The level shifter came in this week.
Populating the board:
I installed parts out of my kit in the order that I grabbed them, until I had enough to do the basic test. The board powered up and the blue LED on the ESP-12F blinked once. Unfortunately the board wouldn’t program.
I started probing with my Oscilloscope. The serial data lines looked normal when I tried to program the board. Then I looked at Reset and GPIO0 lines and found that GPIO0 was oscillating at 24 MHz. The Reset line was working as I expected it to. I used a 1 MOhm resister as a pull down on GPIO15. I chose 1 MOhm to reduce the amount of current when A_Sel is High. I knew this could cause me trouble, GPIO15 is used to put the chip into SD card mode. That may be too much resistance. I changed that resistor to 10 KOhms to see if it made a difference. It did!
I uploaded the defaults, then my code. My simple serial menu came up in the terminal. With it working, I went on to populate the rest of the board. I came up short 2 components, the pin header I use for the lithium cell and Q2. I grabbed both of those from the last build and completed populating the board. I reconnected it to my computer, re-connected the serial terminal and the serial menu is still working.
SPI RAM Testing:
I re-enabled the SPI RAM test code uploaded it and forced a reset. I got a Hello World response. Enough said!
The new board is assembled, and I know that the SPI and USB to serial bridge are working correctly. The next step is getting the voltage regulation control loop running reliably. I also need to get the Bill of Materials updated and do an inventory of components. I have used some components from other projects on this one and used some from this project on others.
Short post this week, most of my time spent on this project was soldering the components on the board. I am looking forward to getting full functionality tested in the next few weeks.
Do you solder your own boards? What does your bring up procedure normally look like?