Information sending device, information receiving device, and information transmission system

The embodiment of the invention discloses an information sending device, an information receiving device and an information transmission system, and belongs to the field of computers. In the embodiment of the invention, a first signal output by an UART interface is transmitted to a signal switching circuit, and the signal switching circuit outputs a third signal without level change under the condition that the signal switching circuit is not connected with a signal restoring circuit, and only under the condition that the signal switching circuit and the signal restoring circuit are matched for use, a second signal can be output to the signal restoring circuit for signal restoration. Therefore, even if the output end of the signal switching circuit is connected with analysis equipment suchas an oscilloscope or a logic analyzer, any signal waveform cannot be measured, decryption cannot be carried out according to the measured signal waveform to obtain decrypted information, and the situation that the informati