Uart; Strapping Pins - Espressif Systems ESP32-C6 Series Hardware Design Manuallines

2 Schematic Checklist
Notice:
The matching parameters vary with board, so the ones used in our modules could not be applied directly.

2.6 UART

It is recommended to connect a 499 Ω series resistor to the U0TXD line in order to suppress the 80 MHz
harmonics.
Usually UART0 is used as the serial port for download and log printing, and UART0 pins are fixed. For
instructions on download over UART0, please refer to Section 4.3.
Other UART interfaces can be used as serial ports for communication, which could be mapped to any available
GPIO by software configurations. For these interfaces, it is also recommended to add a series resistor to the TX
line to suppress harmonics.

2.7 Strapping Pins

At each startup or reset, a chip requires some initial configuration parameters, such as in which boot mode to
load the chip, etc. These parameters are passed over via the strapping pins. After reset, the strapping pins
operate as regular IO pins.
All the information about strapping pins is covered in
Pins.
In this document we will mainly cover the strapping pins related to boot mode.
GPIO8 and GPIO9 control the boot mode after the reset is released. See Table
Control.
Espressif Systems
Figure 11: RF Tuning Diagram
ESP32-C6 Series Datasheet
14
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> Section Strapping
3 Boot Mode Control Boot Mode
ESP32-C6 Series Hardware Design Guidelines v1.0