Designing a simple and cheap temperature logger. Part 7: Schematics, PCB and source code.

I decided to publish all this project under Creative Commons license (Attribution, Derivatives, Non commercial, ShareAlike). The source code contains a FAT12 filesystem that can be reused to make custom flash drives for other projects.

USB Temperature Logger

(PCB version 1.2, hence the misaligned 3.3V regulator to include a diode. Corrected in the V2.0)

USB Temperature Logger 2

USB Temp Logger Schematics

You’ll find the schematics here: Simple USB temperature logger schematics

The Altium files (including a routed PCB) there: Simple USB temperature logger Altium files

The source code (based on Microchip Applications libraries -Device – Mass Storage – SD Card data logger- MPLABX): Simple USB temperature logger source code

The source code could be improved to increase the robustness of the logger (especially in the case of battery power failure while on logging mode). The PCB allows the monitoring of the battery voltage, it just needs to be implemented in the firmware.

I hope my work will be useful to someone!

Don’t hesitate to contact me (mail in the About section) for questions or comments!

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10 thoughts on “Designing a simple and cheap temperature logger. Part 7: Schematics, PCB and source code.

  1. Hey that’s great! I wanna build my own. Is the V2 safe for building (with a correct diode footprint)? I m gonna send this to my manufacturer. Do you have a BOM and maybe already order numbers for any parts supplier? Would be nice to also put them up here. Thx
    Simon:)

    • Thanks! The schematics and PCB are mature enough for a final prototype. The code needs to be made more rugged for an “everyday use”. As for the BOM, I only have the one extracted from the schematics. My parts were bought at Farnell, but I don’t have a file with all the numbers, sorry.

  2. How about Gerbers? I have no idea what to do with Altium source files. Better yet, put this up on Kickstarter and make a bunch of money.

    • I didn’t include the gerbers, as the design is too small to have the parts designators on the silkscreen. You need to be able to read the Altium files (or make a PCB yourself) to identify the components.
      I thought about kickstarter, but there’s a whole world between a prototype (even mature) like this one and a real commercial product. And I’m not a US citizen anyway, so no kickstarter allowed for me.

  3. Hi, superb build – Are you selling prebuilt temp loggers? I’m not good enough to build these myself.
    Regards,
    Martin

    • Thank you!
      No, I don’t have the time/money to build kits or the final products. And I’d need to sell them for a lot if I only wanted to not loose money (for the time spent)..

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