An Open Source Cortex-M0 Halogen Reflow Oven Controller With LCD

reflow oven controller

Homemade reflow ovens are a great inexpensive way to quickly solder multiple prototypes at once. [Andy] may just have built one of the best ones we’ve featured so far on Hackaday. For his project a £25 1300W 12litre halogen oven was chosen because of its low cost and fast heating time, the latter being required to follow typical reflow profile ramp-up stages.

To control the AC power [Andy] first bought a chinese Fotek Solid State Relay (SSR) on ebay, which was quickly replaced by an american one after reading concerning reports on the internet. He then made the same ‘mistake’ by buying the typical MAX6675 thermocouple-to-digital converter from the same website, as he spent much time understanding why the measurements were wrong when the IC was just defective. His final build is based around a 640×360 TFT LCD that he previously reverse engineered, the cortex-M0 STM32F051C8T7, a SPI flash, some power regulators and buttons. The firmware was written in C++ and we’ll let our readers visit [Andy]‘s page to see how well  his oven performs.

Comments

  1. Bogdan says:

    just one word…. gorgeous!

    • Sheldon says:

      It’s not just the solution that looks amazing – the write-up is very impressive as well (walks through every aspect of the design with the reasons and issues found: the schematic, the PCB and eve trouble-shooting the build).

      Tempting to repeat his build but make it a dual-purpose controller (I’m hankering after a sous-vide controller)

  2. agjiag says:

    Can you use SSR to drive electric chair?

  3. danieljlouw says:

    Such an incredibly beautiful project with an absolute gorgeous interface… The level of detail on that PCB! Just a pity the oven itself is ugly as death itself. I really hope he builds the guts of the oven over into a more proper metal enclosure that actually resembles a reflow oven!

  4. Waterjet says:

    This guy knows his LCDs!

  5. dext0rb says:

    Great project and nice job on the documentation. Interface is nice and clean. A++++ would read again.

  6. 0xfred says:

    I’m in the middle of a reflow project myself. I will definitely take some inspiration from this. I’m also in the UK but went with a more standard toaster oven as I’d heard those IR ones didn’t give great result. Toaster ovens used to be hard to get here, but there are a few around now. My £18 one from Robert Dyas is 9L and 2kW. It heats up quick enough and I’ve even done a successful manually controlled reflow to test it out.

    I hope my one ends up half as slick as this. Nice work.

  7. dizot says:

    Wow, that’s a great project. Very nicely done!

    I also recently had grand plans to build-up a reflow oven from a toaster oven. My three requirements for the oven were [a] must be a convection oven (promotes more even heat distribution / reduces hot spots); [b] must be digital for easier hacking (heating elements already electronically controlled by relays); must heat to 250­­°C. I found the perfect 1500W digital convection oven used on Craigslist for US$25 – Black and Decker CTO6305…it’s only rated to 450°F (232°C), but the Chipquik SMD291SNL10T5 solder paste I’m using reflows near that temp. That particular oven is great for hacking, since it has three dedicated relays – one for the top 2 heating elements (750W), one for the bottom 2 heating elements (750W), and one for the convection fan. It’s also nice that it displays an approximate temperature on its display, so it’s not completely necessary to throw a thermocouple into the box right off the bat.

    I decided to go ahead and try to run it manually on my latest PCB, which is a ~15 sq. inch (~97 sq. cm) 4-layer design with many very fine pitch (0.5mm) LQFP, QFN, TSSOP, etc. The oven tracked *very* closely to my target profile with no modifications whatsoever. That big 4-layer board reflowed flawlessly, as did other 2-layer boards I’ve thrown into it.

    The point of my story is that if you’re looking for an inexpensive and easy entry to a working reflow oven, that particular model works very well. I may still build a controller, but for the time being, it’s great for one-off or small qty prototypes.

    I’ll be looking to this project for inspiration when I get to that point.

  8. Trui says:

    The cold junction compensation is a bit far from the actual junction.

    • Tyler says:

      Nobody seems to understand thermocouples (or know when not to use them, which is usually, when RTD’s et al are a better solution)…in this case, thermocouples are a fair choice…but yes. That, and T thermocouples are great for a lot of things, and not just K, K, K, K, K…

  9. rasz_pl says:

    This would be even more sexy if Andy reused touchscreen too.

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