Multiplexing a Bitstream

Multiplexing a Bitstream

Signal Conditioning Technique

This technique can be used in any GreenPAK.

GreenPAKs are often used to transfer a data pattern. If the data is transferred from the GreenPAK or the data is transmitted along several lines from the SoC, they must be amalgamated for transmission on one line. Below is an example of the GreenPAK multiplexing a bitstream originating from the ASM output RAM.

The generator circuit is shown below. The generator implements the operation of the CLK line for the synchronous data transmission, enabled by the EN signal. The generator also implements the multiplexer operation algorithm for the correct combination of the transmitted data on one line.

The 8-bit Multiplexer circuit is shown above. All LUTs are configured collectively as the 8-bit multiplexer (see AN-1003). The MUX Truth Table is shown in above. The multiplexer outputs the combination of bits from the ASM block outputs according to the algorithm of the generator and the data is transmitted on one line to DATA. The DATA output will always be the same as the MSB of the ASM output RAM. when EN is LOW. The ASM output RAM can be changed via I2C. Logic can also be implemented to change the state of the ASM in order to change the data bits. If the ASM isn’t available, the inputs can be pulled high or low for the data values.

Resources

GreenPAK Designer files