Parallel bus - introduction

Parallel bus usage in electronic design was widespread in high-speed applications throughout the 90s making it possible to transmit significantly more data between devices in comparison to serial buses. Today, even though serial buses (because of their lower cost and smaller footprint) are the current preferred form of device communication, parallel bus usage has seen somewhat of a resurgence. Parallel buses are currently being used in applications such as FPGA programming, flash memory pen drives, and RF communications to transfer large amounts of data quickly.

Parallel bus communication transmits multiple bits of data simultaneously sampled at the speed defined by an additional clock line, and within the defined edges of an optional chip select line.

Serial Decoding Parallel Interface

Image from Wikipedia

Wiring

Parallel bus communications utilize up to eight data lines driven by a clock line, and can also include an optional chip select line. The eight data lines are identified as D0, D1, D2all the way up to D7. The D0 line is recognized as the least significant bit (LSB) and D7 is the most significant bit (MSB).

Capturing and analyzing parallel bus communications with PicoScope

To decode Parallel bus waveforms using PicoScope 7, select Serial decoding from the More tools menu to launch the serial decoding dialog.

Serial Decoding Parallel bus decode

Next, select Parallel bus from the list of available protocols.

Serial Decoding list PicoScope

Select the corresponding PicoScope input channels for Data (up to 8 Data inputs), Clock and optional Chip Select lines within the Configuration tab.

Serial Decoding PicoScope

In the Display tab, select the desired Graph and Table display format options to display Parallel packets in the appropriate locations. 

Serial Decoding PicoScope parallel

Double-click a packet in the graph view to see the same packet in the table view, and vice versa or use the zoom feature to focus in on the appropriate areas of the decoder packets.

Serial Decoding PicoScope