M1HOG

“Those who hear not the music, think the dancer mad”

LC Meter Kit - SADARS Club Project

14th September - New capacitors
I have sourced some splendid 1% 1nf/1000pf caps, they are big and green and were marked 10000n0 - but are the correct value and price! Paul G8IUG kindly supplied some more LCD displays so there are now enough for the remaining club builders. These are the last parts for the kits. Just need to find some cases at the right price..

12th August - New inductor
I fitted the new 82uh inductor today from the final part of the kit. Certainly more stable, although it was not to bad before. Seems to work really well. Updated the construction notes and photos page

7th August - Delivering the kits
Handed out the second part of the kits at the club tonight. Various people had construction and parts questions, and good building progress was made.

17th July - Bagging up
Bagged up the first dozen kits. Still need, the two caps, standoffs, two switches and inductor. Plenty for everyone to be getting on with though, and hopefully get some good deals/find the remaining parts in the next few days. 

16th July - Programmed
I think the 25 PICs had been sent Steerage, but they finally arrived today. Programmed each PIC using Piklab and my PIC header. After programming, the Piklab run command kicked each freshly programmed PIC into life displaying the now familiar "Calibrating" on the LCD, a good test.
The turned pin socket is not quite a ZIF socket, but with care was OK.
Updated the SADARS project page and started the construction notes and photos page Essential reading if you are building the kit, not sure how the photos will progress, but it is a start and illustrates a few details.

14th July - Power up
Seems the plug for the LCD data lines needed re seating, then the display fired up. The pins might be a bit too long. I also resoldered the pins underneath for good measure. Did not need to touch the LCD display trim pot. Measured the LCD bias voltage as 335 mV, useful to know for future reference.

13th July - Power up?
Did a bit more building this evening, greatly modified a pin header to fit on the board for the LCD connection. As my display is 20*4 and somewhat larger than the 16* 1 for which the board is designed it will be mounted separately and connected via ribbon cable. Then soldered in a 18 pin socket for the PIC, so I can remove and reprogram it if needed.
I thought the power up would be straightforward, but no display. No bias voltage is getting to the display, no matter where the trim pot is the output to the LCD is at ground. Needs some investigation tomorrow.

12th July - Starting
Started building my kit. Photographing as I went. Got all the passive components in that I currently have. Added some more parts to the kits - link wires and header pins to make up JP1.  

11th July - Regulation
Added 5 volt regulator to the test board and had a first proper look at the code and read the G4HUP manual again.

9th July - The PCBs arrive
The G4HUP L/C Meter PCBs arrived today, they look great.

7th July - PIC Header and LCD Test Board
Came back to it this morning. Checked the connections to the oscillator as the display was the same if the oscillator clock was connected or not. Checked under the magnifier light, perhaps there was a short, checked with the meter - had a short between one of the oscillator clock pins and the next I/O pin. Removed that, and then got rubbish on the display, but progress. Useful to know that a working oscillator is not necessary for successful programming.

Checked the data lines, one was swapped around. Works now, just shows "calibrating" then "over range", but that is fair enough as most of the L/C meter circuitry is missing! But, it shows all the PIC programming chain works and my junk box LCDs are fine. Thanks GM1SXX for the PIC.

Might have a look at modding the software to use the 20*4 display better.

The HVP or VPP as they call it for the 16F is 13 odd volts, can use LVP but needs another pin (PGM)! The L/C circuit uses VPP programming to save that pin. Puts VPP to the MCLR pin when programming.

Collected more donated parts - Thanks everyone. The PCBs, crystals, and a number of other parts are expected in the next few days.

6th July - PIC Header for ICD2 programmer and LCD Test Board
Never had much luck with LCDs and PICs, so decided to add an LCD display to the programming board to further test the PIC and LCD. PIC programmed fine, but no display on the LCD. Checked the connections to the LCD several times. Adjusted the 10K trim pot and got a few blocks showing that power was getting to the display, but no characters. The circuit specified a 5K pot, but fortunately the 10K, that I have hundreds of worked fine. Checked the board again still no display. Left it all for the night.

5th July - Sorting and PIC Header for ICD2 programmer
Sorted all the components I currently have for the kits. Quite satisfying seeing the individual piles of bits grow. At least everyone will get used to identifying parts! I used an Aldi multi compartment box, 48 compartments for £4, worked well, I even have some neat little poly bags for the completed sets of parts. Almost organised!

Discovered not all the 33pf caps I had were 33pf.. so got to fish them out of the boxes.. People will get confused, and we don't want that.

After rather too much fiddling I got the programming header for my ICD2 built and working on the Mac using Piklab. Basic issue was that I had forgotten about the details of high voltage programming (13.5v) verses low voltage (5v), and unfortunately had neglected to accommodate either on the little board I built! So when I understood that, it only needed one extra wire to strap MCLR to VPP and the programming worked! Phew. I was beginning to wonder if I should just use XP and Mr Wong.. Crisis over. I am back up to speed on HVP vs LVP now!

I have a couple of "junk box" LCD displays, so I am going to see how the pin out matches with the kit. They are 20x4 displays not a 16x2 but who is counting. As I have the L/C meter source code I might be able alter the code to better use the 20x4 display.

4th July - Sorting
Started kitting the 25 LC meters. 25 gets us to price breaks for the bits we will need to buy and hopefully gets the project - out of the door - in a sensible time, as the members are very keen to start building.

4th June - MPLAB X, PIKlab and PCB decisions
As GM1SXX suggested I changed the problem and loaded the old MPLAB software that supports the ICD2 onto the old XP box. I was then able to update the firmware on the ICD2 for the 16F chipset - as you do. This got things straighter... Plugged the ICD2 back into the Mac, and the Piklab programming software found it and started to give sensible answers.

Just need to make up a little header from the ICD2 to the 16F and find 9 volts from somewhere, as the USB does not have enough power to
program the PIC - unlike old style serial!

So it is getting there! Should mean I have the best of all worlds as I can use the MPLABX tools if needed on the Mac and program using PIKLab
also on the Mac.

Always good to get these things started as soon as possible so I can see what the issues are. Even if I have not chosen the most straightforward route. Just wanted to use the Mac and reuse/not buy any more bits if at all possible.

After looking at various PCB options I decided to use the excellent G4HUP L/C Meter PCB as the basis of our kit.

29th May - MPLAB X
Keen to use my Hackintosh Mac for PIC development as it is now my main machine.
GM1SXX sent me a couple of PIC 16F728A chips. I had a look at the latest MPLAB X and it supports OSX - which is great, I thought - but fails to support
the ICD2 programmer that I have. The previous version supports ICD2 - but only on Windows. Of course this all took a while to figure out - Oh well.

Now it is back to XP or find an OSX ICD2 program. Not really keen on a £145 ICD3 programmer to program/debug my £2 chips!

May - 2012 SADARS Club Construction project - The VK3BHR L/C Meter
Several club members were keen to build a PIC based project. The VK3BHR L/C meter was suggested. This is a great design which will make a very useful item of test equipment and a good opportunity to learn about PIC's. So, dear reader the story begins...