Youyue 858D+ some reverse engineering + custom firmware

[Barm]

You brought the bare pcb for or which station?

Just PCB for 15 USD. All I've found is only one seller on Ali who sells 858D boards.
I cant rely on a product and model names, because I believe that most of the factories in china just randomly selects a product names, model names, PCB versions, production batches, quality checks, etc. 

[Shock]

Atten and Yihua are actually real manufacturers that make soldering and hot air stations such as the 858Ds. If you can't find the factory or website for a brand it's probably another product rebranded or something generic. There is also apparently a counterfeit problem even with Chinese brands.

http://www.atten.com/
http://yihua-gz.com/

[Barm]

Shock, of course, I know those brands exists.
But it's hard to rely on Aliexpress sellers because selling of a refactored, refurbished and rebranded stuff is a very common, even with a high rated sellers.
Buyers reviews is not a reliable source of information too. In my case - I've received a PCB different from described and reviewed by buyers.
Anyway, I will test this board as soon as I receive my new fan/heater wand. I hope everything will be fine.

So, cooler is marked as 0.2A. How much the main board consumes?
Is 0.3A of 220V/9V/24V transformer enough?

[floobydust]

I just got my YouYue 858D+ station from Aliexpress and did a teardown. The usual tomfoolery.

The wand, base, and box are all labelled "110V" but I found a (cracked) 220V heating element in it. Some math and I get 170W of heat instead of 610W!
A spare heater came free with the unit. 110V 19.8 (610W), 220V 71.6 (675W). I haven't installed it yet, as the heater has heatshrink tubing on the end, not silicone like the present element.

Power transformer is labelled "220V" but is OK on 110VAC.

858D06.PCB 2016.09.29 with MK1840D3 MCU.

I'm drawing a schematic and figured out the hardware, it's pretty basic.

Anyone with 110V version willing to check their heater resistance, see if my numbers are correct.

[floobydust]

Here is the 858D hand wand schematic and pic showing the heating elements 110V/220V.

A 220V heating element works fine on 110V but struggles to get past 350C. Still struggling with Aliexpress vendor to get this looked after.

The safety ground is a real PITA, had to use silver solder and flux on the stainless steel tube.
Nothing else worked. I could not drill a hole to bolt on a crimp connector, it's military grade, lol.

*** UPDATED PINOUT, sorry had male/female flipped 2017-05-08
*** CORRECTED pic posted

[Shock]

Aliexpress sometimes makes Ebay look like a trustworthy marketplace.

[Experimenter]

Hi All,

I just got my Youyue 858D+. At the very first glance, it looks quite Ok for such a cheap device. I plan to go for a custom firmware by Madworm, so the first thing I checked was the MCU type. Surprisingly, it is something marked MK1840 C1Z81706. I'm still studying this thread, but so far I didn't see a mention of this specific chip. I see people here discussing adapters to replace MK1841 with an Atmega. But nothing regarding MK1840. I couldn't find a datasheet for the 1840 either...

I will take a closer look at it in the next days. If there's no working solution for my particular chip, I'll probably look into designing a full new board. I'd be happy to join someone already working on this, too!

[floobydust]

Looking through this thread, I didn't see 858D+ MCU adapter boards for MK1840/41->AVR AtMega168/328.
I was going to lay out an adapter board but I'm kinda lazy and didn't see the fan speed feedback helping much in performance.

YouYue PCB 856D06.PCB '2016.09.29' does not have much room on the right due to the TIP122 heatsink. My MCU is marked MK1840D3 C1Z81708.

Here's my pic of the I/O assignments for the stock MK1840/41 MCU and madworm's 858D+ firmware V1.46; member raihei added a beeper and features calling it his "V1.47" firmware but I'm not sure where it can be found.

[Experimenter]

Looking through this thread, I didn't see 858D+ MCU adapter boards for MK1840/41->AVR AtMega168/328.

I saw several boards shown and discussed.

One of them is the board by GiantGnome:
https://oshpark.com/shared_projects/vLy9R74P

The other one is the board by wguibas (I think this is the latest version):
https://www.eevblog.com/forum/reviews/youyue-858d-some-reverse-engineering-custom-firmware/msg888729/#msg888729

They both are for MK1841D3. I'm not yet sure whether MK1840 is the same.

Here's my pic of the I/O assignments for the stock MK1840/41 MCU and madworm's 858D+ firmware V1.46;

Thanks! I'll try to compare it to whatever my MCU has ...

member raihei added a beeper and features calling it his "V1.47" firmware but I'm not sure where it can be found.

Yep, I saw a mention of that in the recent posts. So far I'm reading the messages from about 1 year ago. I'm sure I'll reach the discussion of rahei's updated firmware soon.

[Experimenter]

I took a closer look at the mainboard. It looks identical to this one that came with a 1841D3. So I tend to think the 1840 and 1841 are basically the same thing...

[bwack]

My unit just came in today from .....







PCB labeled with 2015.08.21
Controller MK1841D3

Actually it is labeled 858D04.PCB also. I have the exact same one (seemingly, but not quite), but its called Atten 858D+. At first glance it looks very much like wguibas' pcb in the kaleep. I believe his was 858D06.PCB.

I have received and soldered up GiantGnomes PCB (smd atmega328p) ordered from OSH Park. Got the MCU programmed. Failed at fan speed. Changed FW to ignore it. Then it failed at temp err ('C err). At all times I had the heater disconnected for safety. The pinout on the adapter is not the same. Example, fan speed (voltage) is measured at ADC5, and ADC5 on the adapter is routed to a .. resistor ?
The display works fine, and so does the FAN_ON signal.

I found the fault. This PCB does not have a reference voltage 2.5V. In the arduino code O added a define for internal reference, and it passes the first software trap (*C err). Lift the handle and holly batman the values rise quickly then drop to 70 or something.. lol

858D04.PCB 2014.06.09  pinout
1 GND
2 DISP3
3 DISP2
4 REEDSWITCH
5 dp
6 HEATER
7 DISP1
8 SW0
9 SW1
10 FAN ON
11 ADC0 (Temp)
12 NC
13 b
14 f
15 a
16 e
17 d
18 c
19 NC ?
20 VCC

Note that there is no ADC reference here.

[bwack]

After extensively checking my 858D04.PCB 2014.06.09 against the adapter (atmega328 smd to MK1841D3) and FW (madworm 1.46), the difference is

My board does not have external 2.5V reference. The FW code uses that. So if I change to internal in Arduino, then I get 1.1V ref. Lol, will try soldering up a 2.5V TL431 circuit.

A schematic would be nice of these adapters

I'm planning to do a video of this modding. I've already done a video about this thread here:

[floobydust]

858D04.PCB is all through-hole and 858D06.PCB is mainly surface-mount.
Comparing their schematics: improved thermocouple filtering, heatsink added to fan speed TIP122 *totally needed!

I too could not find the schematics of the MCU adapters, but realized they are basic. All use resistors or trimpot to make the 2.5V A/D reference- which isn't the greatest because the 7805 drift affects temperature readings.

I'm planning a 858D06.PCB MCU adapter board that clears the heatsink, uses SOT-23 2.5V reference IC, AVR328P TQFP, serial debug pins, lower noise A/D Vcc.
The fan-speed and fan-current circuit I am leaving out because I don't see a payoff. Changing nozzles changes the fan curve and process gain (PID) settings, so I would be ok with a few degrees slop and simpler hardware. Fan fail detect is instead done in firmware, from my tests with the stock MCU.

For the analog scaling, measured my 858D06.PCB (with MK1840D3) readout is 500°C with 2.44VDC at the MCU pin.
It's not 2.5V; they left some headroom for over-temp and open-thermocouple detection.
My trimpot CAL came as gain of 96.6 although I am seeing the circuit ends up with a gain of 89.1 due to crappy filter leading to the A/D. It's not the greatest thermocouple to A/D circuit.

[bwack]

858D04.PCB is all through-hole and 858D06.PCB is mainly surface-mount.
Comparing their schematics: improved thermocouple filtering, heatsink added to fan speed TIP122 *totally needed!

I too could not find the schematics of the MCU adapters, but realized they are basic. All use resistors or trimpot to make the 2.5V A/D reference- which isn't the greatest because the 7805 drift affects temperature readings.

I figured out something regarding the smd atmega328p/mk1841d3 board . The free solder pads are for dividing vdd in two to get 2.5V. I added a TL431 as 2.5V powered through two low pass filter like I've seen in some 858D models. (look up heartoftechnology's schematic).

I'm planning a 858D06.PCB MCU adapter board that clears the heatsink, uses SOT-23 2.5V reference IC, AVR328P TQFP, serial debug pins, lower noise A/D Vcc.
The fan-speed and fan-current circuit I am leaving out because I don't see a payoff. Changing nozzles changes the fan curve and process gain (PID) settings, so I would be ok with a few degrees slop and simpler hardware. Fan fail detect is instead done in firmware, from my tests with the stock MCU.

For the analog scaling, measured my 858D06.PCB (with MK1840D3) readout is 500°C with 2.44VDC at the MCU pin.
It's not 2.5V; they left some headroom for over-temp and open-thermocouple detection.
My trimpot CAL came as gain of 96.6 although I am seeing the circuit ends up with a gain of 89.1 due to crappy filter leading to the A/D. It's not the greatest thermocouple to A/D circuit.

speaking of gain and analog scaling, there is no adjustment for gain in the config of madworm/maugsburger's firmware. wguibas did an attempt to calibrate his station by doing this to the firmware:

temp_inst = (analogRead(A0)/1.9) + temp_offset_corr.value;   // approx. temp in °C

Putting this 1.9 in a config parameter would be great. I'll see what I can do with the fw. I have similar voltages on the ADC0 mcu pin versus temperature.

858D04.PCB schematics, Alex made it : http://poormanelectronics.blogspot.no/2016/08/schematic-and-teardown-of-baku-858d-smd.html

[bwack]

I too could not find the schematics of the MCU adapters, but realized they are basic. All use resistors or trimpot to make the 2.5V A/D reference- which isn't the greatest because the 7805 drift affects temperature readings.

If you start coding, maybe this will help. I sketched this pinout of the adapter showing signals and amega328p's pin names:


Note that DISP3, DISP2 and DISP1 is incorrect. See DIG0,1,2 on the right side. Those are correct. FANON should say FANON_N. etc.

My progress so far. Took two setpoints and measured temp. Calculated offset (39) and gain (0.42) from those points, then put that into the fw. Helped a lot. From earlier in the thread, madworm says that the fw assumes that the adc values are already in Celsius.

[Experimenter]

I would like to build an adapter board with BLDC circuit on it.
I also plan to use TL431 instead of the resistors divider for the 2.5v Aref on ATmega.

There's one thing I don't understand regarding BLDC part. How is this supposed to be setup:



I mean, do we really need these jumpers, or this part can be simplified?

P.S. I'm designing this board in Eagle and will post it here, if anyone is interested.

[esalimster]

Hi , brother do you have the schematics ??
i don t know any circuit component value of this board , i appreciate your help .
i bought your circuit boards in OSH park .

[Experimenter]

If you're looking for schematics of the adapter board, check out this post. There's a .pdf attached, and it was reported later on this schematics is Ok.

I'm making my version based on this one, but I didn't have much time to work on it yet. I hope to have more progress in the next few days...

[floobydust]

The MK1840 (858D06.PCB) and MK1841 (858D04.PCB) are the same as far as MCU adapter PCB's go; same pinout.

Posting a draft schematic of the MCU adapter PCB I am working on, just trying to keep errors to a minimum. Everyone please review and comment and I will keep this thread updated with it.

One MCU adapter board has a PCB layout error with the left & right digits swapped. I definitely have the left digit going to MCU pin2, I am calling this CA1 common anode 1 per the LED datasheet. {bwack seg g is pin 19}.
madworm has serial debug ability in his F/W (but need to disable LED display) so I left PCB pads to connect for that.

TL431's are unstable with certain capacitance, and all need at least a mA, for now C3 is DNP.

[stj]

could you use LM4040 instead of TL431??

[Experimenter]

floobydust, my schematics is about the same. Yours have better comments and proper pin markings!

Did you consider adding BLDC circuit to this board as well?

[bwack]

floobydust, thanks. Regarding numbers and names on atmega328p. Stick to pin-names. Pin numbers changes with package type (TQFP, PDIP etc). Seems ok the draft you have now. You noticed that CA1 and CA3 are swapped. To me it doesn't matter what reference you have or renamed alias you use, as long as i see the port name goes to the pin number on the mk1841d3 Too many variables, and the giantgnome 328p-tqfp adapter works so I stick to that as reference.

[floobydust]

Sensing fan speed - Fan motor current is a terrible waveform. It has a spike that changes amplitude and pulse-width as you vary fan voltage. Running it through the usual low-pass filter/differentiator/comparator etc. and all circuits get mixed up adding spurious pulses at certain fan speeds. See attached scope traces. Note the Tektronix gets it (freq) wrong too 

I'm not convinced knowing fan speed will make this hot air station work better. Why? You still don't know air nozzle size, so the pressure drop and (fan) mass air flow are unknown.

[madworm]

That looks familiar...

Maybe your circuit could be tweaked.

Some images & app note:

https://github.com/madworm/Youyue-858D-plus-FAN-speed-mod/tree/master/Docs

[madworm]

Not pretty & a bit too much variation with fan speed. I agree 😆