STM32 powered multimeter

I read on EEVBlog that Dave is creating his own multimeter together with a company. He’s already using prototypes in his videos, one of the last replies in the thread he said the following about the hardware:
STM32L152D
Schematic and protocols will be open, not sure about firmware.
Standard low cost ST ARM programmer header.

could become a fun device to hack XD (and it’ll also have an esp8266 in there for bluetooth connectivity)

http://www.eevblog.com/forum/chat/new-e … msg1137968

Looks like a fun project. If it uses a 50,000 count DMM chip it will also be genuinely useful rather than just a fun thing to hack. Does this mean I will have an excuse to buy yet another multimeter. I’ll need to do a DMM head count and figure out how many I already have. I suspect the number is bordering on the mildly obsessional already. One more might push me in to “requires psychiatric advice” territory.

EDIT: OK I’m sure I can fit in at least one more… I only have..
1 x Uni-T 61E – with manufacturers opto-isolated serial and home opto-isolated made USB serial dongles.
2 x Victor VC921 – hacked by my alter ego “itsthatidiotagain” for opto-isolated serial. => https://www.eevblog.com/forum/testgear/ … or-vc-921/ and for 8000 counts.
2 x DT-830B – genuine exploding 2000 count “Chinese fire cracker” multimeters (yellow)
1 x DT-830B – ditto but in blue.
1 x Uni-T “Logic analyser” 2000 count circa 1995?
1 x Victor “Pocket multimeter” origin unknown.
2 x Draper brand Fortune semiconductor based multimeters.
1 x Fluke 17b (in the office)
.. and no doubt a couple of others …

I think the simplest way to get +/- 32000 counts is with ADS1100 – 6pin complete acquisition system.
Works great (mind it has got a fixed i2c address so in case you need several on a single i2c bus you must order chips with different addresses).
I’ve tried as a high-side current meter with success.
There are other ADS1xxx as well.

I wonder if this is the project that Dave bought the STM32L4 discovery board for.

Dave did a video about the STM32L4 several months ago, and I can see that the discovery board would be an ideal testbed for this, as it has a large monochrome LCD display.

Part from the someone else ripping off Daves design and producing it more cheaply, I think he would be better off making the firmware open source, on github as it would save him a fortune in dev costs if he just published basic functionality and the community is likely to write loads of enhancements.

Daves multimeter is now on kickstarter:
https://www.kickstarter.com/projects/ee … ultimeter/

i’m really considering getting this
fully open hardware design
stm32 based, with st link header available, but also firmware updatable via micro sd card
and probably just a great multimeter for what we do
and a lot of connectivity options

OT
on the web while hoping from sites to sites, i stumbled into one of these
https://www.eevblog.com/forum/testgear/ … eo-review/
they are rather cheap
https://www.ebay.com/sch/i.html?_nkw=an8002&_sacat=0
and i picked up one from a local web market/store doing a promotion, it is shipped from china though
——–
back on topic, i think the idea of having bluetooth and logging in a multimeter is a rather useful feature perhaps
though for most of the times, i simply use the little multimeter as a beeper to check connectivity / shorts and basically to measure voltages / resistance

Unless I am miss-reading the kickstarter page, the cost if the meter appears to over $250 AUD, ( probably around $175 USD) !!

Its definitely well out of my price bracket

[RogerClark – Tue Dec 05, 2017 8:16 pm] –
Unless I am miss-reading the kickstarter page, the cost if the meter appears to over $250 AUD, ( probably around $175 USD) !!

Its definitely well out of my price bracket

it’s indeed not cheap >_<
and it’s more like 200$… pretty high end meter

I paid the same for the Metex M-3850 (long time back..) thus it is not expensive

Its a strange world.

People buy BluePill boards with defective USB as they wont pay an extra dollar for a maple mini.

But people will spend $200 on a multimeter, and then only use $10 worth of its features and capabilities.

Edit.

i dont think these two groups of people will actually overlap.

I suspect anyone who wants save $1 and solder a resistor to a BluePill, is not likely to then go out and spend $200 on a multimeter

[RogerClark – Tue Dec 05, 2017 8:34 pm] –
Its a strange world.

People buy BluePill boards with defective USB as they wont pay an extra dollar for a maple mini.

But people will spend $200 on a multimeter, and then only use $10 worth of its features and capabilities.

true XD

Do you mean they will do measurements with 2500 counts only?

the simplest way to get +/- 32000 counts is with ADS1100

I’m a big fan, for adc, of F350 from Silabs. 24bit adc, and PGA. the only catch there is your choice of oscillator to minimize jitter.

actually stm32f103 with 12 bits adc, my guess is that it is literally pretty accurate as 2^12 = 4096
i’m not too sure how that’d translate to counts though and i’m wondering if we use both adc on stm32f103 would there be possibility of getting higher precision?

actually stm32f103 with 12 bits adc, my guess is that it is literally pretty accurate as 2^12 = 4096

for a noise free measurement, a 12bit adc may deliver 10bit, and likely 9.x bits. Plus, the inability to use dual reference in makes it harder.