I have the following SD card reader on the left side from Sparkfun. In the tutorial they have it connected directly into an Arduino Mini, which has BLK and GRN pins> I would like to connect it to an Arduino UNO. Where do I connect these pins or can I ignore them? Thanks for your help.
If you read the page about the OpenLog board you can see (on the schematic link) what the pins mean:
I've added the labelling on the board in blue. The GRN pin (DTR in the schematic) is actually an input, which resets the chip:
GRNshould be connected to RESET on your Uno, so that when you reset the Uno, you rest the OpenLog.
TXO(transmit out) on the OpenLog would be connected to serial input on the Uno (ie. digital pin D0 - labelled RX).
RXI(receive input) on the OpenLog would be connected to serial output on the Uno (ie. digital pin D1 - labelled TX).
You can see that
BLKare both ground pins, and thus should be connected to ground.
VCC(RAW on their schematic) is the voltage input to the 3.3V very-low-dropout voltage regulator MIC5205 on the OpenLog. This will accept input voltages in the range 3.3V to 12V. (The datasheet seems to suggest a maximum of 16V, but it might get rather hot if you did that). Connecting VCC to +5V on the Uno would be satisfactory.
It quite simple and stupid that they named the pins with those name. You simply connect:
BLK > ground
GRN > RESET
The weird pin abreviations can cause quite a bit of confusion.
Extra links for help.