FNIRSI HS-02A/B Soldering Iron

[Juan-P-84]

As suggested, I am creating a new discussion for this iron and its possible support to use IronOS.

As stated in the other thread: @Ralim

I just got a reply from the supplier, and unfortunately it is the same as with others who tried "The information is the Engineer's secret"
Pity, awesome hardware, but using a locked Firmware...

Someone on Reddit has taken the HS-02A apart:

https://www.reddit.com/r/soldering/comments/1d4no48/jbc_style_usb_soldering_iron_roundup_teardown/

https://youtu.be/hosUIRGxT-Y

I will ask there if he might be able to assist.

[joric]

So the CPU in HS-02 is apparently Nation N32L403, so it DOES NOT have Bluetooth, as opposed to CH571F used in HS-01 (#1614).

Sadly no DOOM on this iron, despite 3 buttons and color screen, MCU is just 24K RAM/128K ROM, DOOM needs 256K RAM and 256K data for MiniWAD. TS1C wireless iron from Miniware also uses a subpar processor (CH579), both the iron and the stand (32K RAM/250K ROM).

[Juan-P-84]

From the Thread over on Reddit:

Model | USB-PD | CPU | Mosfet
FNIRSI | WCH CH224K |Nation N32L403 | AOSMD 4407A

Here are the parts for these components, with datasheets linked:

Here are the parts for these components, with datasheets linked:

Model USB-PD CPU Mosfet
FNIRSI WCH CH224K Nation N32L403 AOSMD 4407A

[Juan-P-84]

The FNIRSI Store I bought it from got back to me, saying they will have a word with their Tech team regarding Technical information & Schematics, after I emphasized how important IronOS is, and that the other manufacturers like MiniWare and Pinecil benefit a great deal from it.

[tranquoc2002]

Hi, I currently have an HS-02 A, but it's broken. The reason is that the N32L403 cpu died due to a burnt MOSFET, which sent 20V directly into the cpu. I ordered a new cpu on Aliexpress, but I'm not sure if it can be flashed with the firmware normally, or if I need to flash it in a different way ??

[kwangoettems]

Hi man! did u fixed the iron? I was soldering a lion battery and my HS-02B just made a pop sound and died, I think its the same problem as yours, thanks !

[Sisqoboy2]

Anyone had any luck fixing it? I also have a shorted AOSMD 4407A MOSFET and the issue is asking for tip and once it has it it heats up without stopping. Just wondering how and what to check to make sure the CPU isn't dead.

[Aldekein]

The IPS display replacement part I've got:

But the disassembly process looks so hard.

[kwangoettems]

Heey. Do u have a link for the screen? I was disassembling mine and I broke the ribbon

[WolfXP92]

Good day, could you please help me with troubleshooting? I'm not very good with circuit design, but I can handle a soldering iron. The issue is that I had a short circuit in the insert, I was soldering the + from which I powered the soldering iron, and now when I connect it to the power supply, it constantly shows 'insert tip' on the display. Visually, the resistor R010 was damaged, I replaced it, as well as the diode T4 near the buzzer. The soldering iron enters the settings and even updates the firmware, but it didn't help

[ruevs]

https://github.com/danielhoang123/HS-02_Official_Firmware
But it does not look like it actually has the source - just a bunch of libraries :-(

[bugparty]

this one is not realated to this Soldering Iron

[JohnTheCoolingFan]

Has anyone managed to even flash an official firmware update? My HS-02A does get recognized as a storage device, but copying the firmware file to it doesn't start the flashing process, there's no reaction and the soldering iron still prompts me to copy the file.
I'd imagine if IronOS support was made for this firmware then it'd be kinda important to be able to flash it.

[Juan-P-84]

I had issues initially, but found if you drag and drop the file onto the 'storage' the iron shows up as, after it copies over the iron restarts loading the updated firmware.
Did this for the latest two updates, worked each time.

[JohnTheCoolingFan]

I had issues initially, but found if you drag and drop the file onto the 'storage' the iron shows up as, after it copies over the iron restarts loading the updated firmware. Did this for the latest two updates, worked each time.

Thank you, this worked for me. Drag-and-dropping the file into the "storage" list where the iron shows up as mounted, and then doing it again and choosing replace.

[Ivy5000]

I have recently acquired an HS-02B and I'd really quite like to run ironOS on it. I have it taken apart and I have basic electrical tools, if someone could tell me what's needed / point me to a resource that does, I'll try to get that information here!

[Ivy5000]

Seems like they've started removing info from the MCU package

[JohnTheCoolingFan]

Does it not respond to button presses? Unclear from your message whether you tried that or not.

[lflondonol92]

It doesn't respond at all to the OK button presses. However, I just tried to press both arrows at the same time and it takes me to the setup page, so the unit itself isn't frozen. I think the OK button is faulty

[Ralim]

I have picked up one of these in the recent Aliexpress sales since then it was remotely reasonably priced 😓.
They have locked down the firmware on the original unit, so no cheating and using the debug interface to poke the pins to figure out their state.

The firmware files have a fairly simple leader on them, I have managed to flash a blank file as well as byte mode their firmware (no signing / encryption / checksums).

The firmware updater works on Linux for me, with the same double-copy trick as all Miniware devices.

Next required steps for basic support:

1. Port over the drivers for this chip and add them to the build system
2. Write a driver for the LCD screen
3. Figure out the pinout of what pin on the MCU goes where
4. Write the HAL implementation to map the hardware to tie into IronOS

I'm not promising any resutls here, but I have kicked the tires and its possible.

[Sanekkk12]

I took some better pictures of the device's board. If this helps with firmware development, I can also try to draw its schematic.

[n30f0x]

My new iron got version 2 fw, i'll try to contact support to get .bin file, officially posted one is still 1.8.

[n30f0x]

it's for future findings

[Sisqoboy2]

it's for future findings

You should have thanked me rather than writing an irrelevant reply.
Anyway, this is for A not B so good luck finding one for the B.

[BayteTheProtogen]

APP_HS_02A_V2.1.0_251111.bmp
Here's the file downloaded (because it expires in 13h), just change the extension from .bmp to .bin after downloading it didn't let me upload otherwise.
checksums match, SHA256: dda5b6b602843dbaf4ccee10f913143d77ed6439dfa0ba5a3f16569ceef1d5ea APP_HS_02A_V2.1.0_251111.bin

[Firebie]

File for HS-02B
APP_HS_02B_V2.0.1_251111.zip

[balbulator]

APP_HS_02A_V2.1.0_251111.bmp Here's the file downloaded (because it expires in 13h), just change the extension from .bmp to .bin after downloading it didn't let me upload otherwise. checksums match, SHA256: dda5b6b602843dbaf4ccee10f913143d77ed6439dfa0ba5a3f16569ceef1d5ea APP_HS_02A_V2.1.0_251111.bin

What's new in this firmware (compared to 1.8)

[GreyXor]

FYI I asked FNIRSI for 2.1.0 changelog. They told me :
We have made optimizations to the temperature stability and display.
They gave me this link : https://www.mediafire.com/file/r0tohbq9ntbmr6e/APP_HS_02A_V2.1.0_251111.bin/file

[Sisqoboy2]

Thanks for that.

[limitedeternity]

Is there 2.1.0 for HS-02B?

[PanKleszcz]

EDIT: with a great help of @GreyXor we have finally a working version of a tool that allows for backing up flash memory of HS-02:
hs02_msdmem_0.0.7.zip

Original post:

Anybody willing to help? I need to fix bootloader in my HS02...
For that I've prepared a simple MSD firmware that allows for flash download over USB:
hs02_msdmem_hs02.zip

FW should show "HS-02 USB MSD v0.0.1" on the screen and 2MB flash drive should appear in the system.

Cons:

1. I was not able to test if above file is actually accepted and works with the official bootloader
2. While unlikely, flashing my FW may brick your HS02
3. Bacause of (2.) it'd be nice if the procedure was performed by somebody that already disassembled their device and is able to attach a debugger if stuff goes sideways

Pros:

1. I got enough experience with N32L403 that porting IronOS should be doable now
2. Eventually the above FW will turn into an opensource MSD bootloader for ARM targets

After that it should be of course possible to flash back the original FW.

So if anyone is brave enough, I'd appreciate if they upload generated FLASH.BIN and SYSOPT.BIN :)

[GreyXor]

I will try again later with another USB port. one file after, meticulously and saving the dmesg export each time, maybe that can give us ideas

• FYI this one is a HS02A and I got it 3 months ago.
• FYI² my computer is a framework 13 laptop AMD Ryzen AI 9 HX 370 and I run arch linux on linux 6.19-rc8. I have no issues with any of my USB devices, I mean, I have confidence in my USB ports. I'm still going to try another USB controller 👍

[PanKleszcz]

@GreyXor I think I got it. When the bootloader switches to user app it globally disables interrupts...
v0.0.6 should have it fixed hs02_msdmem_0.0.6.zip

[GreyXor]

Will test tomorrow. I don't have the iron with me atm. Thanks for your effort!

[GreyXor]

@PanKleszcz it worked!
ramflash.zip

[PanKleszcz]

Wonderful news. I'll edit the first post and add the new version here (I've also finally tamed USB clock recovery HW with the help of AN_N32G43x_N32L43x_N32L40x_Xtal_Less_Application_Note so if anyone want to backup their device we finally have a stable solution.

[Juan-P-84]

Been a while since I checked in on threads I'm following.
Great to see all the awesome progress that's been made! 🙌🏻
As soon as I've got access to a pc I'll give this a shot, sounds really promising.

[roryjoe]

Just received my HS-02A today, what a time to be alive with a new IronOS just released!

Not sure if it's helpful now, but I've uploaded the extracted files using the utility above on the stock firmware. The Flash.bin, Ram.bin and Sysopt.bin.

It looks like mine came with 2.1.1, and I got it from FNIRSI website direct, which is interesting if it required optimisation back in March as oer GreyXor's post above.

Flash+Ram+Sysopt HS02A 2.1.1.zip

[bugparty]

If someone is willing to order a Soldering Temperature Tester for example https://a.co/d/07FrnqB2 and do the following measurements for maybe back and forth at most 4 times I am happy to add support for version B(you can return the tester kit after the measurements) You need to cold down to under 100 degrees each time before your measurements, set target temperature for 200, 250, 300, 350 degrees, measure the actual temperature reading and tip uv( my specific firmware version will shows that)

…

On Tue, Jul 28, 2026 at 4:43 PM roryjoe ***@***.***> wrote: Just received my HS-02A today, what a time to be alive with a new IronOS just released! Not sure if it's helpful now, but I've uploaded the extracted files using the utilitiy above on the stock firmware. The Flash.bin, Ram.bin and Sysopt.bin. It looks like mine came with 2.1.1, and I got it from FNIRSI website direct, which is interesting if it required optimisation back in March as oer GreyXor's post above. Flash+Ram+Sysopt HS02A 2.1.1.zip <https://github.com/user-attachments/files/30483116/Flash%2BRam%2BSysopt.HS02A.2.1.1.zip> — Reply to this email directly, view it on GitHub <#1935?email_source=notifications&email_token=AALQ26GIRZ2VPS3RZX6K3XL5HE3A5A5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNZYGE4TCNBWUZZGKYLTN5XKOY3PNVWWK3TUUVSXMZLOOSWGM33PORSXEX3DNRUWG2Y#discussioncomment-17819146>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AALQ26GC7R6C4FURWYWQKAL5HE3A5AVCNFSNUABGKJSXA33TNF2G64TZHM3DQMBYGI3TGMB3IRUXGY3VONZWS33OHM3DQMZXHAYTFILWAI> . You are receiving this because you commented.Message ID: ***@***.***>

[rsipka]

Hi, I have both HS-02B and a thermometer. Which firmware should I load on the B version to do the test?

I noticed on B version the original firmware undershoots the temp as well (as A, but by not so much) but it's not linear. I think it also depends on the tip as the resistance variation seems to be higher in those Chinese ones.

For now, I tried your firmware on the HS-02A and it overshoots the temp linearly (so far as I can tell) by about 33 degrees C, whereas original undershoots by 40-50C.

If someone is willing to order a Soldering Temperature Tester for example https://a.co/d/07FrnqB2 and do the following measurements for maybe back and forth at most 4 times I am happy to add support for version B(you can return the tester kit after the measurements) You need to cold down to under 100 degrees each time before your measurements, set target temperature for 200, 250, 300, 350 degrees, measure the actual temperature reading and tip uv( my specific firmware version will shows that)

[bugparty]

Let me check

…

On Wed, Jul 29, 2026 at 3:47 PM Humayung ***@***.***> wrote: Hey thank you very much! I really needed the wattage info. Waiting for the B version tho. But i will just try this. I don't recommend to flash the B version because the temperature parameters need to be adjusted Thanks for the info! Tried it, cant get it to be installed to begin with. It doesn't respond when i dragged the bin file on it multiple time (i'm on linux) — Reply to this email directly, view it on GitHub <#1935?email_source=notifications&email_token=AALQ26HU4PGY7BXOF7WKMLD5HJ5GPA5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNZYGMZDQOJQUZZGKYLTN5XKOY3PNVWWK3TUUVSXMZLOOSWGM33PORSXEX3DNRUWG2Y#discussioncomment-17832890>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AALQ26HIV5KAH27SGS5UCO35HJ5GPAVCNFSNUABGKJSXA33TNF2G64TZHM3DQMBYGI3TGMB3IRUXGY3VONZWS33OHM3DQMZXHAYTFILWAI> . You are receiving this because you commented.Message ID: ***@***.***>

[Js517621]

I accidentally erased my N32L403 Flash via ST-Link. Could anyone kindly share a full 128KB Flash Dump (0x08000000) for HS-02B?

[Humayung]

here,

#1935 (reply in thread)

[bugparty]

I’m sorry I was busy moving my home to a new location, I will release B version this week or next. By the way I am pretty satisfied with the results of my version A firmware, way more aggressive compared to the factory settings, the only thing I concerns is the factory’s max temp 450degree only actually of 400degree , I calibrate to 450 with an error of 5-10degree.also factory firmware seems want to slow down the initial cool heat up process for some reason I don’t know

…

On Tue, Aug 11, 2026 at 10:46 AM Humayung ***@***.***> wrote: any update bro? @bugparty <https://github.com/bugparty> — Reply to this email directly, view it on GitHub <#1935?email_source=notifications&email_token=AALQ26BNAL45SU2YXLMOIQT5JNLW7A5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNZZG44TGOJRUZZGKYLTN5XKO3LFNZ2GS33OUVSXMZLOOSWGM33PORSXEX3DNRUWG2Y#discussioncomment-17979391>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AALQ26H3DELLTYGW5N5OJ7T5JNLW7AVCNFSNUABGKJSXA33TNF2G64TZHM3DQMBYGI3TGMB3IRUXGY3VONZWS33OHM3DQMZXHAYTFILWAI> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[Humayung]

Wow your findings really significant, very curious how things will turned out. No pressure bro, thanks for working on this awesome project!

[igorjganaga95]

This is amazing, my friend! Thank you to everyone who participated in the development and testing. This is a great firmware for my soldering iron.

[igorjganaga95]

I kindly ask the developer or testers to create a detailed video guide on YouTube covering all menu items and settings, and also provide the same information in text format. I would be extremely grateful.

[Ralim]

Every setting has a description here

Which ones are you missing?

[igorjganaga95]

I looked at the text guide; it was very useful. Thank you. I have one more question: will you have the opportunity or the desire to add Russian to the firmware in the future? It would be very convenient, and I would be immensely grateful.

[bugparty]

Okay, let me try comrade

…

On Sat, Aug 15, 2026 at 4:24 PM igorjganaga95 ***@***.***> wrote: I looked at the text guide; it was very useful. Thank you. I have one more question: will you have the opportunity or the desire to add Russian to the firmware in the future? It would be very convenient, and I would be immensely grateful. — Reply to this email directly, view it on GitHub <#1935?email_source=notifications&email_token=AALQ26FOSPA3K72OE6EG2SD5KDWMRA5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCOBQGM2TGOJWUZZGKYLTN5XKO3LFNZ2GS33OUVSXMZLOOSWGM33PORSXEX3DNRUWG2Y#discussioncomment-18035396>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AALQ26CK6FAI3IM72S53IN35KDWMRAVCNFSNUABGKJSXA33TNF2G64TZHM3DQMBYGI3TGMB3IRUXGY3VONZWS33OHM3DQMZXHAYTFILWAI> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[Gubbfittan]

First off! Thank you for the firmware, it is awesome. I don't know if you have done something to the tip connection issue, but I have not had a single one since I updated the firmware.
Second. Is it hard for a rookie to translate the language? To do my little contribution I could do a translation to swedish if that is not already done?

[TheCorruptedEngineer]

Where is the HS02-B firmware?

[tranminh821]

Your IronOS firmware is excellent. Thank you so much for creating such a great alternative firmware.

The thermal compensation when soldering large joints is really good — the temperature barely drops, which is extremely important when making a solder joint. Meanwhile, my original firmware version 2.1.1 cannot compensate for the heat loss quickly enough when soldering large joints. It is honestly quite bad.

What’s even worse is that they seem to intentionally keep the temperature displayed on the screen unchanged even though the actual temperature of the soldering tip is dropping. The power bar also seems misleading, since it only increases to around 30% when I touch the soldering tip to a large piece of copper.

Once again, thank you very much for your great work! I'm really looking forward to your future updates, if there are any.

[tranminh821]

Should I recalibrate the CJC every time I switch to a different tip?

[skeet70]

I haven't tried bugparty's firmware, but In case this helps anyone else on the internet that got here trying to figure out how to flash their HS-02A with only a Mac available, here's the generated script that worked for me. It has instructions at the top of the script.
fnirsi_hs02_flash.py