Video of DRO Operating

Video of DRO Operating

I've made a little video of the DRO operating so you can see how fast the update rate is. It's several readings a second and easily fast enough for anything I do. The gauge data stream is pretty fast and all six channels are read by the main processor over I2C, only three are displayed.

The main TFT is quite slow with big updates, but just about responsive enough when I use the menus.


One thing I was worried about was the auto power-off that the gauges have. After a period of inactivity they shut down, but fortunately all they do is turn the display off. The data stream continues, which is perfect for a DRO like this. It also might explain why the batteries go flat so quickly...

Latest OLED Watch (Isn't OLED)

The OLED watch project started when I saw some small OLED displays on ebay and thought 'What can I do with that?'. The watches followed, but there was always the problem of the power consumption of the display. I manage about 400 hours of use from a rechargeable 2032 battery, more from a non-rechargeable (the capacity is higher).
So, I had a look around and found a lower power display, one of the Sharp memory LCDs. These are very low power LCD displays.

A redesign of the hardware to drive the LCD was needed as the display isn't I2C, it's a serial bit stream. The hard part of using this LCD was finding a way to solder the 0.5mm pitch connector on to a PCB. Milling that connector was challenging as well. In the end I got a new soldering station so I have hot air. I also have a stencil for solder paste application. As well as milled PCBs I had a few made up by Dirty PCBs so I have a full solution if I need it.

The code was adjusted and the display was up and running.

The PCB is reversed due to the layout of the display connection. It's a cleaner look, but less interesting. I may revisit that in a later iteration.
The battery has also been reversed.

The overall watch is as thin as the OLED one and is very wearable.

So far the battery life seems to be far in excess of the OLED watch. The display update takes 20ms and to get power consumption to an absolute minimum the display is updated every 5 minutes. I'll see what real world battery life I get from this and then decide on what update rate I'll settle on.

MPF-1P

Microprofessor MPF-1P

I recently bought an MPF-1P, which is an old Z80 training board. The one I got was in a bit of a state. The crystal had been removed, as had the processor. There were no ROMs and the 7805 regulator had also gone. The display power supply wasn't working as a transistor had blown.
These old bits of kit are very fixable, as the schematics are findable, and the PCB is all through hole technology.
I had all the parts I needed to fix the MPF in my parts bins, and got to the stage where the display had a scanning across all the digits. When the reset key was pressed the scanning stopped. I had found a ROM image online, but it had 'BAD DUMP' next to it, which was suspicious. I put out some feelers via email and on a forum (EEVBlog) and within about 5 hours I had a reply that listed a site which had many images and files. One programmed 2764 later and the MPF is alive:

I have some other images I'm going to try, but unfortunately I found that my old EPROM eraser no longer erases. I think the bulb has gone. As it's cheaper to get a new eraser from China than buy a new bulb (if I can foind one), I've ordered a new eraser. It'll arrive in about four weeks I'd think, so things are on hold for a while.

After this success, I thought the keyboard deserved a clean:

DIY DRO

All Gauges Attached to DRO

The remaining gauges have been attached to the DRO. There's now 3 gauges on the lathe and three on the mill. All of the gauge channels are now populated and attached:

Each card has a PIC on it that converts from the gauge serial protocol to I2C. The main ARM processor then interrogates each of the relevant gauge channels over I2C and displays the values.

Each of the gauge channel PCBs is identical, the firmware is almost identical, the only difference is the I2C slave address, which is 0x30 and 0x40 for each pair of PCBs on the same I2C bus. There's three I2C busses.


The main DRO PCB has an ARM processor on a commercial LPExpresso card:

The TFT screen is a touch screen and there's a menu system running on it. The DRO can be set to display the lathe channels or the mill channels. The smaller OLED displays then show the appropriate axis tags. When running in lathe mode the two X axis values can be added together.

The gauges have been attached with 3D printed plastic mounts. I may re-make them in metal if they aren't rigid enough.

The gauges are held in clips that can have screws clamping them from the sides:

 I've removed the buttons from the gauges if they were pressed by the clips. The buttons aren't needed and you also don't need to read the displays as the DRO does that.

The batteries aren't needed either as the DRO channels all have a 1V5 power supply. The gauges run from that and are powered all the time the DRO is powered. The power down of the gauge display doesn't stop the serial data stream, either, which is nice.

 The mill X gauge is mounted in a similar way:

The Y as well:

And the Z gauge:

The lathe bed gauge was one of the more complicated mounting arrangements.

I've started to use the DRO and it certainly makes measuring things much easier. I need to check that the gauges are working correctly by comparing with a dial indicator.

Picture Frames

Three picture frames were required for a significant day. I thicknessed some offcuts of scaffolding board and mitred the corners. Some glass from our old windows was cut down. An old box was used as a backing sheet.

I normally glue frames and hammer sprigs in for support, but this time I used proper V nails manually hammered in. They worked well, so much so that I didn't need to clamp the frames as the glue dried.

When You Have a Remote Control RGB Lightbulb...

... you always turn the lightswitch on and off instead of using the remote. It's just habit. So, one of these is needed:

the light switch is still accessible:

Latest OLED Watches

The latest iterations of the OLED watch are finally approaching wearable. Well, the first of the two is wearable but a bit thick. The second is much more wearable size.

The first iteration is the smallest PCB so far fitted into a 3D printed case and mounted on a cloth strap latched with velcro.

The switches are mounted on the top and the clear front flexes when they are pressed.

The overall thickness is 15mm, which is a bit too thick to wear comfortably. It gets caught on sleeves and catches easily on fabric.


The latest iteration is a one that doesn't use a PCB. This removes 1.6mm of thickness immediately, but makes the construction more manual.

The wiring is manually laid out and not very tidy. the thickness is much less, at 9mm, or 10mm to the tops of the front cover screws. Compared to my main watch this is very similar.

The components are mounted in a 3D printed frame like this earlier version:

The minimum thickness is fixed by the switches that I have used. The wiring adds a millimetre or so to the thickness, that could be reduced by inlaying the wires into the frame. More use could also be made of the 3D space in the frame. At the moment there are no components on top of components.

Using a PLA 3D printed frame is useful as it is possible to heat components and wiring up with a soldering iron and push it into the PLA. This then holds the component firm when the plastic cools.

There may be a better way to wire the components, maybe using a smaller PCB that just has the surface mount components on it.