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Andy

Mon Feb 03 2014, 10:51PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

I'm planning on making a tablet with a multimeter and oscilloscope built in, found that mucking around with electronics without testing tools you don't get there far. The tablet will have a basic OS with the software doing the heavy lifting.

I've order a PicKit3 to program picmx110f016b which is a 32bit PicMicro with a 10bit analog to digital converter. I've allready got the pics.
Drawing up a test multimeter circuit, about to send it away to this crowd

it should be $85nz for one, this is just for experiments and to get the programing sused.
Parts on hand 10 hex inverters, 6 mosfets IRF540N, will have to order some caps and resistors.
Have to get a LCD screen to display the results, witch should plug into the circuit.

This is going to be a slow project.

Andy

Mon Feb 03 2014, 10:51PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

This is going to be the layout.
At the top there is a magnetic and electric field sensor for input, which will supply input for the current data, picking up signal radiated by the antennas, to detect maybe underground cables, measure voltage from a stand off, or what ever function software wants to do with the input.
Below that is the multimeter and scope, which I'll work on first, it will have voltage,frequency,wave form,inductance and capacitance, it will be able to get data from the rf module.
To the left is a high voltage source connected to the B&E sensor, for some reason from software.
The CPUs linkup the different modules, and run a OS.
To the right is the network module, things like ethernet/wifi/zigbee, with protocols for decoding etc for the cpu.
The bottom module high frequency, does all the well I don't know...

This is level 1, top level out of three, this has the multimeter and the B&E sensors. This has a couple of resonance filters, three cap phase shift for more accuracy, a cap and inductor series/parallel for finding out the sizes for caps and inductors. It has a group of inductors for detecting magnetic fields,and a electric field part. A voltage range of 30small steps and a total of 120volt.Added two ad converters at 16bit, they have a high frequency filter connected to one Pic which is connected to another with a slower(wider bandwidth), for Fourier wave in wave functions. I've got some room on this board, if anyone has a suggestion of what I can add, that as high voltage, I'm all hears.

file

x
Edit, added noise cancellation , and another two efield sensors, place software frequency select(the transformers top right), the bottom Pic has connections display.

Gerber file

]gerber.zip[/file]
If you are going to use the gerber file, you might want to check that all holes are there, and the clerances, when the test PCB arrives, will find out weather the design could work

Level one should be done, when the test PCB arrives, will start coding, I'm trying to make it so the hardware kitchen sink is in there and the software from the OS mixes and matches different parts to make some function, Looking into running code from RAM, each Pic will have small functions that code from RAM combines.

The 2 level is the CPUs/network breakout boards and the battery. The 3 level is the high frequency generator and signal processing.

Version two of the multimeter, replace the other Pic with this one

Its giving more space on the board and has a fast clock speed, the V3 will probable have more cap/inductor parts to select a large distance range when used with the e-senses.

This should be the final version, added vias on the top/bottom connection and just a couple of changes, the Pic on the far right will be connected to LCD for tests, but the CPU for the final thing.
Theres just one thing about the design I'm unsure, it say in the manuals that the MCLR line should have a cap on it because of the frequency it operates at, but most of the other Pic range does, you might want to check if you use it like this.

]gerber.zip[/file]

Andy

Mon Feb 03 2014, 10:52PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

Source

Will update as I go along and learn some, this should sample once, the code at the top of the for loop, checks the value of the hex inverter lines, to work out multiples of 3.5volt(3.5/7/10.5/14v), grabs a sample, then stores it to compare against a peak value, which will get passed to a LCD, it will also workout the waveforms, how long it stayed at the peak, before getting close to zero(0.5%+-), and from peak to zero back to peak, and workout from the timing of code what the frequency is)

Will post the code in zip files, incremental , it pretty basic at the moment, the idea is make it the CPU level sends commands to the level1 section which allows the device to be programed at run time, to make it easily hackable, it will have a hardcoded program which it can fall back to.

Revsion 3, I've manged to slow a 200mhz chip down to about 1mhz

, I'v still got to write high level functions, which should allow the speed to go back up, has a basic program of what it should be like.

]level1.zip[/file]

Revsion 2,Cleaned it up, it now has mov/lea/adc/add/and/or/sub/mul/div/xor
Needs jump table at the start to speed up jumping to the right opcode.
RV2.0

]level1.zip[/file]

Andy

Mon Feb 03 2014, 10:54PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

Multimeter
Parts
2 hexinverters

6 Mosfets IRF540N(80volt)

7 1Mohm resistor

2 0.1uF caps

1 LCD

1 voltage reference

1 28pin socket

1 10kohm resistor

Dimensions 105mm*85mm
1 470ohm resistor

3 diodes

The above one won't work with dc. Just for testing to get the programing sorted.
Extra parts
Mosfet driver

Voltage reg 3.3volt 500mA

Inductors

AD converter

Capactors

Andy

Mon Feb 03 2014, 10:54PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

The Pickit 3 arrived, unlike the Pickit 2 can't replace the chip and reprogram another chip, and my test board has got the interface for that as well, at least will see how well Eagle to PCB turns out, and if the schematics above will come out right.
Ordered the screen, will test it on the demo board from the kit(PIC18f45k20), It has a adc and enough ports for a parallel setup, should beadle to test the screen in 6 days.

They did a good job of the PCB, sent two for $120, I think I stuffed up on selecting the size of the Pic thought. Should be all good to send a larger schematic away when finished.

The TFT display arrived, putting it in storage, will be taking a break from this project for a couple of months, to get my business setup.

Andy

Mon Feb 03 2014, 10:54PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

Shrad

Tue Feb 04 2014, 06:52AM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
Location:
Posts: 780

I have an explorer16 board with pic32MX360 and pic 24fj PIMs for sale, please PM me is interested

integrated pic18F4550 has been flashed with pickit2 firmware and is programming and debugging all the supported devices of pickit2

all you have to do for LCD support is either add a graphical extension, or exploit the existing connection

what I'd do is use a standard serial programmed LCD panel with built in controller and serial touchpad though

please send me a PM if interested, I can get you some things to start up with

this pic32MX360 has USB OTG device and host and heaps of functions at 80Mhz and would easily fulfill requirements for something like android or Âµclinux

Sulaiman

Tue Feb 04 2014, 03:05PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

just about every project that I had not put in an enclosure with decent terminals etc. has ended up re-cycled or lost.

Aren't there loads of little uC boards on eBay for most requirements?
If you are considering selling a multimeter-type thing,
consider safety isolation VERY CAREFULLY !

Andy

Tue Feb 04 2014, 05:58PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

I was thinking about having a rectangle shape with "u" shape connection on the ends for people to put there hand in between, so they can use it one handed.Once the tests were done, was going to put expandable form in there, with the idea the case can be dropped from the roof of a building and still work.

What plastic type would you use?

Don't know much about uC boards, I'm guessing there would be something like this out there. Planning on having more than just the multimeter, hopefully have space to put alot of stuff the trades would use, electrician,cabling technician,surveyor.

Cheers

Andy

Fri Feb 07 2014, 06:52PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

I'm planing on installing a LCD, I've got this one I'll like, but the connection is SMD, what do you need to do to join this to a PCB, I don't know were to start with SMD soldering.

Thanks

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