Embedded things: ESP-C3-12F First power-up

Just received ESP-C3-12F. With "C3FN4" marked on the module shield, that means it have Build-in 4MByte FLASH. ESP-C3-12F is a Wi-Fi module developed by Ai-Thinker. This module core processor ESP32-C3 is a Wi-Fi+ BLE combination of system-level chips (SoC).

In order to use the ESP-C3-12F, I solder it on a special multi-function PCB for ESP-12F (or called "diymore ESP8266 ESP-12E ESP-12F ESP32 Double Side Prototype PCB Board").

I also add buttons of RESET and BOOT connect EN and IO9 (same position of IO0 on ESP-12F), to force it entering BOOTLOADER mode for using with esptool.

It's strongly recommended using separate 3V3 Power Supply for ESP-C3-12F. A USB to Serial Breakout (FT232RL) in 3V3 operation mode is used to connect to ESP-C3-12F.

In my practice, the connection is:

USB-to-Serial (FT232RL)   ESP-C3-12F
(in 3V3 mode)
RX                        TX0
TX                        RX0
GND                       GND

RESET BUTTON              EN/GND
BOOT BUTTON               IO9/GND

Separate Power Supply
+3V3                      VCC
GND                       GND

log of esptool output:

pi@raspberrypi:~ $ esptool.py --chip auto --port /dev/ttyUSB0 chip_id
esptool.py v3.1
Serial port /dev/ttyUSB0
Connecting........_____....._
Detecting chip type... ESP32-C3
Chip is unknown ESP32-C3 (revision 3)
Features: Wi-Fi
Crystal is 40MHz
MAC: 84:f7:03:a5:10:94
Uploading stub...
Running stub...
Stub running...
Warning: ESP32-C3 has no Chip ID. Reading MAC instead.
MAC: 84:f7:03:a5:10:94
Hard resetting via RTS pin...
pi@raspberrypi:~ $ esptool.py --chip auto --port /dev/ttyUSB0 flash_id
esptool.py v3.1
Serial port /dev/ttyUSB0
Connecting...
Detecting chip type... ESP32-C3
Chip is unknown ESP32-C3 (revision 3)
Features: Wi-Fi
Crystal is 40MHz
MAC: 84:f7:03:a5:10:94
Stub is already running. No upload is necessary.
Manufacturer: 20
Device: 4016
Detected flash size: 4MB
Hard resetting via RTS pin...
pi@raspberrypi:~ $

log of AT Command:

ESP-ROM:esp32c3-api1-20210207
Build:Feb  7 2021
rst:0x1 (POWERON),boot:0xc (SPI_FAST_FLASH_BOOT)
SPIWP:0xee
mode:DIO, clock div:2
load:0x3fcd6100,len:0x147c
load:0x403ce000,len:0x91c
load:0x403d0000,len:0x2838
entry 0x403ce000

################################################
arch:ESP32C3, 3
compile_time:Ai-Thinker|B&T
ble_mac:84F703a51096
wifi_mac:84F703a51094
sdk_version:v4.3-beta3-195-g6be10fab0
firmware_version:2.2.0
compile_time:Jul  5 2021 13:46:35

ready

################################################AT

OK
AT

OK
AT+GMR
AT version:2.2.0.0(s-90458f0 - ESP32C3 - Jun 18 2021 10:24:22)
SDK version:v4.3-beta3-195-g6be10fab0
compile time(5fb0957):Jul  5 2021 13:46:35
Bin version:2.2.0(MINI-1)

OK
AT+RST

OK
ESP-ROM:esp32c3-api1-20210207
Build:Feb  7 2021
rst:0xc (RTC_SW_CPU_RST),boot:0xc (SPI_FAST_FLASH_BOOT)
Saved PC:0x40383888
SPIWP:0xee
mode:DIO, clock div:2
load:0x3fcd6100,len:0x147c
load:0x403ce000,len:0x91c
load:0x403d0000,len:0x2838
entry 0x403ce000

################################################
arch:ESP32C3, 3
compile_time:Ai-Thinker|B&T
ble_mac:84F703a51096
wifi_mac:84F703a51094
sdk_version:v4.3-beta3-195-g6be10fab0
firmware_version:2.2.0
compile_time:Jul  5 2021 13:46:35

ready

################################################

Remark:

Actually, I'm confussed.

According to ESP-AT v2.2.0.0_esp32c3 User Guide, AT Command should be sent to UART1 (GPIO6/GPIO7). But in my test as shown in the video. Both esptool and AT Command are sent to UART0 (GPIO20/21).

Or, is it AI-Thinker firmware have different port usage?