ESP8266 Send AT commands during setup()

On ESP8266 It would be handy to be able to set AT commands inside a sketch via the serial port to change wifi parameters. Any suggestions?

I am using an esp8266 with a serial-usb module, and the examples I've seen so far are using the esp8266 with an Arduino via TX/RX ports. Seems simple but it evades me.

Link to your ESP ? (Could it be one of those with NodeMCU already on it probably and not the basic expressif AT command firmware?)

So dumb question but how do I know if it's NodeMCU? I installed the following:

esp8266firmware\AT_v0.50_on_esp_iot_sdk_v1.4.0_150918\esp_iot_sdk_v1.5.0\bin\blank.bin
esp8266firmware\AT_v0.50_on_esp_iot_sdk_v1.4.0_150918\esp_iot_sdk_v1.5.0\bin\esp_init_data_default.bin
esp8266firmware\AT_v0.50_on_esp_iot_sdk_v1.4.0_150918\esp_iot_sdk_v1.5.0\bin\at\noboot\eagle.flash.bin
esp8266firmware\AT_v0.50_on_esp_iot_sdk_v1.4.0_150918\esp_iot_sdk_v1.5.0\bin\at\noboot\eagle.irom0text.bin

Did you get those from https://github.com/boseji/ESP-Store/tree/master/firmware and extracted from AT_v2.0.0_on_ESP8266_NonOS_SDK.zip??

When you flashed that firmware, did the installer confirm all was fine? if it is you should get an OK prompt by typing AT (ensuring the right GPIO pins are set correctly between programming and run mode)

does your unit (provide a link ?) looks more like the ones to the left or to the right?

It looks like the only way to access AT functions is by plugging it into an external processor. From the DOCS:

"One needs an additional processing unit with ESP8266 module such as Arduino, mbed, Raspberry Pi or any other embedded processor / board to perform the actual function. The ESP8266 module only provides connectivity via WiFi or able to host a WiFi network using the SoftAP function."

So I am trying to figure out if there's some way to change the ssid and password so that the user can plug it in, and change the ssid and password via the serial interface WITHOUT using an external processor.

Your quote is indeed true with the AT firmware; if you flash it with arduino code then you have a wifi capable arduino

change the ssid and password via the serial interface WITHOUT using an external processor

so how would you do that??

if your unit is running the AT firmware, then you need to send AT commands from a "computer" through the Serial line. That computer can be your PC, an Arduino etc...