Alexander Huemer's FPGA Adapter Board Brings HP 54520C/54540C Oscilloscopes Back From the Dead

Sep 21, 2023

Electronics engineer Alexander Huemer has designed a must-have accessory for anyone working with Hewlett-Packard 54520C or 54540C oscilloscopes — adding a VGA output to provide a large-scale mirror of the display on an external monitor.

"The HP 54520C/54540C series of oscilloscopes is equipped with color LCD displays, in contrast to their non-C predecessors which had monochrome CRT displays," Huemer explains. "While the multi-color display is nice in principle, the LCDs that were used unfortunately commonly failed. Those scopes are still quite capable by 2023 standards, hence worth preserving."

Rather than trying to find a compatible display, though, Huemer opted to build an adapter — taking the proprietary signal from the oscilloscope's mainboard and converting it for use with any display capable of accepting a VGA input, including compact LCDs that can fit within the stock oscilloscope housing or large-format external displays.

The signal conversion comes courtesy of a TinyVision.ai UPduino, a compact breadboard-friendly field-programmable gate array (FPGA) development board built around the Lattice UltraPlus ICE40UP5K chip. This is mounted on a custom PCB, which is designed to attach to a display using the VESA mounting points — and that includes two mirrored VGA outputs, one for an internal monitor and one for an external monitor.

Those looking to add a large-format external display to their 'scope, however, should be aware of a particular HP design choice and its impact: "HP decided to mount the LCD panel upside down," Huemer explains. "Probably as that was convenient is regards to the position of the connectors. An implication of that is that the internal VGA monitor is mounted upside down as well (which doesn't make a difference really) and that an external monitor must be rotated as well. If one would desire to change that, a frame buffer must be implemented in the FPGA, which isn't hard to do but required more RAM than the UPduino has."

The design files for the project, which was inspired by earlier work on a conversion board by Adil Malik, are available on GitHub under the CERN Open Hardware License Permissive 2.0.