Tektronix DPO front panel as a poor man's DPO7AFP - Page 1
Forum section: electronics / testgear

author: tmbinc
author_rank: Frequent Contributor
timestamp: September 14, 2025, 09:24:31 pm
content: I'm a long time DPO5034 user (see e.g. my slightly bitrotten teardown athttps://debugmo.de/2013/03/whats-inside-tektronix-dpo5034/- wut, that was 13 years ago?), but what always bugged me - SINCE 13 YEARS - were Tektronix' abysmal UI choices specifically for the DPO5000 series. The other ones were fine (DPO4000 has the simplified UI that matches the buttons; DPO7000 has the larger frontpanel that matches the UI; but DPO5000 has this weird mix of 7000-series UI and 4000-series buttons, that constantly requires you to use on-screen menus for simple things like changing the trigger source).At one point I got sufficiently annoyed that I hand-assembled .net bytecode into their DLLs to have some shortcuts, but the next scope software update reverted it and I got tired of it.I always dreamed of the weird "DPO7AFP", the "auxillary frontpanel" that Tek sells for their "ATI" low-profile series of oscilloscopes that don't have a front panel, but it has a list price of 5k and I never found a used one.Finally, a month ago on ebay, a few used DPO7000 front panels showed up for as little as 40 EUR (complete) and 20 EUR (with missing knobs). I bought one, and it smelled like it had survived a fire, but I was able to clean it.Looking at the PCB, it's essentially a Cypress FX1 (USB full speed microcontroller) and an Altera FPGA that drives all LEDs and buttons. So yay! It has USB - can I just plug it in?Tracing power a bit we arrived at the conclusion that it needs 3.3V (not 5V) for both the MCU, FPGA and LED voltages.I apologize for not having this documented better, but the pinout should be something like:GND 10 9 USB D_PUSB D_M 8 7 GND6 5 VINVIN 4 3 GND2 1 VIN_LEDAgain, VIN is 3.3V _not_ 5V! (For VIN_LED I'm not sure, it's a separate input, but the LEDs seem to work fine and have the right brightness with 3.3V; though some colors look a bit off.)Powered, it now enumerates with the FX1 bootloader. I tried to find the right bits for the firmware for a while and it was surprisingly hard. But eventually, I just plugged it into my DPO5000, let it search for the right USB driver, and - it found them! Apparently the DPO5000 firmware just includes the DPO7000-specific bits (where I assume this is just on the USB bus?). I think it's "tekfploader.*" and "tekfpusb.*", and their .inf files reference fpfw.hex (FX1 firmware) and fpio.rbf (for the bitstream).I also sniffed the initialization sequence, if someone wants to build this into an open-source tool, but I failed to properly re-enumerate the FX1 after uploading the firmware.But the best is that the DPO5000 firmware just supports the frontpanel - if you keep it plugged it when starting TekScope.exe, it will even adjust the UI slightly (so now the device frontpanel acts weirdly) to match the frontpanel.Looking at the DPO7AFP, I think what I built is probably _exactly_ the DPO7AFP - which is just the DPO7000 frontpanel with some plastic and a 3.3V regulator.And using the oscilloscope is so much more fun now. The selection of the trigger channel with the frontpanel alone is so simple, but a game-changer. The only downside is that there's no "BUS" button anymore but I can live fine with having to use the menu for it. It also works nicely if you RDP (or VNC) into the scope.

author: TinLethax
author_rank: Regular Contributor
timestamp: September 15, 2025, 12:29:08 am
content: Love those convenience Arm Ready and Trig'd LED indicators. Wish my scope can have them too.Can you try installing USBPcap on your scope and capturing the USB traffic?If we can reverse engineer this then we can grab a Pi pico w, write a USB firmware for it (Tek is probably using vendor defined USB class, but it can be HID too). Then run a WiFi and host a local web based front panel.

author: tmbinc
author_rank: Frequent Contributor
timestamp: September 17, 2025, 04:55:25 pm
content: Didn't USBpcap it, but used a hardware sniffer, see the attached dump.

author: rvalente
author_rank: Frequent Contributor
timestamp: September 17, 2025, 06:26:03 pm
content: The very first time I saw the DPO7AFP I thought "what a nice idea" this kind of accessory should be adopted by Siglent, Rigol and others, a neat little USB device (similar to a MIDI table) to work with all scopes. No more channel selecting because they share the same vertical knob or a little device on the bench to save precious bench space!

author: TinLethax
author_rank: Regular Contributor
timestamp: September 18, 2025, 12:09:19 am
content: Quote from: tmbinc on September 17, 2025, 04:55:25 pmIt seems like the firmware was loaded over USB. Quite similar to the FX2LA logic analyzer, just some small bootloader and the application was loaded via USB Bulk transfer.

author: tmbinc
author_rank: Frequent Contributor
timestamp: September 18, 2025, 10:07:02 am
content: It's a Cypress FX1, so yes, the 8051 firmware is loaded over USB. However, I couldn't get the firmware to re-enumerate.The bulk transfer is the FPGA bitstream for the Altera FPGA, which I think is essentially a port expander and PWM driver.But I like the idea with using an RP2040 or similar to make this wireless.