Replies: 26 comments 88 replies
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That sounds very much like a power issue. Quickly checked their schematic, they are using MicroOne ME6211 LDO with 500mA peak current, the ESP32-C3 specified [email protected] peak power when RF TX is working. In theory, it should be good enough. The NodeMCU ESP32-C3-32S-Kit uses a AMS1117-3.3 1A LDO, Espressif's ESP32-C3-DevKitM-1 uses the SGM2212-3.3XKC3G/TR, a 800mA LDO. I wonder if bypassing the LDO and supplying 3.3V directly makes it work reliable. |
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For the record, it does not seem to help to supply 3.3v directly or even additionally, see my replies to TD-er |
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Give it a try ;-) Whatever reason it is, the board is not useable as it is sold. |
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Is it failing at the moment you are writing to flash? This might require significantly more power. |
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Update: I have three of these.
Considering all this I think it's safe to say this device is not recommended for development purposes. |
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Ugh, that really doesn't sound promising.
Is that also true when connecting 3V3 supply directly? |
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Hmm the need to reduce TX power on WiFi suggests an antenna impedance mismatch, or a resonance frequency mismatch. Does it make a difference if you put your thumb on the antenna? If so, then it is for sure an antenna mismatch. |
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Touching the antenna parts makes no difference. No temperature differences from a "functional" device. It might even be the cause of the issue as those parts are normally hidden by a shield but here they are unshielded and might have been broken by ESD. |
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Or just bad soldering which adds enough resistance to cause voltage drops when drawing current. |
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Bad soldering affecting all devices? I knew about 10 of this modules, and none is working. |
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I've just done this and touching the antenna does make some difference, in that I get a couple of steps further along the wifi setup before the crash. I have previously been able to get this same unit to work somewhat by reducing TX power but my current program is Rust + ESP_IDF based and I have yet to figure out how to reduce TX. Lolin C3 mini V2.1 has a different design and antenna, and seems to work without a problem. |
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There is a fix found by @hallard . Thx!
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Take care it's a dirty fix interesting to test distance performance. Wemos state another fix (cleaner or not) is to change wifi Tx power as follow, WiFi.setTxPower(WIFI_POWER_8_5dBm); |
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Change the TX power to 8.5dBm does work really bad. Not a solution. |
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Nice you tried, avoid me doing this stupid test. But to be honest not sure my fix will do better, for sure result will not be as good as a good matching circuit. But following solution should give better results, just remove resistor and soldering 3.1cm wire len on the pad (or 6.2cm or 12.4cm)
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I've checked the design guidelines and wemos schematic. Looks like the full schematic is inductor plus two capacitors from both sides. But wemos put only one capacitor and replaces inductor with 0 ohm resistor. Looking on Reference PCB design it's clear that external antenna connector goes after the CLC circuit. Could result be better if we populate all the circuit with recommended elements? |
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As I suspected this fix is not really the solution, this afternoon I played with fixed board for a customer, and I never had success to get ESPNow working and send data, so I give a try with unmodified board with soft fix as follow // Set device as a Wi-Fi Station
WiFi.mode(WIFI_STA);
WiFi.setTxPower(WIFI_POWER_8_5dBm);It worked immediately, so depending on your usage hard fix or soft fix is up to you, but my 2 cents, stay away from these board and use a well known one https://www.adafruit.com/product/5405 (not sure it was tested but I'm sure it's working) |
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Hi, I have the same problems as reported here: In the URL [https://www.wemos.cc/en/latest/c3/c3_mini.html] Wemos shows the Schematic V1.0.0: C15 (1pF) y C16 (NC) Capacitor
I am unable to measure this capacitors and inductor. The Espressif pdf says: I am unable to debug through the serial port but this is only my problem Best Regards. |
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I see there is a v2.1.0 version now that doesn't mention this 7.5 dBm wifi power issue. Ordered a bunch of them and will let you know if it works out of the box. |
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They replaced the PCB antenna by a ceramic one |
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The sold all borked boards the had. Never made a notice nor the did an exchange program. |
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If it is correctly matched of course 😂 |
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It does appear than some capacitor adjustment was done with the new revision. And they added a Neopixel as basis for saying "new and enhanced" without mentioning problems with the first iteration. |
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It is possible to design a cheap working C3 board. Buy this https://wiki.luatos.com/chips/esp32c3/board.html (contracted version) instead of Lolin and supporting an evil company who is fooling his buyers. It is available from different sellers on Ali under 3€. |
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yes |
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@fluppie where did you buy v2.1.0 ? On https://lolin.aliexpress.com/ there's still v1.0.0 listed (at least now). Still angry that i bought some of the 1.0.0 rev, i guess that's a risk for such ultra low cost boards. The rgb led is fancy tho. |
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Probably sold out, then ... |
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waiting for mine that should arrive, hoping it's new revision, surprise in the mailbox soon... |
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Arrived today, conform, with external antenna, not tested yet
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Have you had time to test it and see if it works? |
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I have this board v2.1 and I still have occasional issues with Wifi. The issue was especially present when the board is mounted on a breadboard, when it's "flapping around in the breeze" with an USB cable the Wifi mostly succeeds. The txpower setting improves the situation but I would not call it reliable. |
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I had a couple myself, they don't seem to have a very good range, do they? From my work desk they have a bit of an hard time connecting while other boards (like the S2 or other brands) had less problems. Anyone noticed something similar? |
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If your Wemos C3 Mini is the older V1.0.0, the bad Wifi is a well-known issue, the reason for even having this thread. |
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no sorry i forgot to specify they are the new 2.1.0 version with ceramic antenna |
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Do you have a other C3 board, which you can compare? |
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Can anyone confirm v2.1.0 C3 works ok? I want to replace some tasmota esp8266 with an esp32 and it would help enormously if I can use the same footprint as the current d1 mini so I can keep the already builtin pcb's. |
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In my experience, Tasmota is as stable on ESP32-S2 (as in Wemos S2 Mini) as other variants. Only thing is that there may be antenna trouble with non-Wemos branded clones of that board. I've heard nothing bad about the new revision of the C3 Mini board, but for me the old one does actually not work too badly with the workaround of |
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I have the original Wemos boards. But the C3 v1.0.0 has the antenna issue. Just curious if this is fixed on the V2.1.0 (before I buy a bunch of them ;) |
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Well, IME the Wemos C3 Mini V2.1.0 connects with |
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Ok thanks, just to confirm that this (fix/workaround) is still needed on the v2.1.0 boards as well? |
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Hello , I have Lolin c3 v1.0.0 and I have tried tasmota so many times but i could not get that to work . the board worked when flashed with wled using below commands. esptool.exe -p COM10 erase_flash I have only one to test and I am yet to try the same process with tasmota but if you need to test the files I used the look here https://discord.com/channels/473448917040758787/779395228624617512/1104464327068622959 |
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My Tasmota experience with that board is that the workaround of |
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@dosipod Just dump the Lolin C3 rev 1.0 in the bin. There are other cheap working C3 boards. |
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I agree with you and we have only one of each new chip c3 , s2 and s3 to test with students and they all rev 1,0. I would not go again and buy but I cant just throw money in the bin . We have plenty of normal esp32 /8266 and we test new chips for learning as it is a challenge to make something like this work and we were about to do the HW mod listed in this post . If that is working with wled might be at least you could try to compile in tasmota and provide the bins ( including bootloader and partitions ) so others might be able to fix existing boards with tasmota . We are thinking that tasmota bin could also be good but the flashing process is the issue as it seem with wled |
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I don't understand your point
If you have identified a software fix for that specific board, you are free to fork the source code, apply the change and compile your own build. That would surely be a very good exercise for students. We will never add into Tasmota any code that is specific to a given board. Our build are generic per processor type and should work as-is with any board with that CPU. |
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Just an idea if you need to flash lots of units with the same issues... |
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I am not sure about other suggestions but best thing is for the person suggesting something is to test it by himself which we did already with wled . As the title of the post is "Lolin Wemos C3 mini needs hardware mod to work " I think it is a bit confusing if the software fix is enough or not but it seems so with wled you do not need a HW mod |
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Having some workaround (like lowering WifiPower) to get better results is not the same as having a fix of the problem. "Working or not" is not a binary black/white, but many shades of grey. Of course, if someone knows details of what WLED is doing differently...... |
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I have no idea what WLed does and also not what Tasmota does. So maybe WLed does something similar? |
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I've seen indications of clones of the Wemos S2 Mini having pretty bad antenna design. I'm having no trouble with the original Wemos-branded one. |
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I received the v2.1 board and I can confirm that the antenna does not work reliable even on the newer version of the board. @TD-er you wrote this: can you show us that feature? is it public? may we use it in our projects? |
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Sure, it rougly comes down to this: The basic idea is that the RSSI is in the same order of magnitude on both ends (AP receives your data with similar strength as you receive the AP) The datasheet parameters are defined here: More in-depth documentation on this: https://espeasy.readthedocs.io/en/latest/Tools/Tools.html#wifi-tx-power Whenever you use it, I would appreciate it if you mention in your code where you got it from. |
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many thanks for the kind answer @TD-er. I appreciate it. The ESP return an RSSI of -30 when it's on the air and perfectly connected to the network, when on the metal breadboard the ESP can't connect to wifi, if I remove it from the breadboard it connects pretty instantly. with this RSSI it's not possible to calculate the correct signal strength, I think that this board is bad designed and nothing can be done... |
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Please also read the link to the documentation I added at the end of my post. Especially when you're placing the ESP's antenna close to metal, you may end up with a lot of reflections of the WiFi signal. First some very basic antenna theory... N.B. not only the length of the antenna has an effect on the SWR, but also the materials surrounding the antenna. Simply hold the antenna in your hand, or place it in an enclosure and the SWR may change. Such reflections can have numerous effects on the WiFI performance. The ESP processors do have some ways to automatically tune the antenna within some parameters. I personally would try to start with a lower maximum TX power in such setups. Right now, I have no idea how to 'detect' in software whether the ESP experiences a lot of RF reflections. |
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Implemented in dev branch v12.5.0.3 Use command |
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Yay! |
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I'm not a Tasmota user but I still hope this is useful, I ordered 5 of the LOLIN C3 Mini V2.1.0 modules and none of them connect to WiFi reliably or at all 99% of the time. I purchased these from the LOLIN Official Store. They are all missing a component near the C3 aerial. I've circled the missing component, all 5 boards are like this.
I'll probably try a refund but it's been pretty deflating to end up with 5 useless boards. So I'd at least like to warn people to probably avoid LOLIN they don't seem very reliable. |
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I'm using the Lolin C3 Mini V2.1.0 board (which it looks like your board is, see the other side) without "surprising" Wifi trouble (works ok, but maybe not the best), and the circled position is also unpopulated on my boards. To me, that layout detail looks like a place to create a solder bridge if having some reason to cut the trace to the ceramic antenna, as leaving the antenna pin unconnected can lead to chip damage. Note that having such dev boards on a breadboard will significantly increase the risk of the radio antenna not working as well. It can help mounting it at the end, with less metal near to the antenna. The original V1.0.0 revision was known to not work well on WIfi, but usually became workable with Tasmota setting |
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The unpopulated place is for a optional? cap. Looking at an earlier screenshot of the board in this discussion there is a cap placed. It seems Lolin does not manage to deliver always working boards. |
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Not to dismiss your findings, but keep in mind that antenna tuning is an iterative process (for the manufacturer) Typically you have a pi-network of capacitors and/or coils to match the impedance of the antenna. On a perfectly tuned antenna (chip antenna is typically quite well tuned) you only need a 0 Ohm resistor in series with the RF trace. On the other hand, I've also seen multiple boards in the past (not these C3 mini boards) where wrong parts were used on these antenna matching parts. A good test to see if it is related to a badly matched antenna is to try with reduced TX power. |
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I've tested the 3 of the boards in a breadboard 2 are still lacking header pins and I've tested them with no breadboard and they all have the same problem.
Reducing the tx power to 8.5 has helped and been the only way these boards have reliably connected to WiFi, but they remain mostly non working. The LOLIN D1 mini V4.0.0 I have from the same company have zero problems with their WiFi and work every time. I'm testing with my phone tethered now and I have 2 WaveShare ESP32-C6-Pico's coming to compare with, I'll keep posting to this thread if the project does not mind. |
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Follow up: I use MicroPython so excuse the Python. Test code: import machine, network, time
status = {
1000: "idle",
1001: "connecting",
202: "wrong password",
201: "no AP found",
203: "connect fail",
1010: "got IP"
}
wlan = network.WLAN()
wlan.active(True)
if not wlan.isconnected():
wlan.connect("Galaxy A22 5G", "REMOVED")
while not wlan.isconnected():
print(f'Status: {wlan.status()}, {status[wlan.status()]} ', end='')
for i in ["channel", "hostname", "txpower", "pm" ]:
print(f'{i}: {wlan.config(i)} ', end='')
print()
time.sleep(1)
pass
for i in ["channel", "hostname", "txpower", "pm" ]:
try:
print(f'{i}: {wlan.config(i)} ', end='')
except:
pass
print(f'rssi: {wlan.status("rssi")}')This is testing with my phone (which you can see from the code) the boards are right next to it. Board removed from the breadboard: Board in the breadboard (never connects): Board in the breadboard and I touch near the C3 aerial with my finger: Again this is for the Lolin C3 Mini V2.1.0 which is supposed to fix the issue from the pervious revision, it obviously does not. Conclusion the aerial system is just, terrible? Testing photo:
Edit: LOLIN D1 mini V4.0.0 connects so fast it doesn't even enter the the isconnected loop: Probably because it has an aerial that isn't the size of a pea:
Edit: Updated the code to work on the LOLIN D1 mini V4.0.0 without throwing an exception. |
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The picture of the board on a breadboard does exactly show how NOT to use those boards on a breadboard. A little bit about antenna theory... The chip antenna used on your badly performing board does use a different substrate, which does impose a much smaller factor, which allows to make smaller antennas. Also the trace inside those chip antennas is likely some coil. Major advantages of such chip antennas:
Disadvantages of such chip antennas:
As a general rule of thumb, larger antennas can pick up more energy and thus have better sensitivity. Now the tuning, as the resonance frequency is only 1 parameter of an antenna. Other parameters are:
Impedance matching is the hardest part to do right, as there are lots of parameters affecting antenna performance. Ground plane Reflections Impedance matching My guess is the manufacturer did not do this on these boards, so the antenna tuning parts are wrong. Also the ground plane which typically surrounds the chip antenna on at least 2 sides is missing. The chip antenna manufacturer usually has very strict instructions on how the ground plane should be present around those chip antennas. |
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Here's the end of the older V1.0.0 design, which works for me with lowered TX power (as in automatic TX power selection instead of fixed), even with the antenna in the middle of a breadboard, with "extra" wires between breadboard and antenna circuit. While the design very much looks like the PCB antenna was replace with a small ceramic antenna at the end, the layout around the antenna circuit was moved, and not same capacitor positions populated. |
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Just took another look at the picture posted by @sfromis It looks like it is just a PCB with traces formed into a 'coil' by using vias. That isn't a 'chip antenna', but rather a piece of PCB There are 7 vertical stripes of 1.15 mm, 6 or 8 diagonal stripes of 1.43 mm and 14 vias of 1.0 mm. Wavelength of 2.4 GHz = 124.9 mm So it looks like this isn't a proper matching antenna for this frequency. |
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Here's the other side of the V2.1.0 revision PCB. The antenna line on the front side aligns with the lower part of the first "L" in "LOLIN", and the matrix of vias further down obviously aligns with the ESP32-C3 chip. The PCB thickness is a bit less than 1 MM. Not seeing any line pattern, but IDK what may be going on in the middle layer. |
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I meant this part of the board That red part with "C3" on it, looks like a PCB soldered on top of the purple PCB. So on the other side of that 'red' PCB, there will likely be diagonal traces so you get something looking like a coil in 3D. As soon as the feed line leaves the area where it is wrapped in the ground plane, it is part of the antenna. |
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The C3 looks very much like this product, described as |
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Yep, surely looks like it.
However as you can see on that exact page you linked, there are quite strict requirements for the ground plane surrounding the antenna.
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Interesting video on this topic: https://www.youtube.com/watch?v=UHTdhCrSA3g And the linked blogpost: https://peterneufeld.wordpress.com/2025/03/04/esp32-c3-supermini-antenna-modification/ |
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Good morning :-) BUT MOST IMPORTANT: |
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As a crude and not at all "optimal" test, I hand-held a wire of suitable length to the "solder termination" end of the Rainsun "dummy component", and saw negative RSSI values for 7 AP improve significantly. |
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That seems to be a perfect situation: You do not have a chance to do anything to make it operate worse ;-) |
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@sfromis , not a good fix - we need you here with both hands free 😄 |
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Opened an issue in the Github repo for the board. Not very optimistic about them following it, but a breadcrumb is better than nothing. |
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!!!!!! WARNING FROM LOLIN C3 MINI !!!!!! Those boards have serious wifi issues!!!!!! tzapu/WiFiManager#1422 I have bought v2.1.0 and also v2.1.0 those have the issues! |
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!!!!!! WARNING FROM LOLIN C3 MINI !!!!!! Those boards have serious wifi issues!!!!!! tzapu/WiFiManager#1422 I have bought v2.1.0 and also v2.1.0 those have the issues! |
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These boards often suffer from a very bad designed and mismatched WiFi antenna circuit which even triggers the internal protection circuit. |
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no user got Tasmota working reliable. In the official Lolin Aliexpress shop there is feedback like this too.
No proper designed ESP32 board needs to reduce wifi tx power from the standard choosen from espressif https://www.wemos.cc/en/latest/c3/c3_mini.html#about-wifi
This is NOT a Tasmota problem. Tasmota does work well on every other board we and users have tried.
Imho the board has a hardware design problem, which can not solved by software.
Stay away from this board and try to get a refund.
EDIT a hardware mod is found to get it working. See #15443 (comment) Thx @hallard
EDIT 2
A better fix has been suggested here #15443 (reply in thread)
Jason2866
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