How many clients can connect in Access point mode

[STASIUK]

How many clients can connect to the module in Access point mode?

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[acoulson2000]

anyone?

[Links2004]

4 clients are possible right now.
https://github.com/esp8266/Arduino/blob/esp8266/hardware/esp8266com/esp8266/libraries/ESP8266WiFi/src/ESP8266WiFi.cpp#L267

[acoulson2000]

It seems like it is possible to call wifi_softap_set_config() with a config.max_connections value greater than 4 to override the default? Do you know if this is, in fact the case, and what the ramifications might be? I understand that more clients require more RAM, but from googling around, it's not clear how much. I have a relatively simple host app which I would like to use to send UPD broadcasts to many clients.

I appreciate any sight,
Andy

[Links2004]

you can try it, if its working we can add an API to change the value.
keep in mind the TCP sockets are limited to 5 and the UDP sockets to 4 form the SDK.
but multicast / broadcasts shut reaches all with one socket.

[acoulson2000]

Markus,

Thanks for you're feedback. I'm not very C-savy and certainly the whole ESP8266 toolchain is a bit intimidating. To try it, is it necessary to modify the source code and build the firmware? Or can I simply set up my own config structure and pass it in from my own user code using something like below? I ask because your response regarding the possibility of providing an API seems to imply this will not work.

struct softap_config cfgESP;
//.... set ssid, auth, etc
cfgESP.max_connection=32;
// ....
wifi_softap_set_config(&cfgESP);

Thanks again,
Andy

[Links2004]

you can use the SDK directly like you shown.

to use the SDK you need to do the include like this:

extern "C" {
#include "user_interface.h"
}

if its working i will add it to the begin function of the AP, so it will be easy to use with out to deal with the SDK.

[bren3582]

Any luck @acoulson2000? I'd like to increase the number of connections for my project if possible.

[acoulson2000]

So far, I have only connected 3 simultaneously, but so far, so good. It will probably be a couple of weeks at least before I'm ready to try more, but I'll post back with my results.

[bertamf]

Hi @acoulson2000! I've also been trying to connect more than 4 devices to the AP, but I haven't succeed so far. What about you?
Thanks!

[acoulson2000]

@brianensor and @bertamf, sorry, I still have not tried this. I went up working with NodeMCU for my project, and even then, I only got up to exactly 4 clients (this was for the Christmas project I've begun describing here https://austinlightguy.wordpress.com/2016/01/24/lightsuit-v2/). I've started playing around with some stuff I postponed during the busy holidays, though, so I hope to investigate this again shortly and will post my findings. First, I will probably just try it with my NodeMCU AP and clients, then I'll try an Arduino version. One issue I do have is that I only get a packet throughput rate of something like 8-10Hz and I'm wondering if the Arduino code, which will be more like native, will be faster.

[alx-1]

I can edit user_interface.h if someone knows how to pass a higher value to max_connection :
uint8 max_connection; // Note: default 4, max 4
I don't know C but I have 8 ESP8266's to test it with. @acoulson2000, I like your light suit! We're working on controlling 8 radios from relays connected to carbon monoxyde pollution.https://github.com/reseauducommun/CarboBlaster

[acoulson2000]

So, I've started playing around with this a bit again. I was using my NodeMCU code, but was finding that I got a lot of random reboots on my UDP receiver. I think possibly this is because it's also doing a lot of work pumping the WS2812 data for about 300 LEDs across GPIO2 (although this is supposed to be very effiecient with the UART-driven fix (nodemcu/nodemcu-firmware#951) for that driver.)

I have switched to Arduino, but so far am only up to three clients. I'll rig a couple more up within a few days. So far, I have not added the WS2812 functionality in, so I'm not sure what the stability will look like.

One thing I've definitely determined - pumping packets at high speed, even via UDP multicast, does not work very well when the sender is configured in AP mode. I guess it's too busy handling the WiFi stack and just managing WiFi clients or something, but when I configure it that way, my clients all seem to receive packets in "clumps" - so they'll get something like 4 to 6 packets, then experience a slight delay, then receive another clump. The overall throughput is decent, but for my application I really want a consistent, high-speed stream of packets, since my clients are essentially remote VU meters. When I configure both the sender and receivers to all connect to my home wifi in WIFI_STA mode, I get much more consistent streaming at about 10hz (4 byte packets). With my phone as a tethering AP, it's not as good as my home router, but still better than an ESP8266 in AP mode.

@alx-1, I think the idea is that you may not have to modify existing SDK code, you just include the header file at the top of your sketch wit this:
extern "C" {
#include "user_interface.h"
}

then something like this in setup() of your sketch:
struct softap_config config;
wifi_softap_get_config(&config); // Get config first.

os_memset(config.ssid, 0, 32);
os_memset(config.password, 0, 64);
os_memcpy(config.ssid, "ESP8266", 7);
os_memcpy(config.password, "12345678", 8);
config.authmode = AUTH_WPA_WPA2_PSK;
config.ssid_len = 0;// or its actual length
config.beacon_interval = 100;
config.max_connection = 8; // how many stations can connect to ESP8266 softAP at most.

wifi_softap_set_config(&config);// Set ESP8266 softap config

Now that I look at this, I wonder if fiddling witht the beacon_interval might help my in AP mode...

[NikhilMJ]

@acoulson2000 : Any progress on this? I have an application that requires 4-8 ESPs that are sent commands from a single ESP configured in AP mode.

EDIT: I was hoping to find a UDP broadcast solution that reliably worked with a high enough update rate, but wasn't able to find one. Any suggestions?

[acoulson2000]

@NikhilMJ , not sure if you're still interested in this issue, but in case you or anyone else who runs across this thread is, I do have something to report.

While I never got around to trying this with the ESP8266, that is in part because I found that the packet rate from an ESP8266 in AP mode was really quite low. Using the ESP8266 as the AP, I was able to broadcast small (5 byte) packets at around 1 every 150-to-200ms. Connecting to a separate, dedicated AP (just a very cheap WiFi router), I got almost double. Since my project needs to be wearable, I didn't really pursue this option.

HOWEVER, now that the ESP32 is available, I decided to revisit it. It even turns out that, alhtough the default for ESP32 is still 4, there was a recent commit to the ESP32 SDK that supports changing the maximum. Using Sparkfun ESP32 thing with the extended API - which is WiFi.softAP(ssid, passphrase, channel, ssid_hidden, max_connection) - I have been able to set max_connections to 16 and have so far connected 6 clients simultaneously, with a throughput of 40 packets per second (25ms/packet)! Hooray for the ESP32!