diff options
Diffstat (limited to 'software/demo_gpio')
| -rw-r--r-- | software/demo_gpio/demo_gpio.c | 54 |
1 files changed, 32 insertions, 22 deletions
diff --git a/software/demo_gpio/demo_gpio.c b/software/demo_gpio/demo_gpio.c index dec91b5..00bc8cd 100644 --- a/software/demo_gpio/demo_gpio.c +++ b/software/demo_gpio/demo_gpio.c @@ -7,6 +7,7 @@ #include "plic_driver.h" #include "encoding.h" #include <unistd.h> +#include "stdatomic.h" #define RTC_FREQUENCY 32768 @@ -25,12 +26,6 @@ function_ptr_t g_ext_interrupt_handlers[PLIC_NUM_INTERRUPTS]; plic_instance_t g_plic; -// Simple variables for LEDs, buttons, etc. -volatile unsigned int* g_output_vals = (unsigned int *) (GPIO_BASE_ADDR + GPIO_OUTPUT_VAL); -volatile unsigned int* g_input_vals = (unsigned int *) (GPIO_BASE_ADDR + GPIO_INPUT_VAL); -volatile unsigned int* g_output_en = (unsigned int *) (GPIO_BASE_ADDR + GPIO_OUTPUT_EN); -volatile unsigned int* g_pullup_en = (unsigned int *) (GPIO_BASE_ADDR + GPIO_PULLUP_EN); -volatile unsigned int* g_input_en = (unsigned int *) (GPIO_BASE_ADDR + GPIO_INPUT_EN); /*Entry Point for PLIC Interrupt Handler*/ void handle_m_ext_interrupt(){ @@ -60,12 +55,12 @@ void handle_m_time_interrupt(){ *mtimecmp = then; // read the current value of the LEDS and invert them. - uint32_t leds = *g_output_vals; - - *g_output_vals ^= ((0x1 << RED_LED_OFFSET) | - (0x1 << GREEN_LED_OFFSET) | - (0x1 << BLUE_LED_OFFSET)); + uint32_t leds = GPIO_REG(GPIO_OUTPUT_VAL); + GPIO_REG(GPIO_OUTPUT_VAL) ^= ((0x1 << RED_LED_OFFSET) | + (0x1 << GREEN_LED_OFFSET) | + (0x1 << BLUE_LED_OFFSET)); + // Re-enable the timer interrupt. set_csr(mie, MIP_MTIP); @@ -101,6 +96,8 @@ const char * instructions_msg = " \ SiFive E-Series Software Development Kit 'demo_gpio' program.\n\ Every 1.5 second, the Timer Interrupt will invert the LEDs.\n\ (Arty Dev Kit Only): Press Buttons 0, 1, 2 to Set the LEDs.\n\ +Pin 19 (HiFive1) or A5 (Arty Dev Kit) is being bit-banged\n\ +for GPIO speed demonstration.\n\ \n\ "; @@ -114,7 +111,7 @@ void print_instructions() { void button_0_handler(void) { // Red LED on - * g_output_vals |= (0x1 << RED_LED_OFFSET); + GPIO_REG(GPIO_OUTPUT_VAL) |= (0x1 << RED_LED_OFFSET); // Clear the GPIO Pending interrupt by writing 1. GPIO_REG(GPIO_RISE_IP) = (0x1 << BUTTON_0_OFFSET); @@ -124,7 +121,7 @@ void button_0_handler(void) { void button_1_handler(void) { // Green LED On - * g_output_vals |= (1 << GREEN_LED_OFFSET); + GPIO_REG(GPIO_OUTPUT_VAL) |= (1 << GREEN_LED_OFFSET); // Clear the GPIO Pending interrupt by writing 1. GPIO_REG(GPIO_RISE_IP) = (0x1 << BUTTON_1_OFFSET); @@ -135,7 +132,7 @@ void button_1_handler(void) { void button_2_handler(void) { // Blue LED On - * g_output_vals |= (1 << BLUE_LED_OFFSET); + GPIO_REG(GPIO_OUTPUT_VAL) |= (1 << BLUE_LED_OFFSET); GPIO_REG(GPIO_RISE_IP) = (0x1 << BUTTON_2_OFFSET); @@ -204,16 +201,19 @@ int main(int argc, char **argv) // can be used as both Inputs and Outputs. #ifdef HAS_BOARD_BUTTONS - * g_output_en &= ~((0x1 << BUTTON_0_OFFSET) | (0x1 << BUTTON_1_OFFSET) | (0x1 << BUTTON_2_OFFSET)); - * g_pullup_en &= ~((0x1 << BUTTON_0_OFFSET) | (0x1 << BUTTON_1_OFFSET) | (0x1 << BUTTON_2_OFFSET)); - * g_input_en |= ((0x1 << BUTTON_0_OFFSET) | (0x1 << BUTTON_1_OFFSET) | (0x1 << BUTTON_2_OFFSET)); + GPIO_REG(GPIO_OUTPUT_EN) &= ~((0x1 << BUTTON_0_OFFSET) | (0x1 << BUTTON_1_OFFSET) | (0x1 << BUTTON_2_OFFSET)); + GPIO_REG(GPIO_PULLUP_EN) &= ~((0x1 << BUTTON_0_OFFSET) | (0x1 << BUTTON_1_OFFSET) | (0x1 << BUTTON_2_OFFSET)); + GPIO_REG(GPIO_INPUT_EN) |= ((0x1 << BUTTON_0_OFFSET) | (0x1 << BUTTON_1_OFFSET) | (0x1 << BUTTON_2_OFFSET)); #endif - * g_input_en &= ~((0x1<< RED_LED_OFFSET) | (0x1<< GREEN_LED_OFFSET) | (0x1 << BLUE_LED_OFFSET)) ; - * g_output_en |= ((0x1<< RED_LED_OFFSET)| (0x1<< GREEN_LED_OFFSET) | (0x1 << BLUE_LED_OFFSET)) ; - * g_output_vals |= (0x1 << BLUE_LED_OFFSET) ; - * g_output_vals &= ~((0x1<< RED_LED_OFFSET) | (0x1<< GREEN_LED_OFFSET)) ; + GPIO_REG(GPIO_INPUT_EN) &= ~((0x1<< RED_LED_OFFSET) | (0x1<< GREEN_LED_OFFSET) | (0x1 << BLUE_LED_OFFSET)) ; + GPIO_REG(GPIO_OUTPUT_EN) |= ((0x1<< RED_LED_OFFSET)| (0x1<< GREEN_LED_OFFSET) | (0x1 << BLUE_LED_OFFSET)) ; + GPIO_REG(GPIO_OUTPUT_VAL) |= (0x1 << BLUE_LED_OFFSET) ; + GPIO_REG(GPIO_OUTPUT_VAL) &= ~((0x1<< RED_LED_OFFSET) | (0x1<< GREEN_LED_OFFSET)) ; + // For Bit-banging with Atomics demo. + GPIO_REG(GPIO_OUTPUT_EN) |= (0x1 << PIN_19_OFFSET); + /************************************************************************** * Set up the PLIC * @@ -225,7 +225,17 @@ int main(int argc, char **argv) reset_demo(); - while (1); + /************************************************************************** + * Demonstrate fast GPIO bit-banging. + * One can bang it faster than this if you know + * the entire OUTPUT_VAL that you want to write, but + * Atomics give a quick way to control a single bit. + *************************************************************************/ + uint32_t mask = (1 << PIN_19_OFFSET); + + while (1){ + atomic_fetch_xor_explicit(&GPIO_REG(GPIO_OUTPUT_VAL), mask, memory_order_relaxed); + } return 0; |