A method of short-range data transmission between a portable electronic device for storage and short-range data transmission, comprising a power source , a microcontroller , a memory circuit , and a radio transceiver , and another device of this type or a stationary device, characterized in that the portable electronic device comprises a photoelectric sensor exposed to ambient light through a reference surface of the device , and a spatial orientation sensor defining the reference vector (N) of the device , wherein the method comprises the steps of (a) measuring the intensity of the light incident on the reference surface ; (b) awakening the microcontroller if the light intensity measured in step (a) is lower than a predefined threshold (P) and determining the reference vector direction (N); (c) turning on the radio transceiver if the reference vector (N) is inclined relative to the gradient vector of the gravitational field by an angle within a predefined range of inclination angles, and preferably substantially parallel to the gradient vector of the gravitational field; and (d) starting a data sending session from the memory circuit if the reference vector (N S ) is pointing within a predefined range of first directions, or starting a data receiving session to the memory circuit if the reference vector (N R ) is pointing within a predefined range of second directions, wherein said range of second directions is different, and preferably substantially opposite, to said range of first directions. a photoelectric sensor exposed to ambient light through a reference surface of the device , and a spatial orientation sensor defining the reference vector (N) of the device , wherein the method comprises the steps of (a) measuring the intensity of the light incident on the reference surface ; (b) awakening the microcontroller if the light intensity measured in step (a) is lower than a predefined threshold (P) and determining the reference vector direction (N); (c) turning on the radio transceiver if the reference vector (N) is inclined relative to the gradient vector of the gravitational field by an angle within a predefined range of inclination angles, and preferably substantially parallel to the gradient vector of the gravitational field; and (d) starting a data sending session from the memory circuit if the reference vector (N S ) is pointing within a predefined range of first directions, or starting a data receiving session to the memory circuit if the reference vector (N R ) is pointing within a predefined range of second directions, wherein said range of second directions is different, and preferably substantially opposite, to said range of first directions. (a) measuring the intensity of the light incident on the reference surface ; (b) awakening the microcontroller if the light intensity measured in step (a) is lower than a predefined threshold (P) and determining the reference vector direction (N); (c) turning on the radio transceiver if the reference vector (N) is inclined relative to the gradient vector of the gravitational field by an angle within a predefined range of inclination angles, and preferably substantially parallel to the gradient vector of the gravitational field; and (d) starting a data sending session from the memory circuit if the reference vector (N S ) is pointing within a predefined range of first directions, or starting a data receiving session to the memory circuit if the reference vector (N R ) is pointing within a predefined range of second directions, wherein said range of second directions is different, and preferably substantially opposite, to said range of first directions. <EOS>