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Sunday, September 8, 2019

Switch Module Updates

Posted 6:30pm

At this point the Clone Mister is working, so I could use it if I needed, but no rush yet.  Now I  get to work on the lights, a little more complicated, but I have working code to go by if I need to. I completely rewrote the Servo code and expect to do so with the lights, see what improvements I come up with. I look forward to the first click the high current relay makes as it switches my 600W HPS light on for the first time!

I'm going to have a rest before I get started.

Update: 5:30am

Well, THAT's not gonna work any more....

So much for my soldering skills on super tiny stuff.  I wondered why the Serial Monitor kept stopping, and then finally, I couldn't reset it, or even upload new code, and when I pulled the tape off, this is what I found.

There are pin-outs I can use to program each of the boards, but that's a mini project in itself, figuring them out, how to use them, where to plugs stuff in, etc...  In the mean time, I swapped in the spare development using, which actually works out well, since I'm doing development on the switch module :)  The problem will be if the sensor modules need updating or testing, this was the module I would use.

Update: 5:50am

Knowing where something failed is good, it gives you a chance to fix it, but knowing why, or how it failed is good because then you have a chance to prevent it from happening again.

In this case, I'm pretty sure I found the culprit...

On each side of the USB connector are tabs that get inserted into the two holes on the circuit board, and soldered in place. These two tabs will take the strain from the USB cable being plugged in and moving around.  It looks to me like both of these were cold solder joints, and they really weren't supporting much, that it was the tiny tabs soldered to the board that was holding it.  So some preventative maintenance will be to check all the Wemos Megs boards I have to make sure the  are soldered well.

I think I'll have a go at soldering this connector back onto the board, although to do so will be a small miracle given that I have essential tremors, and can't really aim the soldering iron that closely...

Update: 6:40am

That went almost exactly like I figured it would...

Two of the solder pads have lifted off the circuit board...  Sorry for the blurry picture, I'm at the limit of closeups with my phone. Now I need to figure something out, and order some spares, although they will take about 4-6 weeks to get here...

Update: 6:45am

I just noticed something in the picture, that reddish vertical line almost in the middle of the picture?  That is actually the lifted trace from the board, and you can't see it in the picture, but the other trace is also still there, just up in the air...  that means I know exactly where they go, and just might be able to fix this, although probably not a connector, maybe a permanent soldered connection?

Update: 8:30am

I have a schematic for this board, and was able to identify where the wires needed to hook up. This is the relevant part:

Unfortunately I didn't take any pictures, but first I soldered some very tiny wires (wire wrapping wire) to the end of the fuse F1 and to the ground tab on the power barrel connector receptacle. I then hooked the two data wires to the ends of the resistors, using the lifted, but still attached traces to lead me to the right ones. I hooked the + and - power wires to a USB cable which I had cut the end off, and plugged it in, and the board powered up! Fantastic...

I unplugged it, and hooked up the two data wires to the USB cable, and when I plugged it back in, the computer said the device was unrecognized :(

Reluctantly I ended up ordering another unit, it was less than $18 shipped with tracking from China.  I can manage without the development unit for the time it takes to get the new one, but this rams home the point of always having spares on hand...

Update 10:20am

The Mega Shield has a new feature, can you guess what it is?

I just happened to have some of these which I use to connect to the Pro/Mini's and other boards without usb connectors. They provide a TX/RX/VCC/GND/DTR connection, but I'm not sure what to do with the DTR line. If it just shorts to ground, I could hook it to the reset pin, I'll experiment and see, but meanwhile, I just plug a cable in and I can monitor the serial monitor, but if I want to upload a sketch, I need to push the reset button immediately after telling the software to start uploading. It's a pain in the butt, but it works. As for the ESP8266, I can still do OTA updates, but if I need to upload over the usb, Ill have to figure that out when it happens... I presume just connecting up to the pins directly.

Alright, time for a rest, then back to work. I have a dentist appointment at 2, so the day may not be so productive.

Update: 1:05pm

I found this online, it answers my question...

"Next you need to synchronize the bootloader. Either by manually synchronizing the Reset of the 2560 with the starting of the download (of AVRdude). Or by connecting the DTR(out) of the TTL Serial Port through a 100nF capacitor to the RESET pin of the Arduino."

Update: Sept 11, 2019  11:30pm

I tried the suggestion of putting a capacitor between DTR and RESET, but it did not work, in fact, I couldn't get into programming mode at all by hitting reset, which was working.  I googled it, and it seems this person missed adding a 10K pullup resistor from RESET to VCC, so I added that as well, and still no joy.  So, I removed the wire, capacitor, and resistor, and will just hit reset manually. 

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