2nd Prototype Board

2nd Version of the prototype board, near final version.

Changes :

- Removed R3 pullup from the output of the SFH6206
- Changed Level Shifting of RX line, now goes through 2 new FET
transistors Q7 and Q6 (BSS138 like I2C) and removed the connection of RX
from the TXB0108 (U5)
- Letting 2 TXB0108 of U5 ports free, I decided to bring them to
end users (if they need) putting 2 soldering pad JFREE1 and JFREE2 and
removed the pull down R12
- Changed soldering pad connection of TX/RX from Arduino to PI by
jumper because is we connect Arduino with Pi by serial, this will
conflict
during Arduino programming using FTDI cable. With jumpers we could
remove them during the firmware upload on the Arduino and put them back
after (much easier than solder/unsolder)
- Added a test led on PI I/O, because when I test program on PI I
do not have any indicator the program is working fine, so this led could
be
setup to blink in the program as visual test
- Added a new soldering pad to choose who drive the RST Line of I2C
OLED connector (I/O port of Pi or Arduino) letting user to choose what
will
drive this OLED by I2C (Pi or Arduino)
- Changed R10 and R11 value to 1K and R9 value to 470