Anyone using/tried the E28-2G4M27S 2.4Ghz LoRa SX1280 27dB module?
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A related topic is: just what kind of component is the antenna selector anyway?
My measurements suggest it is just a zero ohm resistor. It's very tiny, however, which makes it difficult to desolder and then re-solder to the right pads when changing the selection. I did do that on the receiver module, but on the transmitter module I removed the selector component and then used a solder bridge to enable the IPEX antenna connector and disable the trace antenna. -
Reporting back: Answering my own question about the retention force on u.fl connectors, it turns out you may get only 5 connects/disconnects before the connector is shot and needs replacing. Source:
https://www.youtube.com/watch?v=naJvFB52EtcSo, I'm guessing that why the u.fl connector on only my u.fl to sma adapter cable became loosey-goosey, as I described above. Fortunately, at least according to this source, the u.fl connector on the PCB doesn't wear out. It's just the cable connector side that does.
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Yes, the antenna selector is normally just a zero ohm resistor.
About the antenna sma connector: there are 4 connectors, not 2.
@mfalkvidd Thanks for that! So, it appears that what I need are the RP-SMA connectors, not the SMA connectors. All the wifi stuff is generally RP-SMA for instance. Yet another picture (duplicative of yours) to drive it home:
I had thought that maybe the threading was also different, but what I now gather that's not the case, as it wasn't needed to render the two standards incompatible. It's helpful to know that the RP-SMA standard was created for wifi, specifically so that wifi users wouldn't plug their wifi stuff into non-wifi stuff. Well, you potentially can, because the threading is the same, but you'll either get no joy from it or might even damage your connectors, because the inner connector will be the wrong gender. IMHO, they really should have changed the threading too as a further precaution and named it "reverse gender" instead of "reverse polarity", since polarity seemingly has nothing to do with it. i.e. the outer casing is ground in both standards, and the inner conductor is what carries the signal in both standards. But, they didn't, and now we have to live with it.Fun fact: what I was calling the number of "connect/disconnects" is technically referred to as the number of "mating cycles".
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@mfalkvidd Thanks for that! So, it appears that what I need are the RP-SMA connectors, not the SMA connectors. All the wifi stuff is generally RP-SMA for instance. Yet another picture (duplicative of yours) to drive it home:
I had thought that maybe the threading was also different, but what I now gather that's not the case, as it wasn't needed to render the two standards incompatible. It's helpful to know that the RP-SMA standard was created for wifi, specifically so that wifi users wouldn't plug their wifi stuff into non-wifi stuff. Well, you potentially can, because the threading is the same, but you'll either get no joy from it or might even damage your connectors, because the inner connector will be the wrong gender. IMHO, they really should have changed the threading too as a further precaution and named it "reverse gender" instead of "reverse polarity", since polarity seemingly has nothing to do with it. i.e. the outer casing is ground in both standards, and the inner conductor is what carries the signal in both standards. But, they didn't, and now we have to live with it.Fun fact: what I was calling the number of "connect/disconnects" is technically referred to as the number of "mating cycles".
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@NeverDie note that the picture you found has different naming for the RP variant than the picture I found.
RP-SMA male vs RP-SMA plug female socket
RP-SMA female vs RP-SMA jack male pinConfusion deluxe.
@mfalkvidd Good catch! I hadn't even noticed until you pointed it out. If even the people who make pictures meant to clarify are confused.....
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@mfalkvidd Good catch! I hadn't even noticed until you pointed it out. If even the people who make pictures meant to clarify are confused.....
@NeverDie the rule I learned (which is not politically correct, but memorable) is that the male always does the screwing and if the male doesn't have a d**k it's reverse polarity.
The key here is to not focus on the signal connector, but on the mating. The female versions are fixed, the male versions screw on to the female.
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@NeverDie the rule I learned (which is not politically correct, but memorable) is that the male always does the screwing and if the male doesn't have a d**k it's reverse polarity.
The key here is to not focus on the signal connector, but on the mating. The female versions are fixed, the male versions screw on to the female.
@mfalkvidd After checking just now what's for sale on amazon, your picture seems to be the right one. However, that phrase you have is bringing me to the wrong conclusion (the picture I posted). I mean, consider the RP-SMA female connector picture (referring to the picture you posted). You would think that would be male if anything is if that phrase was right. I mean, it screws "into" something else, and it has a d**k. Yet, evidently, its proper designation is female. Go figure.
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@mfalkvidd After checking just now what's for sale on amazon, your picture seems to be the right one. However, that phrase you have is bringing me to the wrong conclusion (the picture I posted). I mean, consider the RP-SMA female connector picture (referring to the picture you posted). You would think that would be male if anything is if that phrase was right. I mean, it screws "into" something else, and it has a d**k. Yet, evidently, its proper designation is female. Go figure.
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@NeverDie no. It doesn’t screw into anything. It is fixed. It cannot be turned without turning the entire cable. Hence the male is the one doing the screwing. The male variant can turn without turning the cable.
@mfalkvidd Thanks! It finally makes sense now that you've explained it like that.
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Which thickness of coax cable should one prefer? Is thicker generally better? For instance, here are two connector cables of the same type, and both 50 ohm, but one is 0.81mm coax, and the other is 1.13mm coax. Does the difference matter?
https://www.amazon.com/gp/product/B098QGFZ2J/ref=crt_ewc_title_dp_3?ie=UTF8&psc=1&smid=AODZVW3FCSGNT
https://www.amazon.com/gp/product/B098QF5XF8/ref=crt_ewc_title_dp_1?ie=UTF8&psc=1&smid=AODZVW3FCSGNT
[Edit: I do notice that they have different IPEX connectors, but I'm wondering just about the coax diameter.]
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I'll see it through to the end, but I think at this point Ebyte 2.4Ghz LoRa is now academic. With all this antenna nonsense getting in the way of a simple, inexpensive solution, it just doesn't hold a candle to a fully integrated solution, like this simple, compact LoRa gateway, where even a simple spring antenna is sufficient:
The shield on top can be demounted and is a fully-standalone atmega328p driving the LoRa radio, which makes for a complete solution that's not much larger than the AI-Thinker module itself! I'll just drop a 915Mhz Ai-Thinker LoRa module into place instead of the 433Mhz module currently there, and, bang, it should "just work."
I suppose desoldering the IPEX connector on the EBYTE module I could perhaps make a short jumper run from a custom PCB onto the EBYTE antenna pad..... Hmmm.... Kludgy, but it might work. In contrast, however, with the AI-Thinker modules there's a through-hole already set aside for a whip antenna.
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Which thickness of coax cable should one prefer? Is thicker generally better? For instance, here are two connector cables of the same type, and both 50 ohm, but one is 0.81mm coax, and the other is 1.13mm coax. Does the difference matter?
https://www.amazon.com/gp/product/B098QGFZ2J/ref=crt_ewc_title_dp_3?ie=UTF8&psc=1&smid=AODZVW3FCSGNT
https://www.amazon.com/gp/product/B098QF5XF8/ref=crt_ewc_title_dp_1?ie=UTF8&psc=1&smid=AODZVW3FCSGNT
[Edit: I do notice that they have different IPEX connectors, but I'm wondering just about the coax diameter.]
@NeverDie The characteristic impedance of the coax is what matters. And that is all determined by the construction, which includes the thickness, but also other things, like what dielectric, and probably even what metal is used. (I don't know all the variables that they have to play with.)
So it could be that both of those options you posted are fine. But buying stuff like this on Amazon, especially through third parties is a crap shoot. No telling if it will be good or not, and the reviews aren't usually very helpful, either, on RF stuff. Not saying you shouldn't do it - I will gamble myself, but just go in fully aware that your chances of getting something shoddy are good, and make sure the price you pay is worth the gamble.
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@NeverDie The characteristic impedance of the coax is what matters. And that is all determined by the construction, which includes the thickness, but also other things, like what dielectric, and probably even what metal is used. (I don't know all the variables that they have to play with.)
So it could be that both of those options you posted are fine. But buying stuff like this on Amazon, especially through third parties is a crap shoot. No telling if it will be good or not, and the reviews aren't usually very helpful, either, on RF stuff. Not saying you shouldn't do it - I will gamble myself, but just go in fully aware that your chances of getting something shoddy are good, and make sure the price you pay is worth the gamble.
@ejlane Agreed. Where is it that you prefer to shop?
A lot of the amazon stuff is the same as what one might find on Aliexpress, but the difference is I can get it fast and with free shipping from Amazon, and returns are a breeze. When it comes to quality, I think Mouser or Digikey usually has the best, but at usually higher prices even before you figure in shipping. Is there anywhere else worth considering? Maybe there's a good resource I've overlooked.
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@ejlane Agreed. Where is it that you prefer to shop?
A lot of the amazon stuff is the same as what one might find on Aliexpress, but the difference is I can get it fast and with free shipping from Amazon, and returns are a breeze. When it comes to quality, I think Mouser or Digikey usually has the best, but at usually higher prices even before you figure in shipping. Is there anywhere else worth considering? Maybe there's a good resource I've overlooked.
@NeverDie I think you've pretty much covered it. Yes, sometimes there's no good hobby-level alternative to Amazon/Aliexpress if you want it cheap.
Though someplace like SparkFun or Adafruit can be good for hobbyists, though you'll pay for it.
Along with Mouser and Digikey, sometimes I have good luck with Arrow or Newark. But really, it's nice to do a search with octopart.com or findchips.com if you have a pretty good idea of what you want. They will look at lots of vendors, even some that might be shading towards gray market. Can really save some time, and sometimes find things that I never would have otherwise. Saved me a few months ago on a customer project that would have otherwise had to be completely redesigned.
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Reporting back: Today I received proper IPEX to RP-SMA connector cable. I hooked up both the transmitter and receiver using them to the factory recommended 2.4ghz antennas. The transmitter and receiver are two rooms apart, and the signal has to pass through two closed doors. What I'm getting doesn't look great:
4s PacketError,RSSI,-74dBm,SNR,-4dB,Length,23,Packets,0,Errors,1,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 7s PacketError,RSSI,-79dBm,SNR,-15dB,Length,23,Packets,0,Errors,2,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 9s PacketError,RSSI,-77dBm,SNR,-11dB,Length,23,Packets,0,Errors,3,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 12s PacketError,RSSI,-73dBm,SNR,-1dB,Length,23,Packets,0,Errors,4,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 13s Hello World 1234567890*,CRC,DAAB,RSSI,-78dBm,SNR,-6dB,Length,23,Packets,1,Errors,4,IRQreg,8012 14s PacketError,RSSI,-79dBm,SNR,-8dB,Length,23,Packets,1,Errors,5,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 16s PacketError,RSSI,-78dBm,SNR,-4dB,Length,23,Packets,1,Errors,6,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 18s PacketError,RSSI,-82dBm,SNR,-17dB,Length,23,Packets,1,Errors,7,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 26s PacketError,RSSI,-80dBm,SNR,-22dB,Length,23,Packets,1,Errors,8,IRQreg,8020,IRQ_HEADER_ERROR,IRQ_PREAMBLE_DETECTED 28s PacketError,RSSI,-79dBm,SNR,-9dB,Length,23,Packets,1,Errors,9,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 31s PacketError,RSSI,-85dBm,SNR,-19dB,Length,23,Packets,1,Errors,10,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 32s PacketError,RSSI,-83dBm,SNR,-7dB,Length,23,Packets,1,Errors,11,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 35s Hello World 1234567890*,CRC,DAAB,RSSI,-77dBm,SNR,-8dB,Length,23,Packets,2,Errors,11,IRQreg,8012 37s PacketError,RSSI,-82dBm,SNR,-15dB,Length,23,Packets,2,Errors,12,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 50s Hello World 1234567890*,CRC,DAAB,RSSI,-81dBm,SNR,-17dB,Length,23,Packets,3,Errors,12,IRQreg,8012 51s Hello World 1234567890*,CRC,DAAB,RSSI,-81dBm,SNR,-12dB,Length,23,Packets,4,Errors,12,IRQreg,8012 54s PacketError,RSSI,-79dBm,SNR,-4dB,Length,23,Packets,4,Errors,13,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 57s Hello World 1234567890*,CRC,DAAB,RSSI,-74dBm,SNR,-6dB,Length,23,Packets,5,Errors,13,IRQreg,8012 60s PacketError,RSSI,-78dBm,SNR,-14dB,Length,23,Packets,5,Errors,14,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 62s Hello World 1234567890*,CRC,DAAB,RSSI,-75dBm,SNR,-6dB,Length,23,Packets,6,Errors,14,IRQreg,8012 67s PacketError,RSSI,-84dBm,SNR,-20dB,Length,23,Packets,6,Errors,15,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 69s PacketError,RSSI,-78dBm,SNR,-12dB,Length,23,Packets,6,Errors,16,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 72s Hello World 1234567890*,CRC,DAAB,RSSI,-77dBm,SNR,-11dB,Length,23,Packets,7,Errors,16,IRQreg,8012 76s PacketError,RSSI,-79dBm,SNR,-13dB,Length,23,Packets,7,Errors,17,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 78s Hello World 1234567890*,CRC,DAAB,RSSI,-79dBm,SNR,-12dB,Length,23,Packets,8,Errors,17,IRQreg,8012 80s Hello World 1234567890*,CRC,DAAB,RSSI,-76dBm,SNR,-7dB,Length,23,Packets,9,Errors,17,IRQreg,8012 83s PacketError,RSSI,-75dBm,SNR,-7dB,Length,23,Packets,9,Errors,18,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 86s PacketError,RSSI,-78dBm,SNR,-6dB,Length,23,Packets,9,Errors,19,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 103s PacketError,RSSI,-76dBm,SNR,-18dB,Length,23,Packets,9,Errors,20,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 105s PacketError,RSSI,-81dBm,SNR,-18dB,Length,23,Packets,9,Errors,21,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 108s PacketError,RSSI,-79dBm,SNR,-3dB,Length,23,Packets,9,Errors,22,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTED 109s Hello World 1234567890*,CRC,DAAB,RSSI,-78dBm,SNR,-3dB,Length,23,Packets,10,Errors,22,IRQreg,8012 110s Hello World 1234567890*,CRC,DAAB,RSSI,-79dBm,SNR,-6dB,Length,23,Packets,11,Errors,22,IRQreg,8012 112s PacketError,RSSI,-78dBm,SNR,-3dB,Length,23,Packets,11,Errors,23,IRQreg,8052,IRQ_RX_DONE,IRQ_HEADER_VALID,IRQ_CRC_ERROR,IRQ_PREAMBLE_DETECTEDI think maybe the breadboard construction and long wires are introducing too much unwanted signals, resulting in lowered performance. The only way I can think of to get rid of that would be to make a specialty PCB that puts an atmega328p in close proximity with the module, so that there aren't long wires or long traces to pick up noise along the way.Or, maybe it's something else. In any case, I'm going to pause this and switch-over to a 915Mhz AI-Thinker module to see whether I get more traction there. -
Re-thinking this, probably the easiest way to exclude whether or not the breadboarding and related wiring is a crippling source of noise would be to create a PCB that an Arduino Pro Mini can dock with and which makes all the needed connections directly to the E28-2G4M27S. It's so easy that I should have thought of it in the first place! I have started work on it, and I'll post a rendering when its ready. I may post it in openhardware.io, and I think I may take a similar approach to future breakout boards as well. Pro-mini's are so cheap that it will make for a good way to test different radio modules.
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What happened to prices? I checked just now and pro mini's are selling for $5+. Pre-pandemic they could be had for closer to $1.
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What happened to prices? I checked just now and pro mini's are selling for $5+. Pre-pandemic they could be had for closer to $1.
@NeverDie Haven't you heard of the chip shortage? It's changed everything, and prices for those things that are even available have generally gone up. (Though somehow magically, the ESP32 seems to be pretty much untouched. You can still buy them, and prices have been relatively stable. I don't know how they've done it.) AVR, PIC, STM chips have all been hard to get specific models, and at times any model that has the features. I expect other brands were similar, but those are the ones that I've looked for.
I hope they someday go back, but for the foreseeable future, expect it to be like this.
Pro minis for close to $1 was always a shock, since even at 1k qty, just the chip itself costs more than that. So to get to that price for the whole assembled board, there must be some kind of gray-market thing going on. If I were to try to make a profit on 1k at a time, assembled and everything, I'm pretty sure the final price would have to be in the ballpark of $10 each.
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@NeverDie Haven't you heard of the chip shortage? It's changed everything, and prices for those things that are even available have generally gone up. (Though somehow magically, the ESP32 seems to be pretty much untouched. You can still buy them, and prices have been relatively stable. I don't know how they've done it.) AVR, PIC, STM chips have all been hard to get specific models, and at times any model that has the features. I expect other brands were similar, but those are the ones that I've looked for.
I hope they someday go back, but for the foreseeable future, expect it to be like this.
Pro minis for close to $1 was always a shock, since even at 1k qty, just the chip itself costs more than that. So to get to that price for the whole assembled board, there must be some kind of gray-market thing going on. If I were to try to make a profit on 1k at a time, assembled and everything, I'm pretty sure the final price would have to be in the ballpark of $10 each.
@ejlane & @NeverDie: Amazing technology that was available for $1 was … too hard to believe. Even $5 for a ProMini is pretty mind-blowing. Not that I buy commodities, I do buy these components a dozen at a time to save on shipping even when it is ‘free’. I laugh at myself when I spend a week of my time on a $2 chip and then wonder how I can rework it from a PCB (never worth the attempt). Compared to any other hobby or habit this radio-electronic stuff is cheaper than cooking top-ramen at home.
BTW, thanks for the radio discussion posted last week. I will read and learn later.
