Using the NKC RGB LCD Shield with the FEZ Domino (Update)
Lately I’ve been doing some more work with the NKC RBG LCD Shield and the FEZ Domino. The biggest hurdle to getting the two to work together is the open collector outputs on the FEZ Domino at header pins 2 and 3. These cause the logic levels at the LCD chip select and reset to be at too low a level to be recognized correctly.
I described my original solution in a previous posting. It involves removing two sets of the 1K and 1.3K resistors used as level shifters on the original board and replacing them with a single 2.7K resistor. However after giving it some thought I realized there is a simpler solution. It works best when originally constructing the LCD board but can be used to retrofit an existing board as well.
Follow the construction instructions on the NKC Electronics Tutorials blog as you normally would except when you get to the part where you are soldering the pin headers, do not include the header on the lower right hand corner of the circuit boards (this is the set with the ‘*’ next to five of the pins). When construction is complete according to the instructions, get five short pieces of wire (wire wrap wire is perfect) and make the following connections:
- Pin 2 –> Pin 8 (CS)
- Pin 3 –> Pin 9 (RESET)
- Pin 4 –> Pin 10 (DATA/COMMAND)
- Pin 5 –> Pin 13 (SPI CLOCK)
- Pin 6 –> Pin 11 (SPI MOSI)
With these connections made, pins 8, 9, and 10 function as the chip select, reset, and data/command signals and the Domino’s SPI module is connected to the clock and data inputs. This not only allows use of the original boards parts, using the SPI module allows for much faster data transfer between the Domino board and the LCD.