| 摘要 |
In a remote battery operated keyboard entry device coupled to a microcomputer (1) through an infra-red link, the drive transistor (10, 17) for an infra-red LED (5) is coupled to receive serial pulses representing keystrokes through a network including a visible LED (14). The arrangement is such that for each input pulse, the visible LED is turned on to provide a visible transmission indication and also an input reference potential to determine the amplitude of the current drive of the transistor through the infra-red LED to guard against data loss caused by battery droop. |
