Youyue 858D+ some reverse engineering + custom firmware

[madworm]

I'm writing a custom firmware for this device. More to come pretty soon. More info on my blog.

What works so far:

    display
    reading the 2 buttons
    reading the wand sensor (reed contact)
    fan ON / OFF override
    crude heater control – just ON / OFF

Todo:

    read the thermo-couple voltage from the OP-7
    implement a control loop for the temperature (most likely PID) + sensible calibration
    read the fan status signal (not quite sure what it is)


For now, here's a part of the schematic and a short video.

[KingsTwisted]

A bit of a quinky-dink....   

Check out the ** SCHEMATIC ** and  ** PROGRAM **
posted at https://www.eevblog.com/forum/reviews/yihuastandigyum-cha-937d-soldering-station-got-one/

I just got through reverse engineering a YiHUA 937D Temperature controlled soldering iron.
It's a bit simpler then your 858D+, but you might find some of the work useful.

NOTE: Schematic done with KiCad (Open Source "Schematic and PCB designer" Dave reviewed some time ago)
NOTE: If you want the KiCad files, let me know.

[george graves]

What's your goals in this?

Someone did a video, and apperently the display is totally faked, and that the air temp totally overshoots at start up.  Is that what you are trying to fix?

Also, think you can do it all with a firmware only solution - if so - that would be niceeeeeeeeeeeeeeeeeeeeeee!

[madworm]

The first goal is to get it to display the actual temperature and not just the set-point. The set-point is a nice-to know, but I really do like to know the real thing.

I've accomplished that. It is usable as of now.

The temperature overshoot issue is my 2nd goal. As of now I have implemented a PD control loop, which works reasonably well, but the parameters need more tweeking. Initial power-up is still a bit iffy with respect to overshoot, but once the device is warmed up, moving the temperature around isn't too bad. Work in progress :-)



I'll tweak the way the device controls the heater a bit more and may finally go to full PID control. Currently the very low temperatures ( < 130°C ) take too long to reach, as the minimum duty cycle for the heater is still too long, so the tiniest bit of heating action will almost overcompensate any intended temperature drop.

I hope there is a firmware-only fix for this device.

[madworm]

I think I'm done :-)

The massive overshoots are a thing of the past.

I've also managed to lower the minimum temperature to about 65°C and added the option to let it blow cold air.

[jinzo]

Looks quite interesting. I'm eyeing this hot air station for quite some time, looks like I'll have to get one finally.
For anyone interested in the code itself, it's hosted in madworms git: http://git.spitzenpfeil.org/cgi-bin/gitweb.cgi?p=Youyue-858D-plus.git;a=summary

Thank you for your work and effort.

[madworm]

Just in case my server should be offline, all the stuff is also on github.

[amyk]

After the improvements, maybe you should call it the 858D++

[madworm]

Maybe :-)

Some more stuff:

* persistent set-point storage (I somehow forgot about that)
* better button handling ( +-1 or +-10 depending on press-time)
* displays error message if wand is not connected or temperature out of range
* show °C set-point when temperature is within +- 4°C (don't show insignificant fluctuations on display)

[madworm]

Firmware now supports full PD / PID control. Vital parameters can be changed by the user (via buttons / display) and are stored in eeprom. The default values can be restored in case something goes wrong.

Tuning PID parameters is a good exercise for one's patience...

[Monkeh]

I'll have to see if I can adapt this to my Atten unit.

E: If the Youyue is meant to be the clone, it's significantly better built than the Atten.. No isolation slots, no attention to clearance, single-sided PCB with all the dodgy reverse soldering that implies, two 14-pin sockets used for the 28-pin micro, flux everywhere, damaged ground lead from poor stripping..

And of course a completely different (Holtek) micro.

[amyk]

I'll have to see if I can adapt this to my Atten unit.

E: If the Youyue is meant to be the clone, it's significantly better built than the Atten.. No isolation slots, no attention to clearance, single-sided PCB with all the dodgy reverse soldering that implies, two 14-pin sockets used for the 28-pin micro, flux everywhere, damaged ground lead from poor stripping..

And of course a completely different (Holtek) micro.

According to some other posters here, there's also fake Attens. Youyue (Google suggests "youtube" on searching for it ) sounds like a clone of Aoyue. How long until we see a Yatten?

[Monkeh]

I'll have to see if I can adapt this to my Atten unit.

E: If the Youyue is meant to be the clone, it's significantly better built than the Atten.. No isolation slots, no attention to clearance, single-sided PCB with all the dodgy reverse soldering that implies, two 14-pin sockets used for the 28-pin micro, flux everywhere, damaged ground lead from poor stripping..

And of course a completely different (Holtek) micro.

According to some other posters here, there's also fake Attens. Youyue (Google suggests "youtube" on searching for it ) sounds like a clone of Aoyue. How long until we see a Yatten?

Atyue?

[madworm]

I'll have to see if I can adapt this to my Atten unit.

I think the basic principle of operation is pretty much the same. Even if the Atten units have a different micro. You may get away with designing a small adapter PCB and do a brain-swap with a suitable AVR. Or try getting a compiler for the holtek chip.

BTW, here's that latest (and probably final) video. I'm playing with the PID settings a bit.

As usual, my camera-work is terrible. I know.

[Monkeh]

I'll have to see if I can adapt this to my Atten unit.

I think the basic principle of operation is pretty much the same. Even if the Atten units have a different micro. You may get away with designing a small adapter PCB and do a brain-swap with a suitable AVR. Or try getting a compiler for the holtek chip.

It appears to be an identical circuit, yes. I'll probably just splice together an adapter as I have a few 328PUs kicking around the place.

[madworm]

Judging by the number of Atten units out there... you might be able to sell a couple of those adapter boards. Don't forget a programming header. You don't want to know how many times I had to pull those chips out before I added the code to change parameters via the buttons.

If you have the boards made at the usual suspects, you will naturally end up with a couple of spares...

[Monkeh]

I shall ponder it after I lace one together the old fashioned way

On the other hand, I might just make a whole new main board, because what's there is.. far from pretty.

Feast your eyes:


I'm sure you recognise that part of the circuit.

[madworm]

Yes, the colour looks familiar

And someone forgot to whittle away parts of the PCB in critical locations.

Well, whatever you do, be safe and make a post about it.

[Monkeh]

Yes, the colour looks familiar

And someone forgot to whittle away parts of the PCB in critical locations.

Well, whatever you do, be safe and make a post about it.

That didn't work so well.

[madworm]

Sooo, the TRIAC went with a bang?

Surely something must have (been) shorted out. Was the micro pulled out when it happened?

[Monkeh]

Sooo, the TRIAC went with a bang?

Surely something must have (been) shorted out. Was the micro pulled out when it happened?

I made a stupid at 4am. I pulled the power TRIAC, forgot the driver. Did not stop the heater coming on. Just added a second one. Gotta go clean that up and replace some resistors..

You did ask me to post whatever I did.. 

[Monkeh]

Well, now that I've tested the pinout, blown the shit out of my TRIAC driver, and renewed my hatred for working with AVRs.. I'll get cracking on a real adapter board for this thing. And order a new driver..

[madworm]

Got my simple adapter boards in the mail. Finally a device with an ISP connector. I still have a grudge against the person who did the board layout for omitting it.

It works fine, but it was a trivial thing anyway :-)

Whether the clearance distances to the HV parts are still sufficient is subject do discussion.

[Orpheus]

Atyue?

Gesundheit

[Monkeh]

Atyue?

Gesundheit

Do you know how long I've waited for that?