Interesting PIC Project - 16 Function Probe

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eblc1388

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Hi,

I would like to recommend the following to anyone interested in making something nice with a PIC. The image shows the schematic and the actual probe built on my breadboard.

**broken link removed**

It is a probe with 16 functions which includes:

- Logic Probe
- logic pulser
- Frequency Counter
- Event Counter
- Voltmeter
- Diode Junction Voltage tester
- Capacitance Measurement
- Signal Generator
- NTSC Video Test Patern
- Serial Port tester giving out Ascii characters
- Midi Note
- R/C Servo tester
- Sqaure Wave generator
- Pseudo Random Number generator
- ir38 infrared red LED driver
- PWM waveform output (6KHz, 3% to 97% duty cycle)

As you can see, the schematics is very simple and no additional transistors or ICs required. I use a 16F876 and programmed the hex code by the author into it and it work as expected.

The author has also provided the source code to the project so one can learn the technique in implementing the different functions using PIC.

There are also other PIC projects in the above website so you can look around. Most of them have schematic, object code and source code for download.
 

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Prety nice!

All that whith almost nothing but an PIC.

Wen i seen the feture list i toght: Oooo this must be a huge circuit.But i lost my words wen i seen the schematic.
 
Someone Electro said:
Prety nice!

All that whith almost nothing but an PIC.

Wen i seen the feture list i toght: Oooo this must be a huge circuit.But i lost my words wen i seen the schematic.
Click to expand...
I am glad to see you back Berni
 
Yeah, thats a cool probe. A guy could get used to nothing else...

The author also has a couple of other interesting projects on his site.
 
that is awesome I even have one of those exact same radio shack logic probes at home that I could gut to build it in!

However, I'm very tempted to modify it to use an LCD instead, as I have some nice tiny little 2x8 character LCD's I can use...

just what I needed, another project... as if i had any free time left to spare :lol:
 
You could even get away with using a 16F88 (my fav) instead of that big chip. If you minimize the pins needed for display by doing an LCD in 4-bit mode.

Uhhh...scratch that. I counted again.

Mike
 
I've been looking at this project for some time now, and as soon as I have a little free time I'll be building one in a RS logic pulser case that I just don't use (same case as the logic probe).

But I will probably try to use a hdsp-2112 display that I have laying around here. Too bad I can't find any asm code to drive this display, would have saved alot time when modifying the source code. The only problem with this display is that from what I can see, I will need 13 I/O pins to operate it. I did not read the Datasheet yet but I just might be able to pull it off with alot of tweeking.
 
Note:

If anyone wants to build the probe and have difficulty in get the display, you can use any commom anode 7-segment LED displays with decimal point, like I did in the picture.

I am fairly certain(but not 100% as it is not tried) the probe will work using any PIC from the 16F87X or 16F87XA series so you don't need to find/buy the particular PIC used by the author.

Have fun and modify the project to suit your needs. My take is to modify it to give a mode which shows me the HIGH time and LOW time of a rectangular pulse.
 
common anode vs common cathode

Bouncing up a very old thread but why open a new one when old one exists and this is still a nice project

The original super probe uses common anode 7seg display's .. I got request from a friend to make changes in the app so that he can use common cathode 7seg's.

Here it is, use exactly the same schematic as on Super Probe only abcdefg and dp are anode and rc0-rc3 go to C1/C2/C3/C4 (common cathode)

Attached, mplab asm and hex file

EDIT: attached proteus7 dsn file
 

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This is my version of the superpobe software allows one to remap the LED to PIC pins for easier PCB routing. Assembles in MPLAB.

It uses the following to do the mapping. These defines are used in place of constants in the original code.

Code: 
; map segments to PORTB bit positions, bit0 to bit7
;    my segments are such that
;    1 -> 4 -> 8 ->1

#define _SEG_A  0
#define _SEG_B  1
#define _SEG_C  3
#define _SEG_D  2
#define _SEG_E  6
#define _SEG_F  5
#define _SEG_G  7 
#define _SEG_DP 4

; map bit positions to bit values
#define _SA  (1<<_SEG_A)  
#define _SB  (1<<_SEG_B)
#define _SC  (1<<_SEG_C)  
#define _SD  (1<<_SEG_D)  
#define _SE  (1<<_SEG_E)  
#define _SF  (1<<_SEG_F)  
#define _SG  (1<<_SEG_G)  
#define _SDP (1<<_SEG_DP) 

; values to display digits 0 to 9
#define _0  _SA | _SB | _SC | _SD | _SE | _SF              
#define _1        _SB | _SC                               
#define _2  _SA | _SB | _SE | _SD |             _SG  
#define _3  _SA | _SB | _SC | _SD |             _SG       
#define _4        _SB | _SC |             _SF | _SG    
#define _5  _SA |       _SC | _SD |       _SF | _SG       
#define _6  _SA |       _SC | _SD | _SE | _SF | _SG       
#define _7  _SA | _SB | _SC                                 
#define _8  _SA | _SB | _SC | _SD | _SE | _SF | _SG          
#define _9  _SA | _SB | _SC |             _SF | _SG          

; other characters
#define _C  _SA |             _SD | _SE | _SF
#define _H        _SB | _SC |       _SE | _SF | _SG

Hans and I have a small version of the super probe intended for solderless BB use. The unit uses a needle for a probe. The idea is that you insert the probe into the BB and leave it there hands free. It is small and light so that the needle can easily support the probe. The company supplying the display has messed up the order and we are waiting on them.
 

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niiiiiice

I built the contraption last night (when I finished the code for a friend) to try it in real life .. not sure if the buttons I used are bad or no software debounce exists (I just traced the portc use and reversed it so it can be used with common cathode 7seg's) but the device is completely useless .. will try to add some hw debounce after I change the switches .. maybe that's the problem ... also, it always get stuck in coil and capacitor measurement (the original one, not the changed one) ... but anyhow - interesting project
 
Getting stuck in coil and cap are a problem with the design.

Try different switches, I have not seen that problem on the ones constructed so far.

In general it is a good design.
 
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will look at the source ... might see something interesting .. looked only so far to reverse the signal .. will be nice to revisit the asm

will try other switches too
 
I have programmed asm for various chips but have not done anything with the PICs at that level. I can read it enough to figure out what it is doing and thats about it. Sort of been there, did that, not point in doing it again.

Fixing the coil and cap hang would be good. Also the 16F870 is getting old and expensive. Maybe time to move the code to a more modern maybe faster chip. While we are blue skying I would like to see a autoranging ohm meter function
 
3v0 said:
would like to see a autoranging ohm meter function
Click to expand...

That's what I'm thinking since yesterday ... I also tried out some interesting 24F chips .. and have few small dsPIC ones too (I have dspic33fj12nc202 28pin trough hole that I never took out of the original packaging .. have no idea why I ordered it) ... IIRC those are all 3V low power ... should be interesting to make autoranging, very precise, very fast, ohm meter ... (yeah I do believe dspic / 24F might be overkill .. but, why not .. maybe some 28pin 18f with ad's)
 
I've always hated the direct driving of the seven-segment display with the PIC, of course doing it with transistors and resistors almost doubles the complexity of the simple mondo-probe.
On the other hand a 16F917 can directly drive LCD glass...
 
yup it can drive the glass but you need to multiplex it in order to show more the 2 digits .. (the local store sell only static glass's )

I'll think about making some "cool" meter .. (will start with auto range ohm meter as that's what I actually need) and as for the "display" will think .. I might go with char screen as it is ~ money for me to put 10x1 char display then to put 5x10seg displays ... need to finish some simple project first that is messing with my head and then will think more about this one...
 
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