KNOWN ISSUES
Alex Lee Sept 2012

The use of two different packages for the 220R resistor packs was unintentional. R13 and R15 (2NBS16-8 SO16) should be replaced with Bourns 4816P-T01 as the former part is obsolete. The pads on the PCB will need to be adjuusted

The PCB-mounted microswitch S1 is conneted to the same GPIO pin as the [left?] bumper switch (GPIO18), limiting its usefullness.
S1 switches to +3.3V whereas the left bumper switches to GND so as a workaround it should be possible to check the state of both by toggling the internal Pull-up/down resistors of the Raspberry Pi.
Current limiting resistors prevent damage if both S1 and the bumper are pressed simultaneously but the bumper press will be impossible to detect as GPIO18 will be strongly pulled high

Do not fit C5 (NFC will not work if fitted)!

C12 is redundant

Q2 is a strange use of an N-type MOSFET (BS170)

R18 and R19 should be 0R for reliable i2c communication. However this removes over-current protection so use these pins with care. If use as GPIO is planned, consider fitting R18 and R19 as 220R but note the limitation that internal pull-ups in the Raspberry Pi (and R31,R32) will always be active.


