Another Mini Hotplate but with 56x56 mm Area

[Montvydas]

Has anyone tried taking apart one of those cheap PD 65W mini hot plates from Aliexpress and see if it uses stm32. There is a youtube video here of a similar one if Aliexpress link doesn't work. It would be cool to see IronOS running on it, since you can buy it for as low as £10 and I really like the bigger surface area of 56x56 mm as opposed to the 30x30 on MHP30 😄

[Ralim]

If anyone tears one down and looks whats inside I would be curious. Definitely possible to add if hardware supports it :)

[StevenSeifried]

Sounds interesting. I could not resist and bought one for 19 Euros, should have arrived by the end of this month (12 day delivery to Germany).

When it arrives, I will tear it down. @Ralim do you want the pictures of the PCB here in this discussion or in a separate issue?

[Ralim]

Here is good, I've ordered one too but slow shipping (2-8 weeks) so you should beat mine handily.

[janowakps]

@Ralim any updates?

[Ralim]

It was discussed somewhere else, but basically the chipset in these cant run IronOS so it wont be ported for them.

[Montvydas]

I ordered one as well, it was hella cheap and it even includes the PD charger (I hope it won't break on first try!) for £16 with taxes included 😄 I will likely tear the hot plate apart just to ensure it's electrically safe to use, it seems to have this "easy to disassemble" vibe to it.

[StevenSeifried]

Mine arrived today. PCB is equipped on one side

• STC 8H3K64S2
• NCE6050KA
• HDM CH224K

[paulfertser]

8051 architecture, 64 KiB flash, 3 KiB SRAM. Does this really leave a chance?

[paulfertser]

Apparently it can be flashed directly over USB though.

[paulfertser]

No, this one isn't USB-capable, so UART only. Shouldn't be a complicated process if one writes a replacement firmware. But reading out the original firmware isn't possible (at least no method known to the general public is available).

[ia]

Hello. Sorry for the late reply and bothering with off-topic but I'm just curious... could you tell me, please: did you make these photos with photo camera & macro-lens or was it one of those digital microscopes? And in case if it was the latter, could you type the full name of the brand/model? (I was just thinking about getting one of those for myself) Thanks.

[StevenSeifried]

I used my smartphone (Samsung Galaxy A52s 5G) to take the photos

[paulfertser]

So be it. Let's hope it's not too bad even without IronOS. Please post your review after you get some experience with it here.

[StevenSeifried]

I'm unable to get more than 215-220 °C out of it (according to the current temperature shown on display). The temperature was set to 250 °C. Tested with three different 65W USB-PD chargers and two different USB-C-to-USB-C cables (100W and 240W)

[Montvydas]

That is strange, since I managed to reach 247C after setting it for 250C (when it's ~5C to the set value it stops heating up and just maintains the temperature while very slowly approaching the set value) using Macbook 100W brick + original cable in just about 2min 30 sec. In addition, the hot plate managed to reach 200C in 1 min 10sec and 220C in just about 1 min 40 sec, which is pretty decent. I guess you wouldn't use it for standard non-leaded solder paste, but it would work great for low-temp non-leaded or leaded pastes.

Edit: Could it be that you need more than 65W to reach above 220C maybe?

[paulfertser]

Using a 20 V 3.25 A 65 W PD source I got to 220 degrees in 2.5 minutes, 230 in 3 minutes, 240 in 4.5 minutes. Around 245 was its maximum.

[Rixxxi]

I orderd one of these today. Looking forward to my first ever reflow soldering with this little thing.

The device doesn't have and need (imo) many features. Maybe they can be adopted to IronOS. Current features are:
* Left button -> temperature down
* Right button -> temperature up
* Both buttons -> Start/Stop heating

Have you noticed there is a menu including PID settings?
The menu options are explained in this video: https://youtu.be/3ig7yCUP1xg

I'm unable to get more than 215-220 °C out of it (according to the current temperature shown on display). The temperature was set to 250 °C. Tested with three different 65W USB-PD chargers and two different USB-C-to-USB-C cables (100W and 240W)

Maybe changing the PID settings could make it reach the max temperature?

[Blaster1920]

Just got one myself.
Looks like the stable pid values for me are:
KP 112
KI 004
KD 160
This thing desperately needs and autotuning sequence.

[Rixxxi]

Awesome! Thanks for posting your values!

I was using the hot plate yesterday and this morning I wondered how to tune the PID values. I have no idea.
What process you used to figure out which values work stable?

[Blaster1920]

Didn't use any particular process, but: Ki wasn't doing much do I disabled it. I figured out it wasn't looking enough far ahead in time so I increased Kd. Tried to get Kp and Kd well balanced to avoid oscillations. Now the marginal offset error was too high, -2degrees, activated Ki and played a bit with it. This is all after trying Nicholson's, and failing in doing so. With a proper autotune you might get even closer to perfection. I performed all the testing with a 1.6mm fr4 board unpopulated but with solder on top, with setpoint at 170° since I'll be using this plate mostly for flexible pcbs. Suggestion: for very thin/flexible/super small PCBs, you might want to tune down Kd slightly, say by 5 or 10.

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On Sat, 9 Sept 2023, 18:27 Rixxxi, ***@***.***> wrote: Awesome! Thanks for posting your values! I was using the hot plate yesterday and this morning I wondered how to tune the PID values. I have no idea. What process you used to figure out which values work stable? — Reply to this email directly, view it on GitHub <#1698 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACWD5UC3STJRGNHGL55B63DXZSRGRANCNFSM6AAAAAAY7BDAUE> . You are receiving this because you commented.Message ID: ***@***.***>

[krunchiekrunch]

Just found out this hot plate is entirely open sourced, including the code and hardware
https://oshwlab.com/oshwhub.com/pd-protocol-high-definition-mini