Help with new v4.1 build

I ordered all the components to build a v4.1 board years ago but never built it. With Thanksgiving coming up I figured I would finally put this thing together. Assembly went fine but I am having a heck of a time getting it to boot up.

Two questions

Is there a voltage diagram available for the v4.1 board so I can probe to see if I am getting the proper voltage where it needs to be?

What is the latest version of software that supports the v4.1 board?

Personally, if someone has a v4.2 board to sell you I would build that instead, the cost of the board would be worth the improvements. The 4.1 board wasn't the best design, had a different blower circuit, no RC filters, the probes picked up a lot of noise.
That said, I made a thread that showed how to mod the 4.0 and 4.1 to have the 4.2/4.3 features, it's posted here...
https://tvwbb.com/showthread.php?50543-HMv4-0-to-HMv4-1/page3
Adding the RC filters is a very cheap and simple improvement, the blower circuit update is a little more complex and nets a less dramatic improvement.

I understand that and will probably order a 4.2 or 4.3 kit soon. The issues with 4.1 started coming out right after I received all of my parts and is one reason I kind of shelved the build. I already have the 4.1 assembled and don't have time to order and build a new one before Thanksgiving when I would like to try it out.

Right now I am looking for resources to see if I can get what I have, working.

Any help is appreciated.

OK, I missed the part where you said you already assembled, I thought you were saying you were going to assemble over thanksgiving... Since the parts list is pretty much the same if it was still unassembled you could have gotten a V4.2 board and built that up instead, but I guess that ship has sailed.

So let me try to help you get the 4.1 up and running....

First of all, all the HM versions are pretty much the same besides a few minor changes, as far as I am aware they all support the same firmware, so you should be able to run the latest. The one thing you cannot use on the v4.1 is Voltage mode on the blower, that is just a config setting.

Moving on to troubleshooting, you want to start out by checking the various stages of the power supply. 12V in from PS, then 12v into the OKI DC/DC converter and 5V out, then 5v into the MCP1700-33 voltage regulator and 3.3v out. You want to make sure you have the MCP1700-33 installed in location IC4, note that this voltage regulator looks exactly like the other small transistors on the board so it is easy to mix up, check the printing on the device to make sure you have it right.

If all of your voltages in the power supply are reading right then you should move over to checking the rPi. The HM will be DOA until the rPi boots and flashes the ATMega, you will most likely see black boxes on the LCD until this happens. Speaking of the LCD, did you adjust the contrast pot? If not, do that now, you may just be surprised by the NO PIT PROBE message when you do. If you see black boxes instead that means your ATMega has not been flashed. If that is the case you can plug a monitor into the HDMI on the rPi and see what it is doing, to make sure the rPi is booting all the way. Again, if the rPi is not booting properly the ATMega wont get flashed and the HM wont work.

Here is a link to the v4.1 web pages,

https://github.com/CapnBry/HeaterMeter/wiki/HeaterMeter-4.1-Hardware
https://github.com/CapnBry/HeaterMeter/wiki/HeaterMeter-4.1-Assembly

You should be able to find the info about that build you need there.

Post back here more details about what you are seeing and somebody will help you get it going....

There's no 4.1 test voltage image because I didn't do that until 4.3, but you can use the 4.3 as reference for all the ATmega pins apart from the one label BFB which is not connected on the 4.1 board. The probe inputs will read a little higher as well, but you're looking for 3.3V there. You can also check the pins on the Pi connector because those should be the same.

It might also be helpful to log into the HeaterMeter home page and go to AVR firmware -> Bundled firmware -> hm.hex. See if you're getting AVR fuses: ERROR or if the ATmega is actually flashing. If it is flashing then it is just a display problem, if it is ERROR it is either power or the SCK/ MOS / MIS / G25 pins.

I have seen the AVR Fuses: ERROR. I then went over the board with a hot iron and hit most of the pins again. After that I saw NO PIT PROBE once but it disappeared I haven't been able to get it back. Usually I just see black boxes and a yellow and green LED...

In hindsight I should have just ordered a new board...

It seems like there's a problem on the SPI bus or just the regular voltage. Check that 4.3 image I linked above and check the corresponding pins on your 4.1's atmega for VCC, RST, and AVC (should be all around 3.3V). If that is good then power it down and check without a pi attached, the continuity from MI, MO, SCK, RST (atmega side) to MIS, MOS, SCK and G25 on the Pi connector. They also should not show any connection to each other.

If you do decide to order a new board, email me at heatermeter@capnbry.net and I can give you a coupon code for 20% off to make it a little less painful.