Hacking the Fluke 117 DMM - Page 1
Forum section: electronics / testgear

author: ZGoode
author_rank: Frequent Contributor
timestamp: November 05, 2024, 03:30:40 pm
content: Has anyone trying hacking the Fluke 117 or similar models (115) to talk to it from a PC or separate MCU? I am trying to add UART so I can add logging to an Arduino on mine but am not having any luck so far. When I was probing around to figure out pinouts, it appears that the 4 pin (P2) breakout connector on the side next to the main chip is connected to the battery and default UART pins on the TI MCU, but it seems Fluke used one of those pins for the backlight mosfets (annoying since they had a 100 pin chip so a lot of I/O), since when I put 3V/0V on that pin the backlight toggles.My plan was to do something similar to what Spritesmods did to his Fluke 15 here,https://spritesmods.com/?art=fluke15pluswifiAny feedback or suggestions here? I was hoping that Fluke had left some pins broken out for development debugging, but so far no luck. the six pin holes above the 4 I discussed previously appear to be for JTAG (or whatever the equivalent is with the MSP430), and I have not messed with those yet since I do not have any tools for working with TI MSP430 stuff.

author: coromonadalix
author_rank: Super Contributor
timestamp: November 05, 2024, 05:44:48 pm
content: a 430 jtag interface doesn't cost a fortunei would check the 6 in line pins near p2 to see where they go on the 430 vs the datasheet

author: BTO
author_rank: Frequent Contributor
timestamp: November 05, 2024, 05:55:11 pm
content: Quote from: ZGoode on November 05, 2024, 03:30:40 pmHow are you mate,1. This looks interesting2. I also have a Fluke 1173. If it helps i have a JTAGulator4. I see what you're trying to do , You basically want the 117 to be a network device and interface with the P.C. via Arduino so you can get measurement datafrom itMy first advice would be , USE .E.S.P. 32 Not arduino.The article did Mention 8266, Go with ESP32, it's a lot better, You can do anything on ESP32 that you can on Arduino, but not the reverse.Also ESP32 is already setup with network capabilities INCLUDING WIFIYou could integrate the WiFi Functionality of ESP32 to connect to your PC via your routerYou could use the internal pins of the ESP32 to communicate with the 117then.. You could use other pins on the ESP32 to communicate with the Screenit's basically setup for you, we'd just have to write the code for it.Also i'm happy to work with you on this together if you like.Also Re the backlight, i also think it's shit when the backlight turns off, you need to turn the meter off and on again to get it to wake up.I wouldn't mind having a fiddle with the 117Speak soon

author: cc
author_rank: Newbie
timestamp: November 06, 2024, 07:26:24 pm
content: Sadly I don't have a fluke MM so I can't give advise on how to implement it, but I have done something similar with my ut-61e+ using an ESP32-S3BTO gave some solid advice in regards to the ESP32 over an arduino. You don't have to give up the arduino framework (or even the IDE though I could go on a 50 page rant about it, I'm a vscode+pio fanboy) so most boilerplate code is infact compatible with an ESP32I recommend an ESP32-C6 or C3. Both run on the risk-v architecture which has insanely low power consumption, both are also single core which is better for battery (unless you require a second core for something other than your data logging function?). The C6 also has BLE 5.3 (C3 has BLE5) which reduces power consumption a tiny bit more, but it's negligible, both are good choices.In terms of processing power, all three are overkill TBH, it's all about choosing the lowest power consumption imho when it comes to datalogging in 2024Oh, look to use BLE instead of wifi. Wifi is great if you want to view your live data on your phone from abroad, but you'll likely be next to the multimeter when you're logging, right? If you do want "wireless viewing", BLE is far more power efficient than wifi for waking/sleeping/even idle consumption. What I'd do is have a master ESP32 plugged in with wifi enabled & put a slave in the the fluke 117, send the data from the fluke to the master esp32 and let that one do the heavy lifting.I have to go eat but I wanted to post the power consumption comparisons / calculate how many hours out of the MM battery when logging you should get. I will prolly do it latergood luck with the project!oh ps. I just thought, go on github/gitlab and search for your MM's name.somebody may have done it before, just not documented it on a blog/yt video so google doesn't come up with it. at the very least you can search for the ut61e, which has a bunch of datalogging mods based on the esp32. it should save a lot of programming time as the code should work on the fluke/be fairly universal once you've figured out the io & changed the gpio pins if they use the arduino frameworkedit: just remembered, the C6 has zigbee & thread(?) radios. not sure of the bandwidth, if it'd be enough, nor do I know if theyre better for battery... that's something to research. may be better protocols than even ble. speaking of BW, ble averages at 90KBps afair, which is far more than enough for your average MM datalogging 2-6/sec sample rate.

author: ZGoode
author_rank: Frequent Contributor
timestamp: November 06, 2024, 07:39:11 pm
content: I should clarify, when I said "Arduino" I was using that term generically. For ease of testing it is what I am looking to use in the short term, but my end goal is to use the NRF52805 with ANT+ or similar. I'm fairly familiar with the ESP32 ecosystem, but in this case I am thinking Nordic Semi parts might be better here since they are really good at low power wireless from what I have seen.In the meantime does anyone have a particular JTAG debugger they recommend? I have Atmel/Microchip stuff already as well as a JLink, of which neither will work with MSP430 from what I have seen. I also have a Xeltek 6100 Superpro which I know can program these chips, but I doubt can be used as a debugger.Unfortunately, I need to temporarily put all my work on hold since my computer killed itself yesterday and I am waiting for Lenovo to figure it out (GPU memory most likely).

author: Fungus
author_rank: Super Contributor
timestamp: November 06, 2024, 07:57:37 pm
content: Quote from: BTO on November 05, 2024, 05:55:11 pmI don't want to start a religious war on here but facts is facts and that is simply NOT true.

author: BTO
author_rank: Frequent Contributor
timestamp: November 07, 2024, 10:15:28 am
content: Quote from: Fungus on November 06, 2024, 07:57:37 pmQuote...............IT'S ON !!!!

author: BTO
author_rank: Frequent Contributor
timestamp: November 07, 2024, 10:17:13 am
content: Quote from: Fungus on November 06, 2024, 07:57:37 pmBut seriously though.... Why do you say that ?Also let's not make this a big thing and get off the main topicBUT.. HIS COMPUTER IS BROKEN ANYWAY.. WE have a day or two :p

author: BTO
author_rank: Frequent Contributor
timestamp: November 07, 2024, 10:20:49 am
content: Quote from: ZGoode on November 06, 2024, 07:39:11 pmQuoteJTAGULATOR , Not cheap, but really goodhttps://www.ebay.com.au/itm/285932986040?chn=ps&_ul=AU&google_free_listing_action=view_itemShameless promotion LOL

author: squadchannel
author_rank: Frequent Contributor
timestamp: November 07, 2024, 11:02:18 am
content: from the trace, the P2 appears to be USART.there maybe similar models that are PC communicable. command list may be close.

author: ZGoode
author_rank: Frequent Contributor
timestamp: November 07, 2024, 02:30:14 pm
content: Quote from: squadchannel on November 07, 2024, 11:02:18 amThat was my first thought too. But one of the pins on P2 is ground, another is battery +, another appears to be the backlight mosfet control, and the last one I have not determined yet. Although my meter could just be behaving weird.

author: Everett_Tom
author_rank: Contributor
timestamp: December 16, 2024, 03:38:12 pm
content: P2 is a serial port, but it's not "safe" to use when the DMM is measuring; there isn't any isolation between the ground and the DMM input ground. SO - any high voltage you means may end up on that port - not great for a PC or a non-isolated serial connection. I saw somewhere a setup where a board used the Batt and Gnd to power an optocoupler, and the other two pins are RX and TX—using commands like the "ID/r" or "QM/r." I think the backlight mosfet is for the FCTY mode ( unit off -> hold the "HOLD" button, and then switch the knob unit you see "FCTY", release the knob - you'll see the backlight flicker as it sends data out". That probably means that the line you have with the mosfet is the TX line.

author: ZGoode
author_rank: Frequent Contributor
timestamp: December 17, 2024, 03:29:10 pm
content: That makes sense. I tried sending commands over the pin not connected to the backlight MosFET using a variety of different USART settings at 3V (since that is what the MCU appears to be running at), but had no luck in getting any kind of response. Any chance you are able to find the link to where you saw that?FWIW I was planning on adding a wireless module here to keep the isolation, definitely don't want to fry my PC. I wasn't planning on doing any live measurements without any kind of isolation, both for my safety and my equipment's safety.

author: Everett_Tom
author_rank: Contributor
timestamp: December 18, 2024, 06:10:36 am
content: I don't remember, sorry, it's been awhile. You might be able to go into the "FCTY" mode and see if you can get data off the RX pin - if they are the same line. That might give you a hint on serial port settings.I think I have a Fluke 115 somewhere, and I'm sure I also have one of those FTDI serial pins to USB cables. I'll try with mine over the break if I get a chance.