how much difference you are seeing? if its consistent and within +/- 0.5 degree Celsius then its ok.
ds18b20 is not the most accurate probe (like pt-100), but its inexpensive , easy to source and very well integrated with the linux ecosystem. Hence we use it. It has a precision of 0.5 degree celsius, which i think ok for our use case. It is important for us to check its precision (i.e. if its off by less than 0.5 degree celsius, its consistently off).
Nope :-/
Its 12 v. So, 8 channel each connected to the 8 data pins, and GND is actually connected to 12v+. This is because uln2803 is a sink type driver. Let me know if you need further details, happy to share build pics as well (i have shared them earlier in a post i think)
I dont know if the outershield is same as the GND pin. For hdmi connectors thats the case.
Yes the standard options are ok, I only don't understand why it states 5 boards, normally it's 10 (which you probably don't need). Also used Green as color, but if red is the same price and your preference, that's ok :D. I think I tried Black and it became more expensive, so I stayed at Green. Please wait with the PWM board, I've made a new PCB the size of the PI which should fit directly on the HATHaha maybe I should get into the habit of using Oz instead of Aus to avoid confusion :p Good to hear you had such a great time that you came back though :)
And no worries about the photos, I was keen to see the HAT on the Pi with all the connectors soldered on and hooked up to their equipment. But if you haven't got a tank yet I can understand why that might not be done just yet :)
When ordering from JLPCB are these the right options? It looks like the ordering 10 x Pi HATs and 10 x PWM boards to Oz will only cost $7 for the PCBs and then $20 shipping. That's cheap as! (the $20 shipping is with DHL as I don't really trust the cheaper option and it's cheaper to order both at the same time to save on the shipping).
I'll probably wait until you test out the PWM board before I order as I will still have to wait a little while to get all the components anyway :)
Spot on, this is one of my all in one build, notice the db9 connector wiring, uln2003 is soldered on the perma proto board. wire colors indicate power or gpio inputs. I would recommend using ULN2803 going forward, since it has 8 channels and can support higher current load.Outer shield is NOT grounded or required.
I just finished setting up this, personally.
I used a ULN2803 IC as the control. As Ranjib said, a ULN2003 will work just fine as well, with the limitation of 7 input/outputs instead of all 8.
Really is as simple as connecting all of your GPIO's directly from your PI into ports 1B through 8B, GROUND to pin 9 of the IC, +12V to pin 10 of the IC, and pins 1C through 8C are the GPIO controlled outputs to the power strip. I used a connector like this to make hookup easier, and a standard off the shelf DB9 cable to connect to the power strip.
On that specific power strip, +12V is connected to PIN 5, and the other 8 pins will be your relay triggers, pulling to ground.
A completely acceptable alternative would be to pick up two of these:
Search for "ULN2003 stepper driver"
In that case, supply GPIO from your PI on the IN pins, ground and 12v at the labeled pins. Buy/plugin the appropriate 2.54mm JST cable, https://www.amazon.com/2-54MM-Femal...UTF8&qid=1534303070&sr=8-9&keywords=5+pin+jst and you are in business.
The 9th port on the power strip is constant ON.
which one? you mean a scratch built powerstrip, with 5v relays?
argh, forgot to include the link....
Yes the standard options are ok, I only don't understand why it states 5 boards, normally it's 10 (which you probably don't need). Also used Green as color, but if red is the same price and your preference, that's ok :D. I think I tried Black and it became more expensive, so I stayed at Green. Please wait with the PWM board, I've made a new PCB the size of the PI which should fit directly on the HAT
I tried soldering the PCA9685 but it didn't work due to several reasons:
* My eyes couldn't see the tracks clearly while soldering although I normally can see close very sharp. Could have been the light condition.
* Wrong solder iron tips (sharp, was bending the housing pins and damaging silk screen). Looking at more youtube video's it became clear they mostly used broader/flat solder tips
* Shaking hand, which is a decease I unfortunately have since youth
Found on youtube an interesting video where you just position the chip with a normal solder iron (bottom/left and upper right which worked fine for me), then just place solder paste over all pins and then solder with the hot air gun.
have a look from 5:45 at
Also found a lot of other video's showing that SMT components like resistors position themselves when hot air is applied. I do know however from my former employer that components may 'flip up', applying solder paste for high volume production in a reflow production line (meaning millions of components) is critical (meaning reaching low PPM values). As a trial I also ordered a stencil for the PWM board from JLCPCB, there are interesting video's for this as well, for instance:
In the meantime I have:
* Ordered the new board as shown above, used standard shipping this time, not DHL. In the Inet I found usually 17 day's shipping time. Have to wait anyway for the other equipment as well.
* Ordered different solder iron tips (broad and SMT specific) (14USD)
* Electronic magnifying glass (48 Eur)
* Hot air solder station (40 Eur) with solder paste (18 Eur)
