Hardware Reference
In-Depth Information
42 map = (char
) mmap(
43 NULL, /
∗
Any address
/
∗
∗
44 BLOCK_SIZE, /
# of bytes
/
∗
∗
45 PROT_READ| PROT_WRITE,
46 MAP_SHARED, /
Shared
/
∗
∗
47 fd, /
/dev/mem
/
∗
∗
48 GPIO_BASE /
Offset to GPIO
/
∗
∗
49 );
50
51 if ( (long)map == 1L ) {
52 perror("mmap(/dev/mem)");
53 exit(1);
54 }
55
56 close(fd);
57 ugpio = (volatile unsigned
)map;
∗
58 }
59
60 /
∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗
61
Configure GPIO as Input or Output
∗
62
/
∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗
63 static inline void
64 gpio_config (int gpio, direction_t output) {
65 INP_GPIO (gpio);
66 if ( output ) {
67 OUT_GPIO(gpio);
68 }
69 }
70
71 /
∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗
72
Write a bit to the GPIO pin
∗
73
/
∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗
74 static inline void
75 gpio_write(int gpio, int bit) {
76 unsigned sel = 1 << gpio;
77
78 if ( bit ) {
79 GPIO_SET = sel;
80 } else {
81 GPIO_CLR = sel;
82 }
83 }
84
85 /
∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗
86
Read a bit from a GPIO pin
∗
87
/
∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗
88 static inline int
