Saturday, January 12, 2013

Ready for Software loading!

Tonight I finished assembling the controller board, and the LCD remote display board.

Controller board assembled.
(Note C6 & C8 has been left out, pending need to mess more with the INA-220s.)

Remote LCD interface board assembled

They are not that bad, if I say so myself...  And I found (so far) only one fatal fault, the trace widths from the 5v switching regulator to the large inductor is too small.  I added parallel external wires, using clipped off leads from the large bypass diodes

Beefing up the trace from 5V regulator to large inductor

The biggest issue I had was those SMD parts.  They are really tough to install using hand soldering irons.  Especially the Crayon sized ones I have.  Here are some photos I had taken while installing the INA-220s.   There was no way I could check the soldering of these devices, so I took photos at macro setting on the camera  and then enlarged them on the computer.  It was less then desirable, but worked - somewhat.

I had one of the INA-220 develop a short under the chip and had to remove it and try again.  Make sure you purchase extra ones of these parts!  There are lots of hints on the web for soldering small pitch SMD parts so I will not repeat them here.  Will say I found that after tacking a couple of corners (and taking photos to check alignment)  it was best to slide the soldering iron up the pad until it touched the lead of the INA-220s.  This seemed better then trying to solder from the top.  And I also used solder-wick to clean up bridges.  Ohm checking indicates these soldered, will see if the Amtel CPU can actually reach out and find the two INA-220s.

And as much fun as the INA-220s were, the small SMD diodes were just as much of a pain.  If anyone does one of these boards I would suggest starting with the SMD parts 1st before adding anything else.  And when updating the PCB I am going to add in a DIP-10 in parallel with the INA-220s to optionally allow a MSOP-10 <--> DIP adapter   In this way one can solder off the main board (if they wish) and then install the DIP-10 module.  I may also convert the SMD diodes to through-hole parts.

Dealing with these SMD parts took perhaps 70% of the assemble time, and I am still not 100% sure of the soldering quality. . . .

And here you can see it all 'mocked up' with power applied:

The meter in the left is showing the units drawing 17.6mA at "12v" battery voltage while the meter on the right shows the 5V switcher output.  Between the main and the remote board you can see the external USB <--> Serial board.  This is plugged into the 'service' port on the main board to load software.

Next steps will be to load the Arduino bootloader into the Amtel CPU via the ICSP port.  And then start to check out the subsystems one at a time.  (THEN we can see how the SMD Soldering went).  But that is for tomorrow   For now I got two LEDS to light, and did not let out any magic smoke,  Time to celebrate.

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