Updates along with SDK1.3.0 release (#181)

Bug fixes and new examples

Co-authored-by: Paulo Marques <pm@quant-insight.com>
Co-authored-by: martin <admin@crossleys.biz>
Co-authored-by: matiasilva <matias.silva@raspberrypi.com>
Co-authored-by: Uri Shaked <uri@urishaked.com>
Co-authored-by: Diego Solano <diegosolano@gmail.com>
Co-authored-by: Andrew Scheller <andrew.scheller@raspberrypi.com>
Co-authored-by: Adrian Hesketh <a-h@users.noreply.github.com>
Co-authored-by: Emircan Gündoğdu <58917386+emircangun@users.noreply.github.com>
Co-authored-by: Josef Wegner <80200012+josefwegner@users.noreply.github.com>
Co-authored-by: pmarques-dev <72901351+pmarques-dev@users.noreply.github.com>
Co-authored-by: Paulo Marques <pm@quant-insight.com>
Co-authored-by: mjcross <mjcross@users.noreply.github.com>
Co-authored-by: martin <admin@crossleys.biz>

i2c/mcp9808_i2c/CMakeLists.txt

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+add_executable(mcp9808_i2c
+        mcp9808_i2c.c
+        )
+
+# pull in common dependencies and additional i2c hardware support
+target_link_libraries(mcp9808_i2c pico_stdlib hardware_i2c)
+
+# create map/bin/hex file etc.
+pico_add_extra_outputs(mcp9808_i2c)
+
+# add url via pico_set_program_url
+example_auto_set_url(mcp9808_i2c)

i2c/mcp9808_i2c/README.adoc

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+= Attaching a MCP9808 digital temperature sensor via I2C
+
+This example code shows how to interface the Raspberry Pi Pico to the MCP9808 digital temperature sensor board. 
+======
+This example reads the ambient temperature value each second from the sensor and sets upper, lower and critical limits for the temperature and checks if alerts need to be raised. The CONFIG register can also be used to check for an alert if the critical temperature is surpassed.
+======
+
+== Wiring information
+
+Wiring up the device requires 4 jumpers, to connect VDD, GND, SDA and SCL. The example here uses I2C port 0, which is assigned to GPIO 4 (SDA) and 5 (SCL) in software. Power is supplied from the VSYS pin.
+
+
+
+[[mcp9808_i2c_wiring]]
+[pdfwidth=75%]
+.Wiring Diagram for MCP9808.
+image::mcp9808_i2c.png[]
+
+== List of Files
+
+CMakeLists.txt:: CMake file to incorporate the example in to the examples build tree.
+mcp9808_i2c.c:: The example code.
+
+== Bill of Materials
+
+.A list of materials required for the example
+[[mcp9808-bom-table]]
+[cols=3]
+|===
+| *Item* | *Quantity* | Details
+| Breadboard | 1 | generic part
+| Raspberry Pi Pico | 1 | https://www.raspberrypi.com/products/raspberry-pi-pico/
+| MCP9808 board| 1 | https://www.adafruit.com/product/1782
+| M/M Jumper wires | 4 | generic part
+|===
+
+

i2c/mcp9808_i2c/mcp9808_i2c.c

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+/**
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include "pico/stdlib.h"
+#include "pico/binary_info.h"
+#include "hardware/i2c.h"
+
+/* Example code to talk to a MCP9808 ±0.5°C Digital temperature Sensor
+   
+   This reads and writes to registers on the board. 
+
+   Connections on Raspberry Pi Pico board, other boards may vary.
+
+   GPIO PICO_DEFAULT_I2C_SDA_PIN (On Pico this is GP4 (physical pin 6)) -> SDA on MCP9808 board
+   GPIO PICO_DEFAULT_I2C_SCK_PIN (On Pico this is GP5 (physcial pin 7)) -> SCL on MCP9808 board
+   Vsys (physical pin 39) -> VDD on MCP9808 board
+   GND (physical pin 38)  -> GND on MCP9808 board
+
+*/
+//The bus address is determined by the state of pins A0, A1 and A2 on the MCP9808 board
+static uint8_t ADDRESS = 0x18;
+
+//hardware registers
+
+const uint8_t REG_POINTER = 0x00;
+const uint8_t REG_CONFIG = 0x01;
+const uint8_t REG_TEMP_UPPER = 0x02;
+const uint8_t REG_TEMP_LOWER = 0x03;
+const uint8_t REG_TEMP_CRIT = 0x04;
+const uint8_t REG_TEMP_AMB = 0x05;
+const uint8_t REG_RESOLUTION = 0x08;
+
+
+void mcp9808_check_limits(uint8_t upper_byte) {
+
+    // Check flags and raise alerts accordingly 
+    if ((upper_byte & 0x40) == 0x40) { //TA > TUPPER
+        printf("Temperature is above the upper temperature limit.\n");
+    }
+    if ((upper_byte & 0x20) == 0x20) { //TA < TLOWER
+        printf("Temperature is below the lower temperature limit.\n");
+    }
+    if ((upper_byte & 0x80) == 0x80) { //TA > TCRIT
+        printf("Temperature is above the critical temperature limit.\n");
+    }
+}
+
+float mcp9808_convert_temp(uint8_t upper_byte, uint8_t lower_byte) {
+
+    float temperature;
+
+
+    //Check if TA <= 0°C and convert to denary accordingly
+    if ((upper_byte & 0x10) == 0x10) {
+        upper_byte = upper_byte & 0x0F;
+        temperature = 256 - (((float) upper_byte * 16) + ((float) lower_byte / 16));
+    } else {
+        temperature = (((float) upper_byte * 16) + ((float) lower_byte / 16));
+
+    }
+    return temperature;
+}
+
+#ifdef i2c_default
+void mcp9808_set_limits() {
+
+    //Set an upper limit of 30°C for the temperature
+    uint8_t upper_temp_msb = 0x01;
+    uint8_t upper_temp_lsb = 0xE0;
+
+    //Set a lower limit of 20°C for the temperature
+    uint8_t lower_temp_msb = 0x01;
+    uint8_t lower_temp_lsb = 0x40;
+
+    //Set a critical limit of 40°C for the temperature
+    uint8_t crit_temp_msb = 0x02;
+    uint8_t crit_temp_lsb = 0x80;
+
+    uint8_t buf[3];
+    buf[0] = REG_TEMP_UPPER;
+    buf[1] = upper_temp_msb;
+    buf[2] = upper_temp_lsb;
+    i2c_write_blocking(i2c_default, ADDRESS, buf, 3, false);
+
+    buf[0] = REG_TEMP_LOWER;
+    buf[1] = lower_temp_msb;
+    buf[2] = lower_temp_lsb;
+    i2c_write_blocking(i2c_default, ADDRESS, buf, 3, false);
+
+    buf[0] = REG_TEMP_CRIT;
+    buf[1] = crit_temp_msb;
+    buf[2] = crit_temp_lsb;;
+    i2c_write_blocking(i2c_default, ADDRESS, buf, 3, false);
+}
+#endif
+
+int main() {
+
+    stdio_init_all();
+
+#if !defined(i2c_default) || !defined(PICO_DEFAULT_I2C_SDA_PIN) || !defined(PICO_DEFAULT_I2C_SCL_PIN)
+#warning i2c/mcp9808_i2c example requires a board with I2C pins
+    puts("Default I2C pins were not defined");
+#else
+    printf("Hello, MCP9808! Reading raw data from registers...\n");
+
+    // This example will use I2C0 on the default SDA and SCL pins (4, 5 on a Pico)
+    i2c_init(i2c_default, 400 * 1000);
+    gpio_set_function(PICO_DEFAULT_I2C_SDA_PIN, GPIO_FUNC_I2C);
+    gpio_set_function(PICO_DEFAULT_I2C_SCL_PIN, GPIO_FUNC_I2C);
+    gpio_pull_up(PICO_DEFAULT_I2C_SDA_PIN);
+    gpio_pull_up(PICO_DEFAULT_I2C_SCL_PIN);
+    // Make the I2C pins available to picotool
+    bi_decl(bi_2pins_with_func(PICO_DEFAULT_I2C_SDA_PIN, PICO_DEFAULT_I2C_SCL_PIN, GPIO_FUNC_I2C));
+
+    mcp9808_set_limits();
+
+    uint8_t buf[2];
+    uint16_t upper_byte;
+    uint16_t lower_byte;
+
+    float temperature;
+
+    while (1) {
+        // Start reading ambient temperature register for 2 bytes
+        i2c_write_blocking(i2c_default, ADDRESS, &REG_TEMP_AMB, 1, true);
+        i2c_read_blocking(i2c_default, ADDRESS, buf, 2, false);
+
+        upper_byte = buf[0];
+        lower_byte = buf[1];
+
+        //isolates limit flags in upper byte
+        mcp9808_check_limits(upper_byte & 0xE0);
+
+        //clears flag bits in upper byte
+        temperature = mcp9808_convert_temp(upper_byte & 0x1F, lower_byte);
+        printf("Ambient temperature: %.4f°C\n", temperature);
+
+        sleep_ms(1000);
+    }
+#endif
+}