Pico RTC DS3231

Precision RTC Module for Raspberry Pi Pico, Onboard DS3231 Chip

Overview

The Pico-RTC-DS3231 is an RTC expansion module specialized for Raspberry Pi Pico. It incorporates high precision RTC chip DS3231 and uses an I2C bus for communication. More external sensors are allowed to be connected thanks to the stackable design.

Features

Standard Raspberry Pi Pico header, supports Raspberry Pi Pico series.
Onboard high precision RTC chip DS3231, with backup battery holder.
- Real-Time Clock Counts Seconds, Minutes, Hours, Date of the Month, Month, Day of the Week, and Year with Leap-Year Compensation Valid Up to 2100.
- Optional format: 24-hour OR 12-hour with an AM/PM indicator.
- 2 x programable alarm clock.
Provide online documentation (Raspberry Pi Pico C/C++ and MicroPython example demos).

Specification

Operating voltage: 3.3V
Backup battery voltage: 2.3V~5.5V
Operating temperature: -40°C ~ 85°C
Power consumption: 100nA (sustains data and clock information)

Pinout

Dimensions

User Guide

Hardware Connection

Setup environment

For an application development environment for Pico on Raspberry Pi, please refer to the Raspberry Pi Chapter.
For the Windows environment setting, you can refer to link.

This tutorial uses the VScode IDE for development in a Windows environment.

Raspberry Pi

1. Log in Raspberry Pi With SSH or press Ctrl+Alt+T at the same time while using the screen to open the terminal.
2. Download and unzip the demo codes to the directory Pico C/C++ SDK. Reference tutorial for users who have not yet installed the SDK.

#Note that the directory of SDK may be different for different users, you need to check the actual directory. Generally, it should be ~/pico/.
wget -P ~/pico https://files.waveshare.com/upload/5/5a/Pico-rtc-ds3231_code.zip
cd ~/pico
unzip Pico-rtc-ds3231_code.zip

c

1. Hold the BOOTSEL button of Pico, and connect the USB interface of Pico to Raspberry Pi then release the button.
2. Compile and run the pico-rtc-ds3231 examples:

cd ~/pico/pico-rtc-ds3231_code/c/build/

#Pico
cmake -DPICO_BOARD=pico -DPICO_PLATFORM=rp2040 ..
#Pico2
cmake -DPICO_BOARD=pico2 -DPICO_PLATFORM=rp2350 ..

make
sudo mount /dev/sda1 /mnt/pico && sudo cp rtc.uf2 /mnt/pico/ && sudo sync && sudo umount /mnt/pico && sleep 2 && sudo minicom -b 115200 -o -D /dev/ttyACM0

3. Open a terminal and use minicom to check the sensor's information.

python

1. Refer to Raspberry Pi's guides to setup Micropython firmware for Pico.
2. Open the Thonny IDE, drag the demo to IDE, and run on Pico as below.

3. Click the "run" icon to run the MicroPython demo codes.

Windows

Download and unzip the demo to your Windows desktop, refer to Raspberry Pi's guides to set up the Windows software environment settings.
Press and hold the BOOTSEL button of Pico, connect the USB of Pico to the PC with a MicroUSB cable. Import c or python program into Pico to make it run.
Use the serial tool to view the virtual serial port of Pico's USB enumeration to check the print information, the DTR needs to be opened, the baud rate is 115200, as shown in the picture below:

Others

The LED light are not used by default, if you need to use it, you can solder a 0R resistor on the R8 position. Click to view the schematic diagram.
The INT pin of DS3231 is not used by default. if you need to use it, you can solder the 0R resistor on the R5,R6,R7 positions. Click to view the schematic diagram.
- Solder the R5 resistor, connect the INT pin to the GP3 pin of Pico, to detect the output status of the DS3231 alarm clock.
- Solder the R6 resistor, connect the INT pin to the 3V3_EN pin of Pico, to turn off the Pico power when the DS3231 alarm clock outputs low level.
- Solder the R7 resistor, connect the INT pin to the RUN pin of the Pico, to reset Pico when DS3231 alarm clock outputs low level.

Resource

Document

Demo codes

Demo codes

Development Software

Pico Getting Started

Firmware Download

MicroPython Firmware Download

C_Blink Firmware Download

Introduction

Raspberry Pi Pico Basics

MicroPython Series

Install Thonny IDE

In order to facilitate the development of Pico/Pico2 boards using MicroPython on a computer, it is recommended to download the Thonny IDE

Download Thonny IDE and follow the steps to install, the installation packages are all Windows versions, please refer to Thonny's official website for other versions
After installation, the language and motherboard environment need to be configured for the first use. Since we are using Pico/Pico2, pay attention to selecting the Raspberry Pi option for the motherboard environment

Configure MicroPython environment and choose Pico/Pico2 port
- Connect Pico/Pico2 to your computer first, and in the lower right corner of Thonny left-click on the configuration environment option --> select Configture interpreter
- In the pop-up window, select MicroPython (Raspberry Pi Pico), and choose the corresponding port

Flash Firmware

Click OK to return to the Thonny main interface, download the corresponding firmware library and burn it to the device, and then click the Stop button to display the current environment in the Shell window
Note: Flashing the Pico2 firmware provided by Micropython may cause the device to be unrecognized, please use the firmware below or in the package
- Pico firmware library
- Pico2 firmware library
How to download the firmware library for Pico/Pico2 in windows: After holding down the BOOT button and connecting to the computer, release the BOOT button, a removable disk will appear on the computer, copy the firmware library into it
How to download the firmware library for RP2040/RP2350 in windows: After connecting to the computer, press the BOOT key and the RESET key at the same time, release the RESET key first and then release the BOOT key, a removable disk will appear on the computer, copy the firmware library into it (you can also use the Pico/Pico2 method)

MicroPython Series

【MicroPython】 machine.Pin class function details
【MicroPython】machine.PWM class function details
【MicroPython】machine.ADC class function details
【MicroPython】machine.UART class function details
【MicroPython】machine.I2C class function details
【MicroPython】machine.SPI class function details
【MicroPython】rp2.StateMachine class function details

C/C++ Series

For C/C++, it is recommended to use Pico VS Code for development. This is a Microsoft Visual Studio Code extension designed to make it easier for you to create, develop, and debug projects for the Raspberry Pi Pico series development boards. No matter if you are a beginner or an experienced professional, this tool can assist you in developing Pico with confidence and ease. Here's how to install and use the extension.

Official website tutorial: https://www.raspberrypi.com/news/pico-vscode-extension/
This tutorial is suitable for Raspberry Pi Pico, Pico2 and the RP2040 and RP2350 series development boards developed by Waveshare
The development environment defaults to Windows. For other environments, please refer to the official tutorial for installation

Install VSCode

First, click to download pico-vscode package, unzip and open the package, double-click to install VSCode

Note: If vscode is installed, check if the version is v1.87.0 or later

Install Extension

Click Extensions and select Install from VSIX
Select the package with the vsix suffix and click Install
Then vscode will automatically install raspberry-pi-pico and its dependency extensions, you can click Refresh to check the installation progress
The text in the right lower corner shows that the installation is complete. Close VSCode

Configure Extension

Open directory C:\Users\username and copy the entire .pico-sdk to that directory
The Copy is completed

Open vscode and configure the paths for the Raspberry Pi Pico extensions

The configuration is as follows:

Cmake Path:
${HOME}/.pico-sdk/cmake/v3.28.6/bin/cmake.exe

Git Path:
${HOME}/.pico-sdk/git/cmd/git.exe    

Ninja Path:
${HOME}/.pico-sdk/ninja/v1.12.1/ninja.exe

Python3 Path:
${HOME}/.pico-sdk/python/3.12.1/python.exe

New Project

The configuration is complete, create a new project, enter the project name, select the path, and click Create to create the project
To test the official example, you can click on the Example next to the project name to select
The project is created successfully
Select the SDK version
Select Yes for advanced configuration
Choose the cross-compilation chain, 13.2.Rel1 is applicable for ARM cores, RISCV.13.3 is applicable for RISCV cores. You can select either based on your requirements
Select default for CMake version (the path configured earlier)
Select default for Ninjaversion
Select the development board
Click Complie to compile
The uf2 format file is successfully compiled

Import Project

The Cmake file of the imported project cannot have Chinese (including comments), otherwise the import may fail
To import your own project, you need to add a line of code to the Cmake file to switch between pico and pico2 normally, otherwise even if pico2 is selected, the compiled firmware will still be suitable for pico
set(PICO_BOARD pico CACHE STRING "Board type")

Update Extension

The extension version in the offline package is 0.15.2, and you can also choose to update to the latest version after the installation is complete

Arduino IDE Series

Install Arduino IDE

First, go to Arduino official website to download the installation package of the Arduino IDE.
Here, you can select Just Download.
Once the download is complete, click Install.

Notice: During the installation process, it will prompt you to install the driver, just click Install
600px

Arduino IDE Interface

After the first installation, when you open the Arduino IDE, it will be in English. You can switch to other languages in File --> Preferences, or continue using the English interface.
In the Language field, select the language you want to switch to, and click OK.

Install Arduino-Pico Core in the Arduino IDE

Open the Arduino IDE, click on the file in the top left corner, and select Preferences

Add the following link to the attached board manager URL, and then click OK

https://github.com/earlephilhower/arduino-pico/releases/download/4.0.2/package_rp2040_index.json

Note: If you already have an ESP32 board URL, you can use a comma to separate the URLs as follows:

https://dl.espressif.com/dl/package_esp32_index.json,https://github.com/earlephilhower/arduino-pico/releases/download/4.0.2/package_rp2040_index.json

Click Tools > Development Board > Board Manager > Search pico, as my computer has already been installed, it shows that it is installed

Upload Demo at the First Time

Press and hold the BOOTSET button on the Pico board, connect the pico to the USB port of the computer via the Micro USB cable, and release the button after the computer recognizes a removable hard disk (RPI-RP2).
Download the program and open D1-LED.ino under the arduino\PWM\D1-LED path
Click Tools --> Port, remember the existing COM, do not click this COM (the COM displayed is different on different computers, remember the COM on your own computer)
Connect the driver board to the computer using a USB cable. Then, go to Tools > Port. For the first connection, select uf2 Board. After uploading, when you connect again, an additional COM port will appear
Click Tools > Development Board > Raspberry Pi Pico > Raspberry Pi Pico or Raspberry Pi Pico 2
After setting it up, click the right arrow to upload the program

If issues arise during this period, and if you need to reinstall or update the Arduino IDE version, it is necessary to uninstall the Arduino IDE completely. After uninstalling the software, you need to manually delete all contents within the C:\Users\[name]\AppData\Local\Arduino15 folder (you need to show hidden files to see this folder). Then, proceed with a fresh installation.

Open Source Demos

MircoPython video demo (github)
MicroPython firmware/Blink demos (C)
Raspberry Pi official C/C++ demo (github)
Raspberry Pi official micropython demo (github)
Arduino official C/C++ demo (github)

Support

Technical Support

If you need technical support or have any feedback/review, please click the Submit Now button to submit a ticket, Our support team will check and reply to you within 1 to 2 working days. Please be patient as we make every effort to help you to resolve the issue.
Working Time: 9 AM - 6 PM GMT+8 (Monday to Friday)

Submit Now