Lattice Semiconductor LatticeMico GPIO, Manual

LatticeMico32 Microprocessor Software Support

LatticeMico GPIO

19

intr_enable

unsigned int

This value is set to 0 if the GPIO is not configured to generate 
interrupts. Otherwise, the value is 1.

wb_data_size

unsigned int

This value determines the width of the WISHBONE data bus. 
Allowed values are 8 or 32.

lookupReg

DeviceReg_t

Used by the device driver to register the GPIO component instance 
with the LatticeMico32 lookup service. Refer to the 

LatticeMico32

Software Developer User Guide

 for a description of the DeviceReg_t 

data type.

prev

void *

Used internally by the lookup service

next

void *

Used internally by the lookup service

Table 9: GPIO Device Context Structure Parameters (Continued)

Parameter

Data Type

Description

Note

Y

ou may need to access the GPIO device registers directly, but some of these 

registers are write-only. Implementing shadow registers in RAM can be an effective 
way to replace this missing capability. Figure 14 provides an example of “shadow” 
register code for handling write-only registers in LatticeMico System.

Figure 14: Example Shadow Register Code Fragment

MicoGPIOCtx_t *pGPIO_context;
   MicoGPIO_t     gpioState, *pGPIO;

   // The GPIO is an OUTPUT only instance
   pGPIO = (pMicoGPIO_t *)(pGPIO_context->base);
   // initialize the "shadow" copy in RAM
   gpioState.gpioData = 0x1ff;
   // write the "shadow" values out to the I/O pins
   pGPIO->gpioData = gpioState.gpioData;

   // do a read of the "shadow" value and then clear the lsb
   gpioState->gpioData &= 0xFE;
   // write the new value to the I/O pins
   pGPIO->gpioData = pGpioState->gpioData;

   // ...