Copyright (C) PlatformIO <contact@platformio.org>
+ * See LICENSE for details.
+ */
+
+#define BAUD 9600
+
+#include <avr/io.h>
+#include <util/delay.h>
+#include <util/setbaud.h>
+
+#include "sensor_bme280.h"
+#include "bme280.h"
+#include "i2c.h"
+#include <stdio.h>
+
+
+void uart_init(void) {
+    // Set baud rate
+    UBRR0H = UBRRH_VALUE;
+    UBRR0L = UBRRL_VALUE;
+
+    // Don't use double rate
+    UCSR0A &= ~(1 << U2X0);
+
+    // Enable rx and tx
+    UCSR0B = (1 << TXEN0) | (1 << RXEN0);
+
+    // Set frame format: 8-N-1
+    UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);
+}
+
+void uart_putchar(char c) {
+    while(!(UCSR0A & (1 << UDRE0)));
+
+    UDR0 = c;
+}
+
+void uart_putstr(const char *str) {
+    while(*str) {
+        uart_putchar(*str++);
+    }
+}
+
+char * format_temperature(float temp) {
+    uint8_t min_width = 3;
+
+    char * out[min_width];
+    dtostrf(temp, min_width, 1, out);
+
+    return out;
+}
+
+char * format_humidity(float humidity) {
+    uint8_t min_width = 5;
+
+    char out[min_width];
+    dtostrf(humidity, min_width, 2, out);
+
+    return out;
+}
+
+char * format_pressure(float pressure) {
+    uint8_t min_width = 3;
+
+    char out[min_width];
+    dtostrf(pressure, min_width, 1, out);
+
+    return out;
+}
+
+
+
+int main(void)
+{
+    uart_init();
+
+    // make the LED pin an output for PORTB5
+    DDRB = 1 << 5;
+
+    float temp = 0.0;
+    float pressure = 0.0;
+    float humidity = 0.0;
+
+    i2c_init();
+    _delay_ms(500);
+
+    uint8_t ret = bme280_init(1);
+    if(ret == 0x00) {
+        uart_putstr("\nbme280 detected by library.\r\n");
+    } else if(ret == 0x01) {
+        uart_putstr("\nbmp280 detected by library.\r\n");
+    } else if(ret == 0xFF) {
+        uart_putstr("\nno sensor detected.\r\n");
+    } else {
+        uart_putstr("\nunknown error.\r\n");
+    }
+
+    // Turn the green led on
+    PORTB |= 1 << 5;
+
+    while (1)
+    {
+        _delay_ms(1000);
+
+        temp = bme280_readTemperature(1);
+        pressure = bme280_readPressure(1);
+        humidity = bme280_readHumidity(1);
+
+        char out[10];
+        dtostrf(temp, 3, 1, out);
+        uart_putstr("T");
+        uart_putstr(out);
+        uart_putstr("\r\n");
+        dtostrf(pressure, 3, 1, out);
+        uart_putstr("P");
+        uart_putstr(out);
+        uart_putstr("\r\n");
+        dtostrf(humidity, 3, 1, out);
+        uart_putstr("H");
+        uart_putstr(out);
+        uart_putstr("\r\n");
+    }
+
+    return 0;
+}

src/sensor_bme280.c

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+#include "sensor_bme280.h"
+#include "bme280.h"
+#include "i2c.h"
+
+#include <util/delay.h>
+
+/**
+ * Checks whether the bme280 is connected to the i2c bus
+ * Returns 0 if success, 1 if error
+ */
+sensor_status check_sensor(void) {
+    i2c_init();
+    i2c_start((0x76 << 1) | 0x00);
+    i2c_byte(0xD0);
+    i2c_stop();
+
+    _delay_us(10);
+    i2c_start((0x76 << 1) | 0x01);
+    uint8_t ret = i2c_readNAck();
+    i2c_stop();
+
+    _delay_us(100);
+    i2c_start((0x76 << 1) | 0x00);
+    i2c_byte(BME280_REGISTER_SOFTRESET);
+    i2c_byte(0xB6);
+    i2c_stop();
+
+    if(ret == 0x60) {
+        return SENSOR_OK;
+    } else {
+        return SENSOR_NOT_FOUND;
+    }
+}

src/sensor_bme280.h

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+#pragma once
+
+typedef enum {
+    SENSOR_OK,
+    SENSOR_NOT_FOUND,
+} sensor_status;
+
+sensor_status check_sensor(void);

test/README

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+
+This directory is intended for PlatformIO Test Runner and project tests.
+
+Unit Testing is a software testing method by which individual units of
+source code, sets of one or more MCU program modules together with associated
+control data, usage procedures, and operating procedures, are tested to
+determine whether they are fit for use. Unit testing finds problems early
+in the development cycle.
+
+More information about PlatformIO Unit Testing:
+- https://docs.platformio.org/en/latest/advanced/unit-testing/index.html