These are the pins that are involved with powering the RA8875:
- VIN - power input, connect to 3-5VDC.
- GND - power and signal ground. Connect to your power supply and microcontroller ground.
- 3Vo is the output from the onboard 3.3V regulator. If you have a need for a clean 3.3V output, you can use this! It can provide at least 100mA output.
All pins are 3-5 V compliant, so you can use with 3V or 5V micocontrollers
- SCK - this is the SPI clock pin, its an input to the chip
- MISO - this is the Microcontroller In Serial Out pin, for data sent from the RA8875 to your processor - this is 3.3V logic output, and can be read by 5V microcontrollers just fine. This pin does not tri-state when the CS pin is pulled low, so it cannot share an SPI bus without a tri-state chip like the 74HC125 or similar
- MOSI - this is the Microcontroller Out Serial In pin, for data sent from your processor to the RA8875
- CS - this is the chip select pin, drop it low to start an SPI transaction. Its an input to the chip. This pin is not pulled high by default! Please either set it high or add a pullup resistor to keep the chip disabled!
These are the pins that are involved with the touch panel for the RA8875. The X an Y pairs of pins are ideal for reading touches using an external touch controller such as the STMPE610:
- INT - interrupt pin that goes high when the panel is being touched
- Y+ - touch panel Y positive signal
- Y- - touch panel Y negative signal
- X+ - touch panel X positive signal
- X- - touch panel X negative signal
These are the remaining pins for the RA8875:
- LITE - PWM Signal used to externally control the Backlight
- RST - Reset line for the RA8875. It is active low meaning you would reset the RA8875 by pulling it this pin to ground.
- WAIT - output to indicate that the RA8875 is in a busy state. The RA8875 can't communicate with the microcontroller when the wait pin is active. It is active low and could be used by the microcontroller to poll busy status.