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6.8
Digital Inputs (Labelled 1DS and 2DS)
The SSP has two push buttons, connected to digital input channels 1 and 2 respectively. The program
can read the state of the push buttons and the number of pushes Prog12.dl8
Fig. 23.
6.9
Flexible Tongue (Labelled 2BGI, 8C(LT) 5*V)
The SSP has a flexible tongue along the front edge, which has fine copper tracks on both the topside
and underside of the tongue that are configured as two active arms of a bridge.
The strain on the tongue as the tongue is depressed can be read by the program. Prog13.dl8
Fig. 24.
The strain will increase from approximately 3500 to 3540 PPM as the tongue is fully depressed. The
strain on the tongue can be zeroed or tared as follows Prog14.dl8
Fig. 25.
The tongue also has a coil (in blue block) on its free end, immediately adjacent to a fixed coil (also in
blue block). When the coil on the tongue is energised, its magnetic field influences the fixed coil. If the
tongue is depressed then released smartly so that it vibrates, then these coils can be used as a
magnetic pickup to measure the vibration either as:
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