Video Blog 176 - HP3478A Multimeter Repair & TFT Conversion

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Published: Sunday, 15 February 2026

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DISCLAIMER: This video is educational only, so if you decide to do the same yourself then you are on your own, I can't be held responsible for any problems/issues/damage/injury that may occur if you decide to follow this blog and try it yourself.

VIDEO BLOG

Off the back of my recent HP3457A TFT conversion I was asked if it was possible to carry out a TFT conversion on it. So, I have one to hand but it needs repaired first!

The PCB gerbers, BOM, HEX file, 3D gcode/stl & instructions - https://www.ianjohnston.com/misc/3478A_TFT.zip
Where it all started - https://www.eevblog.com/forum/projects/led-display-for-hp-3457a-multimeter-i-did-it-)/
XI's Protocol post - https://www.eevblog.com/forum/projects/led-display-for-hp-3457a-multimeter-i-did-it-)/msg1347268/#msg1347268
GIT source - https://github.com/Ian-Johnston/3478A_VS_Display

YouTube Video:

Programming the BluePill board:

Use an STLink V2 or V3 programmer, clone's should work.

Leave the Boot0 & Boot1 headers as default.

The following can be done with the BluePill in-place and my Pcb connected to the meter,
otherwise you will need +5v power to the BluePill board if doing standalone.

Connect using the SWD connector (the USB connector is not used):
SWDIO -> SWDIO
SWCLK -> SWCLK
GND -> GND
3.3V -> 3.3V (VREF)
NRST -> NRST

Method 1:
Open STM32 ST-LINK Utility
Target -> Connect
File -> Open File
Select .hex file
Target -> Program & Verify
Click Start

Method 2:
Open STM32CubeProgrammer
Select:
ST-LINK
Port = SWD
Click Connect
Open File
Select .hex file
Click Download