Qwiic Carrier Board Hookup Guide

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Introduction

The MicroMod Qwiic Carrier Board can be used to rapidly prototype with other Qwiic devices; it is available in either a single or double mounting configuration. Just like other MicroMod Carrier Boards, users are free to develop with MicroMod Processor Board of their choice.

SparkFun MicroMod Qwiic Carrier Board - Single

SparkFun MicroMod Qwiic Carrier Board - Single

DEV-17723
$9.95
SparkFun MicroMod Qwiic Carrier Board - Double

SparkFun MicroMod Qwiic Carrier Board - Double

DEV-17724
$11.95

For a quick overview, check out our product video showcasing the MicroMod Qwiic carrier boards:

Required Materials

To get started, users will need a few of items listed below. (You may already have a some of these items; read through the guide and modify your cart accordingly.)

MicroMod Processor Board

Like other MicroMod Carrier Boards, a Processor Board is required for the product to operate. Users will need a Processor Board (of their choice) to attach to the MicroMod M.2 connector; since, one is not included with this product. Below, are few options:

SparkFun MicroMod Artemis Processor

SparkFun MicroMod Artemis Processor

DEV-16401
$14.95
SparkFun MicroMod ESP32 Processor

SparkFun MicroMod ESP32 Processor

WRL-16781
$14.95
SparkFun MicroMod RP2040 Processor

SparkFun MicroMod RP2040 Processor

DEV-17720
$11.95
SparkFun MicroMod Update Tool

SparkFun MicroMod Update Tool

DEV-17725
$4.95

Required Hardware

A Phillips screw driver is necessary to attach the Processor board to the Carrier Board. Additionally, a USB-C cable is needed to connect the Carrier Board to a computer.

USB 3.1 Cable A to C - 3 Foot

USB 3.1 Cable A to C - 3 Foot

CAB-14743
$4.95
2
SparkFun Mini Screwdriver

SparkFun Mini Screwdriver

TOL-09146
$0.95
3

Optional Hardware

To connect Qwiic breakout boards for your MicroMod project, Qwiic cables are required. Users can also attach the Qwiic devices with 4-40 screws or stacked them with standoffs.

SparkFun Qwiic Cable Kit

SparkFun Qwiic Cable Kit

KIT-15081
$7.95
10
Flexible Qwiic Cable - 100mm

Flexible Qwiic Cable - 100mm

PRT-17259
$1.50
Screw - Phillips Head (1/4", 4-40, 10 pack)

Screw - Phillips Head (1/4", 4-40, 10 pack)

PRT-10453
$1.50
Standoff - Metal Hex (4-40; 3/8"; 10 pack)

Standoff - Metal Hex (4-40; 3/8"; 10 pack)

PRT-10463
$3.95

A single-cell Lithium-ion battery can be connected to the Qwiic Carrier Board for portability.

Lithium Ion Battery - 400mAh

Lithium Ion Battery - 400mAh

PRT-13851
$4.95
9
Lithium Ion Battery - 2Ah

Lithium Ion Battery - 2Ah

PRT-13855
$12.95
7
Lithium Ion Battery - 1Ah

Lithium Ion Battery - 1Ah

PRT-13813
$9.95
7
Lithium Ion Battery - 110mAh

Lithium Ion Battery - 110mAh

PRT-13853
$4.95
2

To modify the jumpers, users will need soldering equipment and/or a knife.

Solder Lead Free - 100-gram Spool

Solder Lead Free - 100-gram Spool

TOL-09325
$8.95
7
Chip Quik No-Clean Flux Pen  - 10mL

Chip Quik No-Clean Flux Pen - 10mL

TOL-14579
$7.95
3
Weller WLC100 Soldering Station

Weller WLC100 Soldering Station

TOL-14228
$44.95
2
Hobby Knife

Hobby Knife

TOL-09200
$2.95
2

Suggested Reading

The MicroMod ecosystem is a unique way to allow users to customize their project to their needs. The Qwiic connect system is a simple method for interfacing with I2C devices. Click on the banners below for more information on each system.

MicroMod Logo

Qwiic Logo

For users who aren't familiar with the following concepts, we also recommend reading the following tutorials before continuing.

Serial Communication

Asynchronous serial communication concepts: packets, signal levels, baud rates, UARTs and more!

I2C

An introduction to I2C, one of the main embedded communications protocols in use today.

Getting Started with MicroMod

Dive into the world of MicroMod - a compact interface to connect a microcontroller to various peripherals via the M.2 Connector!

Designing with MicroMod

This tutorial will walk you through the specs of the MicroMod processor and carrier board as well as the basics of incorporating the MicroMod form factor into your own PCB designs!

Installing an Arduino Library

How do I install a custom Arduino library? It's easy! This tutorial will go over how to install an Arduino library using the Arduino Library Manager. For libraries not linked with the Arduino IDE, we will also go over manually installing an Arduino library.

Installing Arduino IDE

A step-by-step guide to installing and testing the Arduino software on Windows, Mac, and Linux.

Installing Board Definitions in the Arduino IDE

How do I install a custom Arduino board/core? It's easy! This tutorial will go over how to install an Arduino board definition using the Arduino Board Manager. We will also go over manually installing third-party cores, such as the board definitions required for many of the SparkFun development boards.

Hardware Overview

This section will cover the various hardware components and solder jumpers on the MicroMod Qwiic Carrier Board. It will also review the connections of the M.2 connector and how it interfaces with a MicroMod Processor.

Board Dimensions

The Qwiic Carrier Board dimensions are:

  • Single: 3.15" x 1.40" (80.00mm x 35.56mm)
  • Double: 4.10" x 1.40" (109.22mm x 35.56mm)

MicroMod Qwiic carrier board dimensions - single

MicroMod Qwiic carrier board dimensions - double
Dimensions of the MicroMod Qwiic Carrier Board. (Click to enlarge)

The boards also include mounting holes and inserts for a standard 4-40 screw. The inserts are arranged to mount, attach, and/or stack compatible (1" x 1") Qwiic boards.

Photo highlighting inserts layout - single
Photo highlighting inserts layout - double

Mounting areas on the MicroMod Qwiic Carrier Board to attach Qwiic devices. (Click to enlarge)

Common Components

Most SparkFun MicroMod Carrier Boards will have some common components and all MicroMod Carrier Boards will have the keyed M.2 MicroMod connector for a Processor board. The photo and list below outline the common components between the Qwiic carrier board and other MicroMod Carrier Boards.

  • M.2 MicroMod Connector - This special keyed M.2 connector lets you install your MicroMod Processor of choice to the Qwiic Carrier Board.
  • USB-C Connector - Connect to your computer to program your processor and provide power to the board.
  • 3.3V Regulator - Provides a regulated 3.3V and sources up to 1A.
  • Qwiic Connectors - The standard Qwiic connectors to connect other Qwiic devices for your MicroMod project.
  • Boot/Reset Buttons - Push buttons to enter boot mode on processors and to reset your MicroMod circuit.

Annotated photo for common components on the Qwiic carrier board
Common MicroMod components featured on the MicroMod Qwiic Carrier Board. (Click to enlarge)

Battery Charger

The board also has a MCP73831 Single-Cell Lithium-Ion/Lithium-Polymer Charge IC so you can charge an attached single-cell LiPo battery. The charge IC receives power from the USB connection and can source up to 450mA to charge an attached battery.

Photo highlighting the charging circuit
Batery charger for the MicroMod Qwiic Carrier Board. (Click to enlarge)

Status LEDs

The carrier board has two status LEDs:

  • PWR - This LED indicates when 3.3V power is available top the board.
  • CHG - This LED indicates the status of the charging circuit operation.

Photo highlighting the status LEDs
Status LEDs on the MicroMod Qwiic Carrier Board. (Click to enlarge)

Solder Jumpers

Users who have never worked with soldering jumpers and cutting PCB traces before (or for a quick refresher), check out our How to Work with Solder Jumpers and PCB Traces tutorial for detailed instructions and tips.

There are four adjustable solder jumpers on the MicroMod Qwiic Carrier Board labeled MEAS, BYP, 3.3V_VE and 3.3V. The table below briefly outlines their functionalities:

Jumper Name/Label Description Default State
Measure/MEAS Open this jumper to probe the current draw at the 3.3V output of the regulator. For help measuring current, take a look at our How to Use a Multimeter tutorial. CLOSED
Bypass/BYP The "penny-in-the-fuse" jumper. Bypasses the 6V/2A fuse and nets VIN and V_USB together. Close only if you know what you are doing! OPEN
Voltage Regulator Enable/VE Voltage regulator control. Close this jumper to control the VREG in low-power applications. OPEN
3.3V LED Power/3V3 LED Connects the 3.3V LED to 3.3V via a 1K Ohm resistor. Open to disable the LED. CLOSED

Jumpers
Jumpers on the MicroMod Qwiic carrier board. (Click to enlarge)

MicroMod Pinout

Since this Carrier Board is designed to work with all of the MicroMod Processors we've included the table below to outline which pins are used so, if you would like, you can compare them to the pinout tables in their respective Hookup Guides.

AUDIO UART GPIO/BUS I2C SDIO SPI Dedicated
Function Bottom
Pin
   Top   
Pin
Function
(Not Connected) 75 GND
3.3V 74 73 G5 / BUS5
RTC_3V_BATT 72 71 G6 / BUS6
SPI_CS1# SDIO_DATA3 (I/O) 70 69 G7 / BUS7
SDIO_DATA2 (I/O) 68 67 G8
SDIO_DATA1 (I/O) 66 65 G9 ADC_D- CAM_HSYNC
SPI_CIPO1 SDIO_DATA0 (I/O) 64 63 G10 ADC_D+ CAM_VSYNC
SPI COPI1 SDIO_CMD (I/O) 62 61 SPI_CIPO (I)
SPI SCK1 SDIO_SCK (O) 60 59 SPI_COPI (O) LED_DAT
AUD_MCLK (O) 58 57 SPI_SCK (O) LED_CLK
CAM_MCLK PCM_OUT I2S_OUT AUD_OUT 56 55 SPI_CS#
CAM_PCLK PCM_IN I2S_IN AUD_IN 54 53 I2C_SCL1 (I/O)
PDM_DATA PCM_SYNC I2S_WS AUD_LRCLK 52 51 I2C_SDA1 (I/O)
PDM_CLK PCM_CLK I2S_SCK AUD_BCLK 50 49 BATT_VIN / 3 (I - ADC) (0 to 3.3V)
G4 / BUS4 48 47 PWM1
G3 / BUS3 46 45 GND
G2 / BUS2 44 43 CAN_TX
G1 / BUS1 42 41 CAN_RX
G0 / BUS0 40 39 GND
A1 38 37 USBHOST_D-
GND 36 35 USBHOST_D+
A0 34 33 GND
PWM0 32 31 Module Key
Module Key 30 29 Module Key
Module Key 28 27 Module Key
Module Key 26 25 Module Key
Module Key 24 23 SWDIO
UART_TX2 (O) 22 21 SWDCK
UART_RX2 (I) 20 19 UART_RX1 (I)
CAM_TRIG D1 18 17 UART_TX1 (0)
I2C_INT# 16 15 UART_CTS1 (I)
I2C_SCL (I/0) 14 13 UART_RTS1 (O)
I2C_SDA (I/0) 12 11 BOOT (I - Open Drain)
D0 10 9 USB_VIN
SWO G11 8 7 GND
RESET# (I - Open Drain) 6 5 USB_D-
3.3V_EN 4 3 USB_D+
3.3V 2 1 GND
Signal Group Signal I/O Description Voltage
Power 3.3V I 3.3V Source 3.3V
GND Return current path 0V
USB_VIN I USB VIN compliant to USB 2.0 specification.
Connect to pins on Processor Board that require 5V for USB functionality.
4.8-5.2V
RTC_3V_BATT I 3V provided by external coin cell or mini battery. Max draw = 100μA.
Connect to pins maintaining an RTC during power loss. Can be left NC.
3V
3.3V_EN O Controls the carrier board's main voltage regulator. Voltage above 1V will enable 3.3V power path. 3.3V
BATT_VIN/3 I Carrier board raw voltage over 3. 1/3 resistor divider is implemented on carrier board.
Amplify the analog signal as needed for full 0-3.3V range
3.3V
Reset Reset I Input to processor. Open drain with pullup on processor board. Pulling low resets processor. 3.3V
Boot I Input to processor. Open drain with pullup on processor board. Pulling low puts processor into special boot mode. Can be left NC. 3.3V
USB USB_D± I/O USB Data ±. Differential serial data interface compliant to USB 2.0 specification. If UART is required for programming, USB± must be routed to a USB-to-serial conversion IC on the processor board.
USB Host USBHOST_D± I/O For processors that support USB Host Mode. USB Data±. Differential serial data interface compliant to USB 2.0 specification. Can be left NC.
CAN CAN_RX I CAN Bus receive data. 3.3V
CAN_TX O CAN Bus transmit data. 3.3V
UART UART_RX1 I UART receive data. 3.3V
UART_TX1 O UART transmit data. 3.3V
UART_RTS1 O UART request to send. 3.3V
UART_CTS1 I UART clear to send. 3.3V
UART_RX2 I 2nd UART receive data. 3.3V
UART_TX2 O 2nd UART transmit data. 3.3V
I2C I2C_SCL I/O I2C clock. Open drain with pullup on carrier board. 3.3V
I2C_SDA I/O I2C data. Open drain with pullup on carrier board 3.3V
I2C_INT# I Interrupt notification from carrier board to processor. Open drain with pullup on carrier board. Active LOW 3.3V
I2C_SCL1 I/O 2nd I2C clock. Open drain with pullup on carrier board. 3.3V
I2C_SDA1 I/O 2nd I2C data. Open drain with pullup on carrier board. 3.3V
SPI SPI_COPI O SPI Controller Output/Peripheral Input. 3.3V
SPI_CIPO I SPI Controller Input/Peripheral Output. 3.3V
SPI_SCK O SPI Clock. 3.3V
SPI_CS# O SPI Chip Select. Active LOW. Can be routed to GPIO if hardware CS is unused. 3.3V
SPI/SDIO SPI_SCK1/SDIO_CLK O 2nd SPI Clock. Secondary use is SDIO Clock. 3.3V
SPI_COPI1/SDIO_CMD I/O 2nd SPI Controller Output/Peripheral Input. Secondary use is SDIO command interface. 3.3V
SPI_CIPO1/SDIO_DATA0 I/O 2nd SPI Peripheral Input/Controller Output. Secondary use is SDIO data exchange bit 0. 3.3V
SDIO_DATA1 I/O SDIO data exchange bit 1. 3.3V
SDIO_DATA2 I/O SDIO data exchange bit 2. 3.3V
SPI_CS1/SDIO_DATA3 I/O 2nd SPI Chip Select. Secondary use is SDIO data exchange bit 3. 3.3V
Audio AUD_MCLK O Audio master clock. 3.3V
AUD_OUT/PCM_OUT/I2S_OUT/CAM_MCLK O Audio data output. PCM synchronous data output. I2S serial data out. Camera master clock. 3.3V
AUD_IN/PCM_IN/I2S_IN/CAM_PCLK I Audio data input. PCM syncrhonous data input. I2S serial data in. Camera periphperal clock. 3.3V
AUD_LRCLK/PCM_SYNC/I2S_WS/PDM_DATA I/O Audio left/right clock. PCM syncrhonous data SYNC. I2S word select. PDM data. 3.3V
AUD_BCLK/PCM_CLK/I2S_CLK/PDM_CLK O Audio bit clock. PCM clock. I2S continuous serial clock. PDM clock. 3.3V
SWD SWDIO I/O Serial Wire Debug I/O. Connect if processor board supports SWD. Can be left NC. 3.3V
SWDCK I Serial Wire Debug clock. Connect if processor board supports SWD. Can be left NC. 3.3V
ADC A0 I Analog to digital converter 0. Amplify the analog signal as needed to enable full 0-3.3V range. 3.3V
A1 I Analog to digital converter 1. Amplify the analog signal as needed to enable full 0-3.3V range. 3.3V
PWM PWM0 O Pulse width modulated output 0. 3.3V
PWM1 O Pulse width modulated output 1. 3.3V
Digital D0 I/O General digital input/output pin. 3.3V
D1/CAM_TRIG I/O General digital input/output pin. Camera trigger. 3.3V
General/Bus G0/BUS0 I/O General purpose pins. Any unused processor pins should be assigned to Gx with ADC + PWM capable pins given priority (0, 1, 2, etc.) positions. The intent is to guarantee PWM, ADC and Digital Pin functionality on respective ADC/PWM/Digital pins. Gx pins do not guarantee ADC/PWM function. Alternative use is pins can support a fast read/write 8-bit or 4-bit wide bus. 3.3V
G1/BUS1 I/O 3.3V
G2/BUS2 I/O 3.3V
G3/BUS3 I/O 3.3V
G4/BUS4 I/O 3.3V
G5/BUS5 I/O 3.3V
G6/BUS6 I/O 3.3V
G7/BUS7 I/O 3.3V
G8 I/O General purpose pin 3.3V
G9/ADC_D-/CAM_HSYNC I/O Differential ADC input if available. Camera horizontal sync. 3.3V
G10/ADC_D+/CAM_VSYNC I/O Differential ADC input if available. Camera vertical sync. 3.3V
G11/SWO I/O General purpose pin. Serial Wire Output 3.3V
M.2 Connector Pin# MicroMod Pin Name Board Connection Description
1 GND GND Ground plane.
2 3.3V 3.3V Regulated 3.3V via USB-C.
3 USB_D+ -- USB D+ connection for Processor Board.
4 3.3V_EN -- Voltage regulator enable input.
5 USB_D- -- USB D- connection for Processor Board.
6 RESET RESET Button Connected to RESET Button. Reset is active LOW
9 USB_VIN -- Input voltage from USB.
10 D0 D0 Digital I/O pin
11 BOOT BOOT Button Connected to BOOT Button. Boot is active LOW.
12 I2C_SDA Qwiic Connector - SDA I2C data signal for Qwiic devices.
14 I2C_SCL Qwiic Connector - SCL I2C clock signal for Qwiic devices.
16 I2C_INT INT I2C interrupt pin
18 D1 D1 Digital I/O pin
55 SPI_CS CS Chip Select.
57 SPI_SCK SCK SPI Clock signal.
59 SPI_COPI COPI SPI Controller Out/Peripheral In signal.
61 SPI_CIPO CIPO SPI Controller In/Peripheral Out signal.

Breakout Pins

The Qwiic Carrier Board features a 3.3V, a ground, seven I/O breakout pins. The functionality of these pins are detailed in the table above.

breakout pins
Breakout pins on the MicroMod Qwiic Carrier Board. (Click to enlarge)

Hardware Assembly

For those unfamiliar with the MicroMod ecosystem, be sure to review the Getting Started with MicroMod guide.

Getting Started with MicroMod

October 21, 2020

Dive into the world of MicroMod - a compact interface to connect a microcontroller to various peripherals via the M.2 Connector!

Processor Board

To get started with the Qwiic Carrier Board, users will need a compatible Processor. Insert the MicroMod Processor board into the M.2 socket at an angle, with its edge connector aligned to the matching slots.

Note: The dimensions of the Processor board's edge connector prevents it from mating with the slots of the M.2 socket in reverse. As an extra safeguard, the screw insert is spaced to only match the screw key of MicroMod Processor boards.

When inserted properly, the Processor board will rest at an angle:

MicroMod processor board inserted into the carrier board
Inserting a processor board into the M.2 socket on the MicroMod Qwiic Carrier Board. (Click to enlarge)

To secure the processor board, gently hold down on the board and attach the M.2 screw with a Phillip's head (PH0 or PH1) screw driver. Below, is an example of an assembled MicroMod system:

MicroMod processor board attached to the Qwiic carrier board
A processor board attached to the MicroMod Qwiic Carrier Board. (Click to enlarge)

Qwiic Devices

Screw inserts are available in either a single or double configuration to attach/mount 1" x 1" Qwiic devices to the Qwiic carrier board. The inserts are compatible with 4-40 screws; additionally, 4-40 3/8" standoffs can also be used to stack boards vertically.

To electronically connect the Qwiic devices to the Carrier Board, users will need Qwiic cables. For more information, check out our Qwiic ecosystem page.

Attaching Qwiic devices to single carrier board
Attaching Qwiic devices to double carrier board

Mounting and connecting Qwiic devices to the MicroMod Qwiic Carrier Board. (Click to enlarge)

Programming

To program the processor board utilized on the Qwiic Carrier Board; connect the board to a computer with a USB-C cable. Depending on the Processor board, user may need to install drivers (if they have not done so already).

Note: Make sure that the correct board definitions are installed in the Arduino IDE, for the selected Processor board. For help installing board definitions, use the MicroMod processor boards landing page and review the associated hookup guide for that hardware.

Installing Board Definitions in the Arduino IDE

September 9, 2020

How do I install a custom Arduino board/core? It's easy! This tutorial will go over how to install an Arduino board definition using the Arduino Board Manager. We will also go over manually installing third-party cores, such as the board definitions required for many of the SparkFun development boards.

USB connection
USB connection to the MicroMod Qwiic carrier board for programming the attached processor board. (Click to enlarge)

Example

Below is a simple demonstration of using the MicroMod Qwiic Carrier Board to create a bubble level, using an accelerometer and OLED display. Users will also need other parts and accessories; all parts besides the Qwiic carrier board are listed below:

SparkFun Qwiic Cable Kit

SparkFun Qwiic Cable Kit

KIT-15081
$7.95
10
SparkFun Micro OLED Breakout (Qwiic)

SparkFun Micro OLED Breakout (Qwiic)

LCD-14532
$16.95
6
SparkFun MicroMod ESP32 Processor

SparkFun MicroMod ESP32 Processor

WRL-16781
$14.95
USB 3.1 Cable A to C - 3 Foot

USB 3.1 Cable A to C - 3 Foot

CAB-14743
$4.95
2
SparkFun Mini Screwdriver

SparkFun Mini Screwdriver

TOL-09146
$0.95
3
Screw - Phillips Head (1/4", 4-40, 10 pack)

Screw - Phillips Head (1/4", 4-40, 10 pack)

PRT-10453
$1.50
Triple Axis Accelerometer Breakout - LIS2DH12 (Qwiic)

Triple Axis Accelerometer Breakout - LIS2DH12 (Qwiic)

SPX-15760
$6.95
Standoff - Metal Hex (4-40; 3/8"; 10 pack)

Standoff - Metal Hex (4-40; 3/8"; 10 pack)

PRT-10463
$3.95

Note: We have chosen the MicroMod ESP32 for the processor board for this demonstration; however, users are free to utilize the processor board of their choice.

Please note, that the sample code below is intended to program processor boards that are compatible with the Arduino IDE. Therefore, processor boards like the RP2040 are going to need extra effort to adapt the code (technical assistance for which, is not available).

Assembly

The assemble process is relatively straight forward. The primary thing that users need to pay attention to is the orientation of the OLED display relative to the axes of the accelerometer. The x-axis should point to the right of the OLED display and the y-axis should point to the top of the display (see images below).

Accelerometer attached to single carrier board
OLED display stacked above the acceleromter on the carrier board

Mounting and connecting the Qwiic devices to the MicroMod Qwiic Carrier Board. (Click to enlarge)

Some users may find it the movement of the bubble in the example code to be more intuitive if the OLED display is stacked above the accelerometer.

assembled demo
Don't forget to daisy-chain the boards together with Qwiic cables. (Click to enlarge)

Example Code

Users can download the example code here or by clicking the button below. Besides the RP2040 processor board, users only need to select the proper port and board from the board manager in the Arduino IDE before uploading the code.

The following sections break down the example code execution for users who might want to modify the code. Please note, as defined in our terms of service, that we do not provide technical assistance for any code modifications.

Dependencies

Below are the dependencies for the code including the libraries, pin definitions, and variable instantiations. The example code requires both the Micro OLED and LIS2DH12 Arduino libraries to be installed in the Arduino IDE.

Tip: While in the Arduino IDE, users can click the links in the code (i.e. //Click here to get the library: http://librarymanager/All#SparkFun_LIS2DH12) to pull up the required library in the library manager.

link pulling up the library manager
Clicking the link to pull up the required library in the Arduino IDE. (Click to enlarge)

Installing an Arduino Library

January 11, 2013

How do I install a custom Arduino library? It's easy! This tutorial will go over how to install an Arduino library using the Arduino Library Manager. For libraries not linked with the Arduino IDE, we will also go over manually installing an Arduino library.

Libraries and Pin Definitions

This section of the code contains the required libraries and pin definitions for the code.

language:c
#include <Wire.h>

// Accelerometer
//=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
#include "SparkFun_LIS2DH12.h" //Click here to get the library: http://librarymanager/All#SparkFun_LIS2DH12
SPARKFUN_LIS2DH12 accel;
//=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

// External Display
//=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
#include <SFE_MicroOLED.h> //Click here to get the library: http://librarymanager/All#SparkFun_Micro_OLED
//#include "icons.h"

#define PIN_RESET 7
#define DC_JUMPER 1
MicroOLED oled(PIN_RESET, DC_JUMPER);
//=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Variables

This section of the code instantiates most of the variables used in the code.

language:c
// Set target and dot size
int radiusLarge = 10; // Target area 2
int radiusSmall = 4;  // Target area 1
int radiusBubble = 2; // Bubble size

// Set initial roll and pitch measurement
double averagedRoll = 0.0;
double averagedPitch = 0.0;

Setup Loop

This section of the code runs the setup loop, which initializes the serial output, I2C connection, the OLED display operation, and the accelerometer operation and configuration.

language:c
void setup()
{
  // Initialize Output for Print Statements
  Serial.begin(115200);
  Serial.println("SparkFun Accel Example");

  // Initialize I2C Connection
  Wire.begin();
  //Wire.setClock(400000);

  beginDisplay(); //Check if an external Qwiic OLED is attached and display splash screen

  // Check for accelerometer
  if (accel.begin() == false)
  {
    Serial.println("Accelerometer not detected. Check address jumper and wiring. Freezing...");
    while (1)
      ;
  }

  // Set sample/data rate for accelerometer
  // The larger the avgAmount the faster we should read the sensor
  //accel.setDataRate(LIS2DH12_ODR_100Hz); //6 measurements a second
  accel.setDataRate(LIS2DH12_ODR_400Hz); //25 measurements a second
}
Setup Functions

These functions are executed in the setup loop, to initialize the OLED display I2C connection and display the splash screen.

language:c
// Ping an I2C address and see if it responds
bool isConnected(uint8_t deviceAddress)
{
  Wire.beginTransmission(deviceAddress);
  if (Wire.endTransmission() == 0)
    return true;
  return false;
}


void beginDisplay()
{
  // Connect to address display is on by pinging addresses
  // 0x3D is default on Qwiic board
  if (isConnected(0x3D) == true || isConnected(0x3C) == true)
  {
    //Init and display splash
    oled.begin();     // Initialize the OLED
    oled.display();   // Display splash screen
    delay(1200);
    oled.clear(PAGE); // Clear the display's internal memory

    oled.setCursor(15, 7); //x, y
    oled.setFontType(0); //Set font to smallest
    oled.print(F("Bubble"));
    oled.setCursor(19, 20); //x, y
    oled.print(F("Level"));

    oled.display();
    delay(1200);
  }
}

Main loop

This section of the code runs the main loop. The code retrieves roll and pitch calculation, clears the display buffer, displays the bubble and target circles or areas. If the position of the bubble is within the target are, the roll and pitch angles are displayed as X and Y coordinates on the screen.

language:c
void loop()
{
  getAngles(); // Calculate roll and pitch angles based on the acceleromter readings
  oled.clear(PAGE); // Clear the display's internal memory

  // Set dot position
  double bubbleX = LCDWIDTH / 2 - averagedPitch; // Bubble location on x-axis
  double bubbleY = LCDHEIGHT / 2 - averagedRoll; // Bubble location on y-axis

  // Limit bubble position to edge of screen
  if (bubbleX < radiusBubble) { bubbleX = radiusBubble; }
  else if (bubbleX > LCDWIDTH - radiusBubble) { bubbleX = LCDWIDTH - radiusBubble - 1; }
  if (bubbleY < radiusBubble) { bubbleY = radiusBubble; }
  else if (bubbleY > LCDHEIGHT - radiusBubble) { bubbleY = LCDHEIGHT - radiusBubble - 1; }

  // Draw circle relative to dot
  oled.circle(LCDWIDTH / 2, LCDHEIGHT / 2, radiusLarge);
  oled.circle(LCDWIDTH / 2, LCDHEIGHT / 2, radiusSmall);
  oled.circleFill(bubbleX, bubbleY, radiusBubble);

  // Display angle/position once bubble is inside larger target area
  if ( sqrt(averagedPitch * averagedPitch + averagedRoll * averagedRoll) < (radiusLarge - radiusBubble))
  {
    oled.setFontType(0); //Set font to smallest

    oled.setCursor(LCDWIDTH/2 - 21, 0); //x, y
    oled.print("X:");
    oled.print(-averagedPitch);
    oled.setCursor(LCDWIDTH/2 - 21, LCDHEIGHT - 8); //x, y
    oled.print("Y:");
    oled.print(averagedRoll);


//    oled.setCursor(LCDWIDTH/2 - 11, 0); //x, y
//    oled.print(averagedRoll);
//    if (-averagedPitch < 0) { oled.setCursor(LCDWIDTH - 29, LCDHEIGHT/2 - 3); }
//    else { oled.setCursor(LCDWIDTH - 23, LCDHEIGHT/2 - 3); }
//    oled.print(-averagedPitch);
  }

  oled.display();
}
getAngles() Function

This function is executed in the main loop. The code retrieves accelerometer readings, translates the readings into roll and pitch angles, and calculates an average based on a sample set size (avgAmount = 16).

language:c
void getAngles()
{
  averagedRoll = 0.0;
  averagedPitch = 0.0;
  const int avgAmount = 16;

  // Average readings after 'avgAmount' samples
  for (int reading = 0 ; reading < avgAmount ; reading++)
  {
    while (accel.available() == false) delay(1); // Wait for accelerometer connection

    // Retrieve data from accelerometer
    float accelX = accel.getX();
    float accelY = accel.getY();
    float accelZ = accel.getZ();

    // Optional modification: https://www.nxp.com/docs/en/application-note/AN3461.pdf
    //int signZ = constrain(accelZ, -1, 1);
    //double roll = atan2(accelY , signZ * sqrt( accelZ * accelZ + .001 *  abs(accelX) ) ) * 57.3;

    // Calculate roll and pitch angles
    double roll = atan2(accelY , accelZ) * 57.3;
    double pitch = atan2((-accelX) , sqrt(accelY * accelY + accelZ * accelZ)) * 57.3;
    if (constrain(accelZ, -1, 1) == -1) { roll = atan2(accelY, -accelZ) * 57.3; } // Invert if upside down

    averagedRoll += roll;
    averagedPitch += pitch;

    // Debug Print Statements
    //Serial.print(roll, 6);
    //Serial.print(", ");
    //Serial.print(pitch, 6);
    //Serial.print(", ");
    //
    //Serial.print(accelX);
    //Serial.print(", ");
    //Serial.print(accelY);
    //Serial.print(", ");
    //Serial.print(accelZ);
    //Serial.println("");
  }

  averagedRoll /= (float)avgAmount;
  averagedPitch /= (float)avgAmount;

  // Debug Print Statements
  //Serial.print(averagedRoll, 6);
  //Serial.print(", ");
  //Serial.print(averagedPitch, 6);
  //Serial.println(", ");

}

Demo Operation

Below is a demonstration of the example code in action. Enjoy!

demo
Demonstration of the bubble level code operating. (Click to enlarge)

Troubleshooting

Resources and Going Further

Want more information on the SparkFun Qwiic Carrier Board? Check out these links!

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