Change sketch upload speed

Projects Networking, Protocols, and Devices
1

Hi, I've a Mega2560+ESP8266 WiFi R3 board that the baud rate of ESP8266 serial interface is 74880.
when I try to upload sketch to ESP8266, in the tools menu under upload speed, there is not 74880 speed and with selecting 115200, the IDE can't connect to ESP8266.
how can I add and select 74880 rate for sketch upload of ESP8266?

I want to upload sketch and change the default AT command firmware in flash of ESP because when connect to it by Arduino IDE serial monitor and choose 74880 baud rate, receive some data from the chip but the end lines are garbage characters and also can't send any AT command to it, the communication is in one-way.
the data I receive is like this:

ets Jan 8 2013,rst cause:2, boot mode:(3,7)

load 0x4010f000, len 1384, room 16
tail 8
chksum 0x2d
csum 0x2d
v00000000
~ld
after this line, only have garbage characters.
Unfortunately the ESP Flash Download tool does not support baud rates under 115200 too and can't flash the firmware for resolving the problem.

2

I have no experience of your board, but 74880 is a rather oddball baud rate. Did the board come configured for that baud rate?

EDIT: I just did a quick Google search for 74880 baud and there are several discussions about ESP8266 and that baud rate.

3

I found the baud rate after some try because the default of ESP chips is mostly set to 115200 but when I choose this rate, the serial monitor scroll bars move without showing any characters. so I changed the baud rate to each number and receive this characters only in this rate.

this is the link of my board : https://robotdyn.com/mega-wifi-r3-atmega2560-esp8266-flash-32mb-usb-ttl-ch340g-micro-usb.html

this board have some dip switch to control working mode. may be the default baud rate changed in my own trying for uploading sketch to Mega2560 MCU and mistake in changing Dip switches.

4

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