All in all, I feel like I have succesfully diversified my multimeter assortment. I have a Fluke 17B I can use for daily work so I can enjoy quick continuity testing and non-irritating power-off features, and I have the 15B+ as a very capable second multimeter, with WiFi connectivity to show trends and to allow for any device with a browser to act as a remote display. It's a shame I couldn't figure out more of the way the main multimeter chip works to get direct access to the display, but the PWM-trick I did to show the IP-address is an alternative that is workable. Here's a demonstration. As you can see, the multimeter has the IP of, and that's what I enter into the browser.

As usual, all the code is available for download by doing a git clone on http://git.spritesserver.nl/fluke15bpluswifi.git/. Because esphttpd already was licensed as such, the rest of the code is also licensed under the Beer-Ware license. If you manage to do anything interesting with it, as usual, I'd appreciate a message, I always like to read about what interesting ideas others have. If you want to do anything yourself with the serial protocol, I'd also advise you to take a look in the source code: the fluke15bplus.c gives a fairly thorough description of the protocol details. One last word of warning: if you send something over the calibration port that messes up your multimeters calibration, I'm not responsible. Please do not make any life-or-death decisions with a multimeter that's been messed with, but otherwise: have fun!

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Paul wrote at 12 Jul 2022, 9.52:

Excellent work!

Daniel wrote at 21 Aug 2019, 5.45:

Great work man, unbelievable!!

Pete wrote at 16 Sep 2017, 4.39:

This is very neat, thanks for sharing. The cap that hooks to the 10A input... from the schematic, I assume it's only connected to the board at one side, but in your photo it looks like it's bridging the same two pads that R22 connects. Is one side just "floating" above the pad? And if I were to try to replicate this hack (thinking about it for my 17B+) is there a reason the cap is there instead of by the ESP? And, not really a question about your hack, but the multimeter circuit itself. Is that big wire loop at R22 really a resistor? It looks like just a huge bent wire. I'm curious what purpose it serves, if you know.

jkutianski wrote at 17 Jul 2017, 15.04:

The link for the FS98O24 is this http://www.ic-fortune.com/upload/download/fs98o24-ds-10_en.pdf

jovan wrote at 12 Jul 2016, 19.46:

Great hack, you should have just fixed ip adress for esp8266 mac address, but anyway, liked idea of displaying ip on multimeter ;)

Mike wrote at 5 Jul 2016, 5.38:

Kuddos, great hack Sprite_TM! We are some guys who have been working on a multimeter optimized for hacking, and would love to give you one to play with for free when it will be ready in ~6 months time. just give me a shout at mbl at voltset dot com :)

Amos wrote at 7 Jun 2016, 23.33:

@Dave: The serial port is in the meter. He only mentioned the EEPROM because he removed it to prevent anything he sent over the serial port from overwriting the calibration values stored in it.

Dave wrote at 7 Jun 2016, 19.22:

I am really confused. If the EEPROM used I2C how did you ever connect to it using standard 8bit NRZ data? like you said.

some guy wrote at 7 Jun 2016, 15.54:

excellent work (as usual from you...), just some minor problem: the link FS98O24 is broken

Mike Szczys wrote at 7 Jun 2016, 15.45:

Spectacular hack as always Sprite_TM! I especially enjoyed working my way through the circuit that lets you power up/down the ESP12 with the HOLD button.

Claude wrote at 7 Jun 2016, 13.21:

Nice one Sprite_tm ! I might pop open my Fluke 110 :)

Leenix wrote at 7 Jun 2016, 12.07:

First off, amazing hack. Have you thought of running an mDNS server on the ESP chip to get around the IP issue? There's libraries for an Arduino implementation already (https://github.com/esp8266/Arduino/tree/master/libraries/ESP8266mDNS). That way you could just go to a "*.local" domain if you're on the same local network and the ESP would resolve your address.

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