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RTC Pi

Real time clock for the Raspberry Pi and Single-Board Computers

The Raspberry Pi is a great low-cost computer with thousands of different uses, but one thing it does not come with is a real-time clock. This means that every time you switch off your Raspberry Pi, it forgets what the time is, and you have to manually set it again the next time you switch your Raspberry Pi on.

The RTC Pi is a battery backed real-time clock for the Raspberry Pi and other compatible single board computers. It keeps track of the time while the Raspberry Pi is switched off and allows it to retrieve the current date and time from the RTC Pi when it is switched back on.

A real-time clock is beneficial for stand-alone projects where your Raspberry Pi will not have a network connection and, therefore, no way to retrieve the current date and time from the internet.

The RTC Pi is powered through the host Raspberry Pi using the GPIO port, and extended pins on the GPIO connector allow you to stack the RTC Pi along with other development boards. The RTC Pi uses the DS1307 RTC real-time clock and a CR2032 battery to maintain the date and time when the main system power is unavailable.

Mounting holes are provided so you can securely bolt the RTC Pi to your Raspberry Pi with our mounting kit (sold separately).

The RTC Pi also includes an I2C logic level converter allowing you to connect other 5V I2C devices to your Raspberry Pi.

The RTC Pi can also be used on Arduino boards and the Raspberry Pi Pico when connected via the I2C bus.

The i2c address for the DS1307 RTC is 0x68. If you use this board alongside the ADC Pi or ADC Differential Pi boards, you will need to change the i2C address on those boards.

Warning: Do not connect the RTC Pi to your Raspberry Pi when the power is connected without a CR2032 battery installed. This can cause damage to the DS1307 RTC chip.

The RTC Pi Plus uses a CR2032 button battery (battery not included).

Technical Details

Input Ratings & Specifications

Spec Ratings
Supply Voltage 4.5V to 5.5V
Logic Voltage at GPIO Port 3.3V
Logic Voltage at I2C Header 5V

3D CAD Model

Click to downloadRTC Pi - 3D CAD File (STEP Format)

Schematic

Click to View
View the schematic PDF.

Mechanical Drawings

Click the image to enlarge

Compatibility

The RTC Pi communicates over the industry-standard I²C protocol, which is supported by the vast majority of modern SBCs. If your board exposes SDA and SCL on a 40-pin GPIO header running at 3.3 V logic, the RTC Pi should work.

Platform Status Notes
Raspberry Pi A+ / B+ Tested Primary platform, full library support
Raspberry Pi 2 / 3 / 4 / 5 Model B Tested All variants confirmed, including 400 & 500
Raspberry Pi Zero / Zero W / Zero 2 W Tested All variants confirmed
Raspberry Pi Pico Tested Via I²C pins; use MicroPython library
Orange Pi Tested Enable I²C via board config; see our Orange Pi guide
Asus Tinker Board Tested Enable SMBus/I²C; see our Tinker Board guide
Odroid Tested I²C device node must be enabled in OS config
Other 40-pin I²C SBCs Likely compatible Any board with 3.3 V I²C on SDA/SCL and a GND + 3.3 V or 5 V supply pin should work
Using an unlisted SBC? As long as your board provides a 3.3 V I²C bus, a 3.3 V supply, and a ground connection, the RTC Pi will communicate correctly. Enable I²C in your OS (e.g., via armbian-config, orangepi-config, or your board's device-tree overlay), then use our Python or C library. Visit our Other Supported Platforms knowledge base page for configuration guides and community tips.

Using the RTC Pi Standalone or with Non-Standard Headers

The RTC Pi does not have to plug directly into an SBC's header. You can connect it to any microcontroller or SBC, including those with a non-40-pin layout, by wiring just four signals from the host to the RTC Pi header:

3.3 V Pin 1
SDA Pin 3
SCL Pin 5
GND Pin 6

If you are not connecting an external 5 V supply, also connect the 5 V (Pin 2) from your host. This makes RTC Pi compatible with Arduino-class boards and any SBC that exposes I²C on individual breakout pins rather than a 40-pin header, including the Raspberry Pi Pico.

Assembly Instructions

The RTC Pi is supplied with a 40-pin GPIO connector, and the battery holder is unsoldered.

We supply the RTC Pi this way because the Raspberry Pi is also provided without a GPIO header, and the RTC Pi could therefore be fitted both above or below the Raspberry Pi.

Before using the RTC Pi, you need to solder the 40-pin GPIO connectors onto the PCB and the battery holder.  

We suggest soldering the 40-pin GPIO connector first and then the battery holder. Soldering the battery holder first will make it difficult to access the pins on the GPIO connector. The PCB has an outline for the battery connector to ensure the correct fitting.

PCB Header Assembly Jig

Download and print our PCB Header Assembly Jig to hold your circuit board when soldering the header pins.

Use

Datasheets

Code Libraries and Tutorials

All AB Electronics software libraries are open-source and available on our GitHub repository. Libraries are available for the following languages and frameworks, covering Raspberry Pi, Orange Pi, Asus Tinker Board, Odroid, and other Linux-based SBCs with I²C support:

Language   Notes
Download Python 2 and 3 code samples Python Works on any Linux SBC with the smbus or smbus2 package
Download MicroPython code samples MicroPython For Raspberry Pi Pico and other MicroPython-capable microcontrollers
Node js code samples Node.js Suitable for server-side or IoT automation on Linux SBCs
C code samples C Bare-metal performance on any I²C-capable Linux board
C++ code samples C++ Bare-metal performance with object-orientation on any I²C-capable Linux board
Download Windows 10 IOT code samples Windows 10 IOT Windows 10 IOT Library & Demos

See the RTC Pi Knowledge Base for platform-specific setup guides, including I²C configuration walkthroughs for Orange Pi, Asus Tinker Board, and Odroid.

RTC Pi Articles & Tutorials

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Important Information

This development board/kit is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, OR EVALUATION PURPOSES ONLY and is not considered by abelectronics.co.uk to be a finished end-product fit for general consumer use. As such, the goods being provided are not intended to be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including product safety and environmental measures typically found in end products that incorporate such semiconductor components or circuit boards. Persons handling the product(s) must have electronics training and observe good engineering practice standards. This development board/kit does not fall within the scope of the European Union directives regarding electromagnetic compatibility, restricted substances (RoHS), recycling (WEEE), FCC, CE or UL, and therefore may not meet the technical requirements of these directives or other related directives. Note: documents in Portable Document Format (PDF) require Adobe Acrobat Reader 5.0 or higher to view, download Adobe Acrobat Reader or other PDF reading software for your computer or mobile device.

Shipping and Delivery

For orders under £35 and tracked orders, the following delivery charges apply.

Shipping Rates

United Kingdom

Service Cost  Estimated Delivery Time 
Royal Mail 1st Class £3.29 1 - 3 days (Mon - Sat)
Royal Mail Special Delivery (Tracked) £8.49 Next day (Mon - Sat)

European Union

Deliveries to: Austria, Belgium, Bulgaria, Croatia, Republic of Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain and Sweden. 

Service Cost  Estimated Delivery Time 
Royal Mail Airmail Service £4.29 3-5 Working Days **
Royal Mail International Tracked and Signed £12.99 3-5 Working Days **

Rest of the World

Service Cost  Estimated Delivery Time 
Royal Mail Airmail Service £5.99 5-7 Working Days **
Royal Mail International Tracked and Signed £18.99 5-7 Working Days **

* Free delivery uses the Royal Mail 1st Class service for UK orders and Royal Mail Airmail Service for international orders.

** All International destinations are subject to customs clearance at the destination country, which can add a short delay to your delivery times. Additional import duty may be charged for your order by customs on arrival to your country based on the order value.

We have a full list of all available delivery destinations on the Shipping Country List.

We aim to dispatch your order within 1 working day.  

Working days are normal weekdays; dispatch times do not include Saturdays, Sundays and national holidays. Delivery transit times do not include national holidays and Sundays but may include Saturdays, depending on the delivery service provider in the destination country.

You can view details of international shipping issues and delays with the Royal Mail airmail service at Royal Mail International Incident Bulletin.

You can check the status of your order by going to the My Account area of the website.

Import One-Stop Shop (IOSS) FAQ

What is the Import One-Stop Shop (IOSS)?

The Import One-Stop Shop (IOSS) is a system introduced by the European Union to simplify VAT collection for goods valued at €150 or less that are shipped to customers in the EU from outside the EU. By using IOSS, sellers collect VAT at the point of sale, ensuring that buyers do not have to pay additional import taxes or customs fees upon delivery.

How does IOSS benefit me as a customer?

IOSS makes your shopping experience easier and more transparent by:

Including VAT in the purchase price you see at checkout.

Eliminating unexpected customs charges or fees upon delivery.

Reducing potential delivery delays caused by customs clearance.

Will I have to pay any additional charges when my order is delivered?

No. If your order is covered by IOSS, all applicable VAT and import charges are already included in the price you pay at checkout. There will be no additional charges when your order is delivered.

How do I know if my order is covered by IOSS?

All orders shipped to EU countries and valued at €150 or less are covered by our IOSS registration. If your order qualifies, the VAT and import fees will be automatically calculated and included in the total price during checkout.

Does IOSS apply to all products?

IOSS applies to goods valued at €150 or less that are shipped from outside the EU to customers in EU member states. Certain items, such as excisable goods (e.g., alcohol or tobacco), may not qualify for IOSS coverage.

What happens if my order exceeds €150?

For orders valued above €150, IOSS does not apply. In such cases, import VAT and any applicable customs duties will need to be paid separately, usually upon delivery. We recommend checking your local regulations for further details.

Do I need to do anything to use IOSS?

No action is required on your part. We handle all the necessary IOSS processes on our end to ensure your order is VAT-compliant and free from additional import fees.

Does IOSS reduce delivery times?

Yes, IOSS can help speed up delivery times by streamlining the customs clearance process. Since VAT is prepaid, your order is less likely to be delayed during customs inspections.

Is IOSS available in all EU countries?

Yes, IOSS applies to all EU member states. Regardless of where you are in the EU, you can enjoy the benefits of IOSS when shopping with us.

Can I claim VAT back if I am VAT registered in the EU?

If you are VAT registered in the EU and wish to claim VAT back, please use the Guest Checkout and enter your VAT registration details before placing your order. It is not possible to enter your VAT details when using the PayPal express checkout.

What should I do if I still have questions?

If you have any further questions about IOSS or your order, feel free to contact our customer support team. We’re here to help!

Delivery Duty Unpaid for orders sent outside of the United Kingdom and EU over 150 euros

All orders sent to countries other than the United Kingdom and EU over 150 euros are shipped on a DDU (Delivery Duty Unpaid) basis, and the recipient may be subject to local taxes and customs import duty, which is charged on the value of the order.

Payment of these fees is the sole responsibility of the customer. 

Order Tracking

Our standard shipping service is not tracked, and we cannot supply tracking information for your order.

We can offer alternative shipping using Royal Mail, tracked and signed for service. You can select this option at checkout. Please note full end-to-end tracking depends on the tracking service from the regional postal service in the destination country.

Once your order has been sent, you can view your tracking code, which is available in the My Account section. Please allow up to 72 hours for your tracking code to be added to your order after despatch.

Returns, refunds and your right to withdraw

Two things apply to your order: your statutory rights as a consumer, and our 180-day returns guarantee on top of them. We never use the guarantee to reduce your legal rights — where the law gives you more, the law applies.

Your right to withdraw (consumers)

If you bought from us as a consumer, you have 14 days to change your mind for any reason, without needing to keep the item sealed.

The 14 days run from the day you, or someone you nominate, received the goods. Where an order arrives in separate deliveries, the period runs from the day you received the last item.

To withdraw, use our withdrawal function, labelled "Withdraw from contract here", in the My Account area under your order. If you checked out as a guest, use the link in your order confirmation email and verify your order number and email address. You can also tell us in any other clear statement, such as an email. Either way, we'll send you a timestamped acknowledgement by email.

You may open and inspect a board to check it works, as you would in a shop, and still withdraw. You don't have to keep it unopened to exercise this right. You may be liable for any reduction in the item's value caused by handling beyond what's needed to establish how it works.

Once you withdraw, we refund the price you paid plus the standard outbound delivery cost, within 14 days. We may hold the refund until we've received the goods back, or until you show proof you've sent them. You're responsible for the cost of returning the items, and the parcel is your responsibility until it reaches us, so we recommend a tracked or insured service.

Some items are excluded from the statutory right to withdraw, for example goods made or configured to your specification. We'll make this clear before you order where it applies.

Faulty items

Separately from the right to withdraw, if a board is faulty or not as described, your statutory rights apply. Consumers in the EU have a legal guarantee of two years from delivery. All Raspberry Pi add-on boards are tested during production, and all inputs and outputs are checked to ensure they are within the specified ratings. We cannot accept returns for faults caused by over-voltage applied to the inputs by the purchaser, as this is damage rather than a fault.

Our 180-day returns guarantee

In addition to your statutory rights, if for any reason you are unhappy with your purchase you may return it within 180 days of the date you received it, in its original condition and unopened, with any seals and shrink-wrap intact, and we will issue a full refund for the price you paid. This guarantee is our own, beyond what the law requires, which is why it asks for items to be unopened. Opened items can only be accepted under this guarantee if they are faulty.

When returning an item, please state why you are returning it and whether you want a refund or an exchange.

Business customers

The right to withdraw applies to consumers. Orders placed in the course of a business, including boards bought as components for incorporation into other products, are not covered by the consumer right to withdraw. Our 180-day guarantee still applies as set out above.

Refunds

The time a refund takes to reach you depends on the banks involved, but it would normally take 3 to 5 working days to complete once issued.

Your statutory rights

Nothing in this policy affects or limits your statutory rights. Where our terms are more generous than the law requires, the more generous terms apply; where the law gives you more, the law applies. Customers in the United Kingdom have an equivalent 14-day cancellation right under the Consumer Contracts Regulations 2013.

Removed Delivery Destinations

We regret that we had to remove the following countries from our delivery destinations due to a very high failure rate of our parcels being delivered using the Royal Mail airmail service. This resulted in us refunding all of the missing orders, and we cannot continue to make such large losses by sending parcels to destinations where a large percentage of the items are lost in the postal systems.

Brazil, China, Israel, Mexico, Saudi Arabia, Singapore, Sri Lanka, Taiwan, Turkey and the United Arab Emirates.

Also, due to problems with the courier delivering parcels to these destinations, we cannot use a third-party courier service for these delivery destinations due to the extra costs involved.

Customers can purchase our products from one of our international resellers