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/mma8451_i2c/CMakeLists.txt

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+add_executable(mma8451_i2c
+        mma8451_i2c.c
+        )
+# pull in common dependencies and additional i2c hardware support
+target_link_libraries(mma8451_i2c pico_stdlib hardware_i2c)
+
+# create map/bin/hex file etc.
+pico_add_extra_outputs(mma8451_i2c)
+
+# add url via pico_set_program_url
+example_auto_set_url(mma8451_i2c)

i2c/mma8451_i2c/README.adoc

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+= Attaching a MMA8451 3-axis digital accelerometer via I2C
+
+This example code shows how to interface the Raspberry Pi Pico to the MMA8451 digital accelerometer sensor board. 
+======
+This example reads and displays the acceleration values of the board in the 3 axis. It also allows the user to set the trade-off between the range and precision based on the values they require. Values often have an offset which can be accounted for by writing to the offset correction registers. The datasheet for the sensor can be found at https://cdn-shop.adafruit.com/datasheets/MMA8451Q-1.pdf for additional information.
+======
+
+== Wiring information
+
+Wiring up the device requires 4 jumpers, to connect VIN, 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.
+
+
+
+[[mma8451_i2c_wiring]]
+[pdfwidth=75%]
+.Wiring Diagram for MMA8451.
+image::mma8451_i2c.png[]
+
+== List of Files
+
+CMakeLists.txt:: CMake file to incorporate the example in to the examples build tree.
+mma8451_i2c.c:: The example code.
+
+== Bill of Materials
+
+.A list of materials required for the example
+[[mma8451-bom-table]]
+[cols=3]
+|===
+| *Item* | *Quantity* | Details
+| Breadboard | 1 | generic part
+| Raspberry Pi Pico | 1 | https://www.raspberrypi.com/products/raspberry-pi-pico/
+| MMA8451 board| 1 | https://www.adafruit.com/product/2019
+| M/M Jumper wires | 4 | generic part
+|===
+
+

i2c/mma8451_i2c/mma8451_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 MMA8451 triple-axis accelerometer.
+   
+   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 MMA8451 board
+   GPIO PICO_DEFAULT_I2C_SCK_PIN (On Pico this is GP5 (physcial pin 7)) -> SCL on MMA8451 board
+   VSYS (physical pin 39) -> VDD on MMA8451 board
+   GND (physical pin 38)  -> GND on MMA8451 board
+
+*/
+
+const uint8_t ADDRESS = 0x1D;
+
+//hardware registers
+
+const uint8_t REG_X_MSB = 0x01;
+const uint8_t REG_X_LSB = 0x02;
+const uint8_t REG_Y_MSB = 0x03;
+const uint8_t REG_Y_LSB = 0x04;
+const uint8_t REG_Z_MSB = 0x05;
+const uint8_t REG_Z_LSB = 0x06;
+const uint8_t REG_DATA_CFG = 0x0E;
+const uint8_t REG_CTRL_REG1 = 0x2A;
+
+// Set the range and precision for the data 
+const uint8_t range_config = 0x01; // 0x00 for ±2g, 0x01 for ±4g, 0x02 for ±8g
+const float count = 2048; // 4096 for ±2g, 2048 for ±4g, 1024 for ±8g
+
+uint8_t buf[2];
+
+float mma8451_convert_accel(uint16_t raw_accel) {
+    float acceleration;
+    // Acceleration is read as a multiple of g (gravitational acceleration on the Earth's surface)
+    // Check if acceleration < 0 and convert to decimal accordingly
+    if ((raw_accel & 0x2000) == 0x2000) {
+        raw_accel &= 0x1FFF;
+        acceleration = (-8192 + (float) raw_accel) / count;
+    } else {
+        acceleration = (float) raw_accel / count;
+    }
+    acceleration *= 9.81f;
+    return acceleration;
+}
+
+#ifdef i2c_default
+void mma8451_set_state(uint8_t state) {
+    buf[0] = REG_CTRL_REG1;
+    buf[1] = state; // Set RST bit to 1
+    i2c_write_blocking(i2c_default, ADDRESS, buf, 2, 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/mma8451_i2c example requires a board with I2C pins
+    puts("Default I2C pins were not defined");
+#else
+    printf("Hello, MMA8451! 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));
+
+    float x_acceleration;
+    float y_acceleration;
+    float z_acceleration;
+
+    // Enable standby mode
+    mma8451_set_state(0x00);
+
+    // Edit configuration while in standby mode
+    buf[0] = REG_DATA_CFG;
+    buf[1] = range_config;
+    i2c_write_blocking(i2c_default, ADDRESS, buf, 2, false);
+
+    // Enable active mode
+    mma8451_set_state(0x01);
+
+    while (1) {
+
+        // Start reading acceleration registers for 2 bytes
+        i2c_write_blocking(i2c_default, ADDRESS, &REG_X_MSB, 1, true);
+        i2c_read_blocking(i2c_default, ADDRESS, buf, 2, false);
+        x_acceleration = mma8451_convert_accel(buf[0] << 6 | buf[1] >> 2);
+
+        i2c_write_blocking(i2c_default, ADDRESS, &REG_Y_MSB, 1, true);
+        i2c_read_blocking(i2c_default, ADDRESS, buf, 2, false);
+        y_acceleration = mma8451_convert_accel(buf[0] << 6 | buf[1] >> 2);
+
+        i2c_write_blocking(i2c_default, ADDRESS, &REG_Z_MSB, 1, true);
+        i2c_read_blocking(i2c_default, ADDRESS, buf, 2, false);
+        z_acceleration = mma8451_convert_accel(buf[0] << 6 | buf[1] >> 2);
+
+        // Display acceleration values 
+        printf("ACCELERATION VALUES: \n");
+        printf("X acceleration: %.6fms^-2\n", x_acceleration);
+        printf("Y acceleration: %.6fms^-2\n", y_acceleration);
+        printf("Z acceleration: %.6fms^-2\n", z_acceleration);
+
+        sleep_ms(500);
+
+        // Clear terminal 
+        printf("\e[1;1H\e[2J");
+    }
+
+#endif
+}