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adc/microphone_adc - Read analog values from a microphone and plot the measured sound amplitude. i2c/bmp280_i2c - Read and convert temperature and pressure data from a BMP280 sensor, attached to an I2C bus. i2c/lis3dh_i2c - Read acceleration and temperature value from a LIS3DH sensor via I2C i2c/mcp9808_i2c - Read temperature, set limits and raise alerts when limits are surpassed. i2c/mma8451_i2c - Read acceleration from a MMA8451 accelerometer and set range and precision for the data. i2c/mpl3115a2_i2c - Interface with an MPL3115A2 altimeter, exploring interrupts and advanced board features, via I2C. i2c/oled_i2c - Convert and display a bitmap on a 128x32 SSD1306-driven OLED display i2c/pa1010d_i2c - Read GPS location data, parse and display data via I2C. i2c/pcf8523_i2c - Read time and date values from a real time clock. Set current time and alarms on it. uart/lcd_uart - Display text and symbols on a 16x02 RGB LCD display via UART
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= Attaching a 16x2 LCD via TTL
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This example code shows how to interface the Raspberry Pi Pico to one of the very common 16x2 LCD character displays. Due to the large number of pins these displays use, they are commonly used with extra drivers or backpacks. In this example, we will use an Adafruit LCD display backpack, which supports communication over USB or TTL. A monochrome display with an RGB backlight is also used, but the backpack is compatible with monochrome backlight displays too. There is another example that uses I2C to control a 16x2 display.
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The backpack processes a set of commands that are documented https://learn.adafruit.com/usb-plus-serial-backpack/command-reference[here] and preceded by the "special" byte 0xFE. The backpack does the ASCII character conversion and even supports custom character creation. In this example, we use the Pico's primary UART (uart0) to read characters from our computer and send them via the other UART (uart1) to print them onto the LCD. We also define a special startup sequence and vary the display's backlight color.
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NOTE: You can change where stdio output goes (Pico's USB, uart0 or both) with CMake directives. The CMakeLists.txt file shows how to enable both.
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== Wiring information
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Wiring up the backpack to the Pico requires 3 jumpers, to connect VCC (3.3v), GND, TX. The example here uses both of the Pico's UARTs, one (uart0) for stdio and the other (uart1) for communication with the backpack. Pin 8 is used as the TX pin. Power is supplied from the 3.3V pin. To connect the backpack to the display, it is common practice to solder it onto the back of the display, or during the prototyping stage to use the same parallel lanes on a breadboard.
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NOTE: While this display will work at 3.3V, it will be quite dim. Using a 5V source will make it brighter.
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[[lcd_uart_wiring]]
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[pdfwidth=75%]
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.Wiring Diagram for LCD with TTL backpack.
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image::lcd_uart_bb.png[]
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== List of Files
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CMakeLists.txt:: CMake file to incorporate the example in to the examples build tree.
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lcd_uart.c:: The example code.
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== Bill of Materials
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.A list of materials required for the example
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[[lcd_uart-bom-table]]
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[cols=3]
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|===
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| *Item* | *Quantity* | Details
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| Breadboard | 1 | generic part
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| Raspberry Pi Pico | 1 | https://www.raspberrypi.com/products/raspberry-pi-pico/
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| 16x2 RGB LCD panel 3.3v | 1 | generic part, https://www.adafruit.com/product/398[available on Adafruit]
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| 16x2 LCD backpack | 1 | https://www.adafruit.com/product/781[from Adafruit]
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| M/M Jumper wires | 3 | generic part
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|===
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