Objective
This is first example on LPC1768 where we start with blinking the LEDs. In this tutorials we are going to discuss how to configure the LPC1768 ports for GPIO and then to use to send a low/high signal on it. Lets start blinking with LEDs and then generate the different patterns using the available LEDs.
Register Configuration
As all the LPC1768 SFRs(Special Function Registers) are defined in lpc17xx.h, this has to be included at the beginning of our project/code.
The Below registers will be used for Configuring and using the GPIOs registers for sending and receiving the Digital signals. A structure LPC_GPIOn(n= 0,1,2,3) contains all the registers for GPIO operation. Refer lpc17xx.h file for more info on the registers.
PINSEL:
Every GPIO pin has a minimum of one function and max of four functions. The required function can be selected by configuring the PINSEL register. As there can be up to 4 functions associated with a GPIO pin, two bits for each pin are available to select the function. This concludes that we need two PINSEL registers to configure a PORT pins.
By this the first 16(P0.0-P0.16) pin functions of PORT0 and be selected by 32 bits of PINSELO register. The remaining 16 bits(P0.16-P0.32) are configured using 32bits of PINSEL1 register.
As mentioned earlier every pin four functions as shown below.
Lets see how to configure the 0th bit of PORT0 register using the PINSEL register bits.
| Value | Function |
|---|---|
| 00 | Primary (default) function, typically GPIO port |
| 01 | First alternate function |
| 10 | Second alternate function |
| 11 | Third alternate function |
FIODIR:
FIOSET:
FIOCLR: