OK making Bluetooth SPP work on Linux ils a bit tricky, but it werk! Note the comm port is rfcomm0 in there. I guess I need some udev black magic to make it "just work™" but ok

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Breadboards are wonderful tools that let you very easily spend 2 hours chasing your tail by just swapping 2 wires... Anyway, progress, after the stm32 (f303k8), I have now the AR488 code github.com/Twilight-Logic/AR48 running on an esp32 (via SN75160/161 transceivers). Now let's see how to make this GPIB "dongle" wireless...

I finally got this project more or less finished! The USBDevice support for the STM32F303 has been added very recently (but a PR is still waiting to be merged), so I could finish the project!

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But no worries, the 20+ years old microwave oven is back, ready for duty. Was not its first surgery. But so far so good.

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Hopefully this replacement oil filter for the lada engine in my old fork lift wont' leak as badly as the original cracked (and impossible to find) part

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Allow me to tell a thing: dismantling a car ECU (need a new pressure sensor) is a pain in the wu-ha... The thermal glue used in there makes it **very** hard to pull the PCB out of the aluminum casting enclosure...

The ref voltage is a bit off (6.0v) but well within the required range (+/-0.3v). After a quick adjustment, it's starting to look better

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But it was pretty unstable, mainly because the 2DW233 was drived too low with current schematic: at 1.5 mA instead of the expected 7.5mA (for the 233). So I played a bit with ltspice to find better values for R61 and R63, and I also replaced the opamp with a 741 I found while cleaning a bit my bench :-)

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So here is current situation: the 5.9v zener reference has been replaced by a 2DW233. First quick check was a bit dodgy: this ref is normally 6.2v, but actually consists In 2 zener head to head, so in practice a 5.5-ish v zener in series with a forward one (so .6-ish v). So I've used only one of the zener of the 2DW233 in series with a germanium diode. I also used a random opamp I had but had not the correct pinout (it's a dual opamp). The result is a bit dodgy as I said, but it worked: 5.87v

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Yes, this poor little optocoupler is not straight, but it does work. Now I have decent voltage readings (here fed with 0.5v)

But it was still not working. After fighting with the poor quality (but available) schematics from the service manual still available on Keysight web page, I could identify the culprit: one of the optocouplers was dead (on the LED side). Funny enough, it is listed as a TIL111, but it's a 8-DIP package (the til111 is a 6-DIP). So I had to improvise...

After replacing it with what I had, a simple 6.2V zener and replacing the opamp with a random one (but with matching pinout), I finally got the voltages in the correct ballpark.

Then I checked the power supplies, and sure enought, voltages on the inguard board were completely wrong. Turned out the 5.9v reference voltage zener is cooked, as well as the opamp driving it. This 8 pins can is actually a zener diode (obviously made of unobtainium)

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