WifiScan:: Weak signal reception compared to ESP8266

[tobozo]

Last month I received this ESP32S dev board from aliexpress and ran the WifiScan.ino example but the scan results are much worse than what I get when I scan with an ESP8266.

Instead of getting the usual amount of SSIDs (between 50 and 80 in my area), I only get two or three, and sometimes nothing. And the ESP32S is heating a bit more than the ESP8266.

There are no interferences, the ino code is similar, both ESP8266 and ESP32S had their code compiled and tested under the same circumstances.

After posting on reddit, someone suggested it could be a design error, so I ordered another model from aliexpress.

Today I've Just received this other board and it's exactly the same problem, displaying only 3 AP where the ESP8266 shows 50.

Now I'm wondering if there's some kind of setting that sets the Wifi to low power mode, or if I'm just unlucky in my model choices.

[Edit] Also tested on ESP32-Wrover-Kit (v3), ESPEA32, MH-ET-LIVE, D-Duino32

[me-no-dev]

What you describe is rather strange. I have a few 8266 and 32 boards here and will have a look. Though my area is not that noisy.

[tobozo]

More observations: when the ESP8266 sees an AP with -40db, both ESP32 models see the same AP with an RSSI between -60 and -70db.
There's an average 20db difference.
I took a photo of both models, maybe I've just bought a shitty clone or something.
I had some pins removed off the first model (the ones too close to the antenna) with no effect whatsoever.

[me-no-dev]

yeah,... what a horrible design... see how there is a board under the antenna? that should not be there at all.

[tobozo]

Yep free space is recommended, but 20db difference is a lot, it is the equivalent of having metal shielding. i.e. laptop casings can attenuate the signal more than 10db , but a piece of PCB shouldn't attenuate that much, otherwise Wemos D1 mini and other dev kits have a problem ?

Also the second model is ESP32 DEVKIT V1, aka "DOIT/SmartArduino ESP32 DevKit" is a recommended model from the sp32.net page, can I assume this one has a placement reasonable enough not to attenuate the signal by 20db ?

I've ordered a third model, same as the one you posted here.

[tobozo]

I just tried yet another ESP32 module, the ESPea32, and it behaves the same way.

@me-no-dev are you positive dev kits for ESP8266 and ESP32 should have the same reception quality for Wifi?
I'm starting to believe they don't, or that something hasn't been tuned-up yet somewhere in the toolchain.

[edit] added link

[me-no-dev]

@tobozo Will do my best to test this next week ;) I will be on a trip to help customers, but I'll have ESP8266 and ESP32 boards with me. Please ping back here around tuesday/wednesday so I do not forget :)

[tobozo]

(sorry for the misclose)

I just followed the tutorial to install micropython for esp32, then flashed the ESP32 and ran the wifi scan micropython code just to compare how many AP are returned.

I've run 10 scans per situation, here are the average values:

With the ESP32:

• Arduino IDE finds 15 AP
• Micropython finds 30 AP

With the ESP8266:

• Arduino IDE finds 60 AP
• Micropython finds 60 AP

[edit] If bad design on my ESP32 model affects RSSI, I still wonder why micropython returns more AP than an Arduino sketch. Speculation: BLE settings interfering with WiFi settings, scan loop exiting too fast ?

[me-no-dev]

interesting enough, there isn't any limitation imposed by the WiFi library in Arduino to how many APs are returned. Code is taken from the ESP8266 lib and only method calls are adapted. Maybe something default?

[tobozo]

I just found out that the gap between micropython and arduino is only observable in micropython after I make erase and make deploy.

Flashing with Arduino seems to cancel that effect.

If I make deploy micropython after a successful Arduino flash, there's no observable gap: the micropython library scan results give the same average as with Arduino.

Does it make sense the make erase somehow resets something that would allow me to enumerate more access points when using micropython ?

[me-no-dev]

There might be a setting that get's stored in NVS based on some config value maybe... and then does not get overridden unless you erase the flash

[tobozo]

Hey @me-no-dev I just received the same model as on your picture, and the quality/behaviour is the same as with the other models.

What settings should I be looking for? Is that part of Arduino, ESP-IDF or something else I should recompile?

[tobozo]

Could this be related