HM for a B+(work in progress)


 
Ahhh yeah, thats one thing is kinda hard to change. The probe side needs to be somewhat clear of the pi, and on the otherside you have the usb connectors in the way. There is really no need to go smaller on that side either, as you still have to have the lcd connected and have some amount of visual appeal of the lcd and the button(s) on the finished product.
 
I did some tidying up of the board and made sure I labeled everything. I did some test fits with a B and it would make a case that would need to be about 7.62mm wider then what we have now. When the board is attached to a B+, the case is basically the same size that we have now.

This board is in no way to be a replacement to the Heatermeter and is merely a Custom board of the 4.2.4 version of the Heatermeter. I was bored and have been having fun with eagle and designing boards. I did a OSH order for 3 of them and ordered some parts from mouser to see how it works. The parts list from mouser( including the TC components), not including Atmega header, TC Jack, and I think a one or two other parts came to about $41.
 
And after making some observations, the HM(smd) board could in theory be soldered directly to the B+, without a 26pin header, granted that you remove the unused pins on the B+. This could make the overall height smaller also.
 
any chance you could put dead holes in place for the extra pins on the B+ header so the rPi and HM could direct mate without removing those pins?
Though I can think of more than a few reasons why one wouldn't want to permanently solder their rPi to the HM...
 
Personally, I have no interest in soldering anything directly to my RasPi. It doesn't happen often, but folks have accidentally nuked their RasPi, and being able to easily remove/replace it is ideal. I've got a Pi that works 95% but for some reason the SPI function won't work and I'm unable to flash the Atmega with it, but it still operates fine in every other aspect.
 
Steve_M said:
Personally, I have no interest in soldering anything directly to my RasPi. It doesn't happen often, but folks have accidentally nuked their RasPi, and being able to easily remove/replace it is ideal. I've got a Pi that works 95% but for some reason the SPI function won't work and I'm unable to flash the Atmega with it, but it still operates fine in every other aspect.
Click to expand...

Yeah, same here, would I do it myself, hell no, but it looks possible if someone wanted a slim down Heatermeter and PI.

Ralph, with a 26pin header there wont be a problem of the extra pins on the B+. There is nothing that would hit the pins. the FQU11P06TU is there but its flush to the HM board and would not hit the pins
 
Here is a scale print of the board and compared to a 4.2.4

wi6em8.jpg
 
The HM works fine except for the Button, somehow I have the resistors all screwed up. when I push to the left it cycles the menus, all other directions, nothing. The hardest part was trying to figure out pin1 of the shift register and the Diodes were a pain in the butt to see a line on them.

Im am having a problem with my B+, which is not related to the HM smd. I was able to program a Atmega328 using the B+, but it does nothing else. The lights stay solid. when I install NOOB on the sd card it seems to work, then back to HM software, I get nothing.

The HM smd does work with a B and I will be using to smoke some pulled beef, tomorrow.

2uy2a0x.jpg


Oh, if you look at the pic, you can see a resistor(through-hole). I forgot to order a 22k smd resistor, oops.
 
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I thought I would give an update:

Well the first board version, I have made, had a problem with me over thinking what parts to use for SMD and their connections. I accidently reversed the Gate and Drain on the mmbf170(BS170). I could probably fix the 3 boards, But I decided to try redoing the board and I also changed the Atmega328 to the TQFP32-08 version of the chip. Its the same version of the Atmega just in a SMD square and it adds 2 more Analog only connections, not on the regular HM Atmega328. They are unused for now. After, looking at the chip its a pretty easy chip to solder. The hard part will be getting all 32 pins lined up.

I also went back to using the through hole versions of the Diodes, as the SMD versions are very hard to figure out which way they are to be soldered, the markings are not great, even with magnification I could not tell which direction they were to be soldered.

I should get version 2 next week
 
When soldering 0603 Diodes/LEDs, I use a multimter with pincer/tweezer probes to confirm I'm putting it in the correct direction (Diode test mode will light up the LED if you have it right). Wish I had pincer probes with needle-tips, I have to put the diode down, grab tweezers, then try not to spin it. Or breathe...
 
I have a radioshack special, lol. Yeah, i must have spent like a hour trying to figure out looking online, data sheet, and wondering if I actually see a line on one side of the part or a dot. Then realizing through part does not add that much more space, and there was to much grief with the smd diodes, so back to the original through hole versions.
 
My cheap meter does better lighting up LEDs than my better one. $6 for the tweezer probes on amazon. 5x magnification is useless to see the line on LEDs.....
I agree they don't save that much space for the PITA they can be. Next project I do, I need to come up with something to pick them from the tape.
 
Andy Snider said:
Next project I do, I need to come up with something to pick them from the tape.
Click to expand...
I stumbled across one of these when I was searching for a handheld suction pen. Beadsmith Pick-it-up It is the greatest asset to SMD placement I have ever used, much easier than tweezers. I bent a solder paste dispensing needle and stuck it on the end and it can pick up anything from a 0603 to an ATmega328 QFP-32. The suction is adjustable and for 0805 I can place the part and the solder paste pulls the part off the tip. It makes things wicked fast because you also don't have to fight to get the component out of the tape hole.
 
A slow day today on the forums, So, I figured I would post my new boards I will be soldering up, tomorrow. Hopefully they work, lol.

a0ca6b.jpg
 
Well, I tried, I had fun designing and I learned a lot but, I just can't get the dam thing to work, So I give up and call defeat. I really like the smaller board. I like the fit with the B+ and it can also work just as good with the other Raspberry Pi's.

The last version, I received, the Atmega328 seems to be able to accept the Heatermeter software and it shows that the fuses are good. But, im not getting any communication or nothing on the LCD. I have not tried to troubleshoot yet, will this weekend. I may just get another Atmega, as I did have a little issue with one side and somehow had a bent leg that I had to straighten out and it may have broken. What's so frustrating is that I don't change the HM schematic, all I am doing for the most part is changing the package from through hole parts to SMD parts. Although, I had to change the Atmega in the schematic to work with a TQFP-32 and it does have 4 more pins then the 28 PDIP version, so I may have screwed that up.

But, anyways I call UNCLE for a little while anyways.
 
Here is the connections I used, I don't see any thing that may be the issue, although I did have some vias near the pads underneath the chip that may have shorted when I soldered the atmega to the board.

64ntw6.png
 
John, would you mind sharing your design, so that I can have a look at it. It would be a shame to let your work go to waste, especially when you already are so close.
 
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