pub(super) fn set_up_modular_multiplication(&mut self, operand_b: &T::InputType) {
        self.rsa.write_multi_start();
        self.rsa.wait_for_idle();

        self.rsa.write_operand_a(operand_b);
    }
Starts the modular multiplication operation.

For more information refer to 24.3.2 of <https://www.espressif.com/sites/default/files/documentation/esp32_technical_reference_manual_en.pdf>.
esp-hal/src/rsa/esp32.rs