UDP broadcast (sent callback not getting called)

Posts: 2
Joined: Tue Dec 15, 2015 12:46 am

UDP broadcast (sent callback not getting called)

Postby Richard » Sat Feb 01, 2020 12:34 am

I am trying to use the esp8266 in soft ap mode to talk to another in station mode via a udp broadcast but several problems exist.

The esp8266 boards are close to each other so signal strength should not be an issue.

1] I am getting a large number of udp packets that are not being transmitted(90%). I am sending a packet every 300mS.
This is verified by what is received by the second esp8266 and also via a monitoring app on an ipad.

2) I do not get a call back when the packets are sent despite registering the callback. The receive callback does function.

Please can you advise if this is a bug in the RTOS firmware that I am using.
If not, can you advise how to debug this.
I have included the printout from the bootup sequence which shows the firmware and hardware versions.


ets Jan 8 2013,rst cause:2, boot mode:(3,6)

load 0x40100000, len 30460, room 16
tail 12
chksum 0xef
ho 0 tail 12 room 4
load 0x3ffe8000, len 1976, room 12
tail 12
chksum 0x61
ho 0 tail 12 room 4
load 0x3ffe87b8, len 2028, room 12
tail 0
chksum 0xfb
csum 0xfb
OS SDK ver: 2.0.0(5d55574) compiled @ Oct 22 2019 16:02:05
phy ver: 1056_9, pp ver: 10.7

rf cal sector: 1019
idle_task_hdl : 40107b38,prio:0, stack:384
tim_task_hdl : 40107c80, prio:2,stack:512

====SDK version:2.0.0(5d55574)
====Mem Info:
data : 0x3ffe8000 ~ 0x3ffe87b6, len: 1974
rodata: 0x3ffe87b8 ~ 0x3ffe8fa4, len: 2028
bss : 0x3ffe8fa8 ~ 0x3ffefa10, len: 27240
heap : 0x3ffefa10 ~ 0x40000000, len: 67056
====Free heap size:70200
====Chip ID:1577059

====system_get_cpu_freq 80MHz

EspMsgMutex created
wifi station disconnect ...... fail 0
ssid = TIMING_AP
IP Address:
Subnet mask:

mode : softAP(de:4f:22:18:10:63)
dhcp server start:(ip:,mask:,gw:
add if1
bcn 100

add 1
aid 1
station: 18:fe:34:da:80:b7 join, AID = 1
Station[1]: 18:fe:34:da:80:b7 join, AID = 1, 255

Her Mary
Posts: 493
Joined: Mon Oct 27, 2014 11:09 am

Re: UDP broadcast (sent callback not getting called)

Postby Her Mary » Fri Feb 28, 2020 10:19 am

1. Maybe you can try to put the ESP8266 board a little far from each other, 2m should be a suitable distance.
2. Maybe you can try with the latest version of RTOS. https://github.com/espressif/ESP8266_RT ... ls/sockets

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