This wire is the TDM data signal being transmitted from the multiplexer to the demultiplexer.Ĭonnect all other multiplexer and demultiplexer enable inputs to constant values corresponding to their active levels (to enable these modules).Ĭonnect the ENABLE inputs (ENABLE P, ENABLE T) to their active levels (logic 1) to enable counting, and connect the LOAD and CLEAR inputs to their inactive levels (logic 1) to disable the corresponding functions.Ĭonnect the counter parallel inputs D-C-B-A to logic 0. Pulses on the CLOCK will increment the counter, thereby selecting channels in sequential order.Ĭonnect multiplexer output Y to demultiplexer enable signal G2A. Connect the 8 th multiplexer input to logic 0.Ĭonnect the 8 th Digital Writer output to the CLOCK input of the binary counter.
To supply the data to be transmitted, insert a Digital Writer into the circuit and connect its first 7 outputs to multiplexer inputs D0-D6.
(In the actual experiment, these will be connected to LED0-LED7 on the ELVIS workstation.) (The fourth counter output, QD, will be left unconnected.)Ĭonnect the 8 demultiplexer outputs to probes and/or a Digital Reader to display the data on the 8 “channels”. As the counter increments, successive channels should be selected. Use Multisim to create a schematic diagram of an 8-channel TDM communication system with the 74LS151 as the multiplexer, the 74LS138 as the demultiplexer, and a 74LS161 binary counter (similar to the counter used in Experiment 2) as the channel selector.Ĭonnect counter outputs QC-QB-QA to the C-B-A selection inputs of the multiplexer and demultiplexer, so that the counter “selects” a channel for transmitting/receiving data.
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