Fábio Coutada
98ed638f3c
All uncommitted work from ESP32 GDB stub development session. Includes: - GDB stub (uos_gdbstub.c/.h/_entry.S) - Startup vector table rewrite - ESP32 HAL integration files - Boot chain design docs - AGENTS.md absolute rules (commit before refactor, no unauthorized changes) - All prior deepseek session work This commit prevents further data loss. No claims of correctness. |
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| README.md | ||
GPIO API usage in Peripheral Drivers
When a peripheral driver initializes IOs, the general rule is to append necessary configurations onto the IO, instead of using any GPIO APIs that overwrite the current IO setting, such as gpio_config, gpio_reset_pin, gpio_set_direction, gpio_set_pull_mode.
Use gpio_pullup_en and gpio_pulldown_en to enable the internal pull-up/pull-down resistors if necessary.
Use gpio_od_enable to configure an output IO as open-drain mode if necessary.
Configure an IO as a peripheral signal output
There is no need to enable the output for the IO explicitly, it is done internally in the following function calls.
If the signal is routed through IO MUX to the pin, then only needs to call gpio_iomux_output to select the IO MUX function index. Output enable is controlled by the signal itself.
If the signal is routed through GPIO Matrix to the pin, then call gpio_matrix_output to select the PIN_FUNC_GPIO function and connect the signal to the pin.
When a peripheral driver does de-initialization, to de-configure the pin as the peripheral signal output, a call to gpio_output_disable is enough. It will disconnect the signal internally.
Configure an IO as a peripheral signal input
If the signal is routed through IO MUX to the pin, then only needs to call gpio_iomux_input to select the IO MUX function index and direct the signal to IO MUX. Input will be enabled for the IO internally.
If the signal is routed through GPIO Matrix to the pin, then call gpio_matrix_input to enable the input and connect the signal to the pin.
When a peripheral driver does de-initialization, to de-configure the pin as the peripheral signal input, use esp_rom_gpio_connect_in_signal to connect the signal to CONST_ONE or CONST_ZERO, so that it is disconnected from the pin. It is not desired to call gpio_input_disable, because there might be other drivers still using this pin as an input.
Configure an IO as analog function
When the pin is used for analog purpose, the pin needs to be left floating, so that the external analog signal is directly connected to internal analog signal. A call to gpio_config_as_analog will handle all the necessary IO configurations.