# A Logger for CircuitPython ## Overview ![](https://cdn-learn.adafruit.com/assets/assets/000/072/834/medium800/micropython_Screenshot_from_2019-03-14_17-58-27.png?1552600721) Have you ever been working on code and needed a view into what was going on as it runs (or tries to)? In many environments you can go into a debugger and poke around. We don't have that ability in CircuitPython, though. If you're like this author, you sprinkle tactical `print` statements as needed. Afterwards you probably go through and remove them or comment them out. Sometimes you miss some. Sometimes you'd like to leave them in place and be able to turn them on and off. There are times when you'd like to see some debugging information, and other times when you want to be notified of critical errors only. A logging framework will let you do all that and more. Specifically, the logging framework described in this guide will: - let you output messages at one of several levels of priority, - ignore messages below a specific priority, - automatically add a timestamp to messages, - provide the string format method support for building messages, - give you convenience methods for the outputting at standard priority levels, - control where messages go, and - make it easy to add new places for messages to go. This guide will go over the use of the framework, walk through the implementation, and work through an example of adding a new destination capability. ## Parts As this service uses RAM and space for longer programs, this guide will note use on M4 and nRF52840-based boards. ### Adafruit PyPortal - CircuitPython Powered Internet Display [Adafruit PyPortal - CircuitPython Powered Internet Display](https://www.adafruit.com/product/4116) **PyPortal** , our easy-to-use IoT device that allows you to create all the things for the “Internet of Things” in minutes. Make custom touch screen interface GUIs, all open-source, and Python-powered using tinyJSON / APIs to get news, stock, weather, cat photos,... In Stock [Buy Now](https://www.adafruit.com/product/4116) [Related Guides to the Product](https://learn.adafruit.com/products/4116/guides) ![Front view of a Adafruit PyPortal - CircuitPython Powered Internet Display with a pyportal logo image on the display. ](https://cdn-shop.adafruit.com/640x480/4116-00.jpeg) ### Adafruit Metro M4 feat. Microchip ATSAMD51 [Adafruit Metro M4 feat. Microchip ATSAMD51](https://www.adafruit.com/product/3382) Are you ready? Really ready? Cause here comes the fastest, most powerful Metro ever. The **Adafruit Metro M4** featuring the **Microchip ATSAMD51**. This Metro is like a bullet train, with its 120MHz Cortex M4 with floating point support. Your code will zig and zag... In Stock [Buy Now](https://www.adafruit.com/product/3382) [Related Guides to the Product](https://learn.adafruit.com/products/3382/guides) ![Angled shot of a Adafruit Metro M4 feat. Microchip ATSAMD51. ](https://cdn-shop.adafruit.com/640x480/3382-13.jpg) ### Adafruit Feather M4 Express - Featuring ATSAMD51 [Adafruit Feather M4 Express - Featuring ATSAMD51](https://www.adafruit.com/product/3857) It's what you've been waiting for, the Feather M4 Express featuring ATSAMD51. This Feather is fast like a swift, smart like an owl, strong like a ox-bird (it's half ox, half bird, OK?) This feather is powered by our new favorite chip, the **ATSAMD51J19** -  with... Out of Stock [Buy Now](https://www.adafruit.com/product/3857) [Related Guides to the Product](https://learn.adafruit.com/products/3857/guides) ![Angled shot of a Adafruit Feather M4 Express. ](https://cdn-shop.adafruit.com/640x480/3857-10.jpg) ### Adafruit Feather nRF52840 Express [Adafruit Feather nRF52840 Express](https://www.adafruit.com/product/4062) The **Adafruit Feather nRF52840 Express** is the new Feather family member with Bluetooth® Low Energy and _native USB support_ featuring the nRF52840!  It's our take on an 'all-in-one' Arduino-compatible + Bluetooth® Low Energy with built-in USB... Out of Stock [Buy Now](https://www.adafruit.com/product/4062) [Related Guides to the Product](https://learn.adafruit.com/products/4062/guides) ![Angled shot of a Adafruit Feather nRF52840 Express. ](https://cdn-shop.adafruit.com/640x480/4062-02.jpg) ### USB cable - USB A to Micro-B [USB cable - USB A to Micro-B](https://www.adafruit.com/product/592) This here is your standard A to micro-B USB cable, for USB 1.1 or 2.0. Perfect for connecting a PC to your Metro, Feather, Raspberry Pi or other dev-board or microcontroller Approximately 3 feet / 1 meter long In Stock [Buy Now](https://www.adafruit.com/product/592) [Related Guides to the Product](https://learn.adafruit.com/products/592/guides) ![USB cable - USB A to Micro-B - 3 foot long](https://cdn-shop.adafruit.com/640x480/592-01.jpg) - [Next Page](https://learn.adafruit.com/a-logger-for-circuitpython/using-a-logger.md) ## Featured Products ### Adafruit PyPortal - CircuitPython Powered Internet Display [Adafruit PyPortal - CircuitPython Powered Internet Display](https://www.adafruit.com/product/4116) **PyPortal** , our easy-to-use IoT device that allows you to create all the things for the “Internet of Things” in minutes. Make custom touch screen interface GUIs, all open-source, and Python-powered using tinyJSON / APIs to get news, stock, weather, cat photos,... In Stock [Buy Now](https://www.adafruit.com/product/4116) [Related Guides to the Product](https://learn.adafruit.com/products/4116/guides) ### USB cable - USB A to Micro-B [USB cable - USB A to Micro-B](https://www.adafruit.com/product/592) This here is your standard A to micro-B USB cable, for USB 1.1 or 2.0. Perfect for connecting a PC to your Metro, Feather, Raspberry Pi or other dev-board or microcontroller Approximately 3 feet / 1 meter long In Stock [Buy Now](https://www.adafruit.com/product/592) [Related Guides to the Product](https://learn.adafruit.com/products/592/guides) ### Adafruit Metro M4 feat. Microchip ATSAMD51 [Adafruit Metro M4 feat. Microchip ATSAMD51](https://www.adafruit.com/product/3382) Are you ready? Really ready? Cause here comes the fastest, most powerful Metro ever. The **Adafruit Metro M4** featuring the **Microchip ATSAMD51**. This Metro is like a bullet train, with its 120MHz Cortex M4 with floating point support. Your code will zig and zag... In Stock [Buy Now](https://www.adafruit.com/product/3382) [Related Guides to the Product](https://learn.adafruit.com/products/3382/guides) ### Adafruit Feather M4 Express - Featuring ATSAMD51 [Adafruit Feather M4 Express - Featuring ATSAMD51](https://www.adafruit.com/product/3857) It's what you've been waiting for, the Feather M4 Express featuring ATSAMD51. This Feather is fast like a swift, smart like an owl, strong like a ox-bird (it's half ox, half bird, OK?) This feather is powered by our new favorite chip, the **ATSAMD51J19** -  with... Out of Stock [Buy Now](https://www.adafruit.com/product/3857) [Related Guides to the Product](https://learn.adafruit.com/products/3857/guides) ### Adafruit ItsyBitsy M4 Express featuring ATSAMD51 [Adafruit ItsyBitsy M4 Express featuring ATSAMD51](https://www.adafruit.com/product/3800) What's smaller than a Feather but larger than a Trinket? It's an **Adafruit ItsyBitsy M4 Express** featuring the **Microchip ATSAMD51**! Small, powerful, with a ultra fast ATSAMD51 Cortex M4 processor running at 120 MHz - this microcontroller board is perfect... In Stock [Buy Now](https://www.adafruit.com/product/3800) [Related Guides to the Product](https://learn.adafruit.com/products/3800/guides) ### Adafruit Feather nRF52840 Express [Adafruit Feather nRF52840 Express](https://www.adafruit.com/product/4062) The **Adafruit Feather nRF52840 Express** is the new Feather family member with Bluetooth® Low Energy and _native USB support_ featuring the nRF52840!  It's our take on an 'all-in-one' Arduino-compatible + Bluetooth® Low Energy with built-in USB... Out of Stock [Buy Now](https://www.adafruit.com/product/4062) [Related Guides to the Product](https://learn.adafruit.com/products/4062/guides) ## Related Guides - [Adafruit Metro M4 Express featuring ATSAMD51](https://learn.adafruit.com/adafruit-metro-m4-express-featuring-atsamd51.md) - [Adafruit Feather M4 Express](https://learn.adafruit.com/adafruit-feather-m4-express-atsamd51.md) - [Introducing the Adafruit nRF52840 Feather](https://learn.adafruit.com/introducing-the-adafruit-nrf52840-feather.md) - [Adafruit PyPortal - IoT for CircuitPython](https://learn.adafruit.com/adafruit-pyportal.md) - [PyPortal Twitter Follows Trophy](https://learn.adafruit.com/pyportal-twitter-follows-trophy.md) - [Edit CircuitPython Code on iOS with Runestone](https://learn.adafruit.com/editing-circuitpython-on-ios-with-runestone.md) - [Larson Scanner Shades (Trinket-Powered NeoPixel LED Strip Glasses)](https://learn.adafruit.com/larson-scanner-shades.md) - [PyPortal 2FA TOTP Authentication Friend](https://learn.adafruit.com/pyportal-2fa-totp-authentication-friend.md) - [Upgrading AirLift ESP32 Firmware](https://learn.adafruit.com/upgrading-esp32-firmware.md) - [Control Electronics with your Brain using NextMind](https://learn.adafruit.com/control-electronics-with-your-brain-using-nextmind.md) - [Bluetooth Restroom Key Proximity Tracker](https://learn.adafruit.com/bluetooth-restroom-key-proximity-tracker.md) - [PyPortal Astronauts in Space](https://learn.adafruit.com/pyportal-astronauts-in-space.md) - [Smart Mirror with PyPortal](https://learn.adafruit.com/smart-mirror-with-pyportal.md) - [Data Logging IoT Weight Scale](https://learn.adafruit.com/data-logging-iot-weight-scale.md) - [RGB LED Matrices with CircuitPython](https://learn.adafruit.com/rgb-led-matrices-matrix-panels-with-circuitpython.md) - [EZ Make Oven](https://learn.adafruit.com/ez-make-oven.md) - [Touch Deck: DIY Customizable TFT Control Pad](https://learn.adafruit.com/touch-deck-diy-tft-customized-control-pad.md) - [MakeCode Arcade with SAMD51 M4](https://learn.adafruit.com/makecode-arcade-with-samd51-m4.md)