Detailed explanation of GPIO configuration for ODR, BSRR, and BRR.

ODR, BSRR, and BRR are registers used for configuring GPIO pins, allowing for the setting and clearing of specific GPIO pins.

1. ODR (Output Data Register): This register is used to control the output state of GPIO pins. Each pin corresponds to a bit, and the output state of a pin can be set by setting or clearing the corresponding bit, either to a high level or low level. A bit set to 1 indicates a high level output, while a bit set to 0 indicates a low level output.
2. The BSRR (Bit Set/Reset Register) is used to set or clear the output status of GPIO pins. Similar to the ODR register, each pin corresponds to a bit, but the BSRR register has more functions. When a bit is set to 1, it indicates setting the pin to a high-level output; when a bit is set to 0, it indicates setting the pin to a low-level output. At the same time, by setting the corresponding bits, you can set a pin to a high or low-level output while keeping other pins in their original states, i.e. without changing their output status.
3. Bit Reset Register (BRR): This register is used to clear the output state of GPIO pins, setting the pins to low-level output. Each pin corresponds to a bit, where a bit set to 1 indicates the pin is set to low-level output; a bit set to 0 maintains the pin’s original state.

In summary, the ODR, BSRR, and BRR registers play a role in setting and clearing the output status of GPIO pins in configuration. By using these registers, it is possible to set or clear the corresponding bits to configure GPIO pins as high level output, low level output, or maintain their original state.