102 lines
3.3 KiB
C
102 lines
3.3 KiB
C
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// Copyright (c) 2014 Adafruit Industries
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// Author: Tony DiCola
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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// Simple fast memory-mapped GPIO library for the Beaglebone Black.
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// Allows reading and writing GPIO at very high speeds, up to ~2.6mhz!
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/*
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// Example usage:
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#include <stdio.h>
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#include "bbb_mmio.h"
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int main(int argc, char* argv[]) {
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// Get GPIO pin.
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// See the giant table of of pins in the system reference manual for details
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// on the base and number for a given GPIO:
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// https://github.com/CircuitCo/BeagleBone-Black/blob/master/BBB_SRM.pdf?raw=true
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// Section 7 Connectors, table 12 shows P8_11 maps to GPIO1_13, so 1 is the
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// gpio base and 13 is the gpio number.
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gpio_t p8_11;
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if (bbb_mmio_get_gpio(1, 13, &p8_11) < 0) {
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printf("Couldn't get requested GPIO pin!\n");
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return 1;
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}
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// Set pin as output.
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bbb_mmio_set_output(p8_11);
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// Toggle the pin high and low as fast as possible.
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// This generates a signal at about 2.6mhz in my tests.
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// Each pulse high/low is only about 200 nanoseconds long!
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while (1) {
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bbb_mmio_set_high(p8_11);
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bbb_mmio_set_low(p8_11);
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}
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return 0;
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}
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*/
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#ifndef BBB_MMIO_H
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#define BBB_MMIO_H
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#include <stdint.h>
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#define MMIO_SUCCESS 0
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#define MMIO_ERROR_ARGUMENT -1
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#define MMIO_ERROR_DEVMEM -2
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#define MMIO_ERROR_MMAP -3
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#define MMIO_OE_ADDR 0x134
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#define MMIO_GPIO_DATAOUT 0x13C
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#define MMIO_GPIO_DATAIN 0x138
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#define MMIO_GPIO_CLEARDATAOUT 0x190
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#define MMIO_GPIO_SETDATAOUT 0x194
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// Define struct to represent a GPIO pin based on its base memory address and number.
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typedef struct {
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volatile uint32_t* base;
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int number;
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} gpio_t;
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int bbb_mmio_get_gpio(int base, int number, gpio_t* gpio);
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static inline void bbb_mmio_set_output(gpio_t gpio) {
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gpio.base[MMIO_OE_ADDR/4] &= (0xFFFFFFFF ^ (1 << gpio.number));
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}
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static inline void bbb_mmio_set_input(gpio_t gpio) {
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gpio.base[MMIO_OE_ADDR/4] |= (1 << gpio.number);
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}
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static inline void bbb_mmio_set_high(gpio_t gpio) {
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gpio.base[MMIO_GPIO_SETDATAOUT/4] = 1 << gpio.number;
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}
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static inline void bbb_mmio_set_low(gpio_t gpio) {
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gpio.base[MMIO_GPIO_CLEARDATAOUT/4] = 1 << gpio.number;
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}
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static inline uint32_t bbb_mmio_input(gpio_t gpio) {
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return gpio.base[MMIO_GPIO_DATAIN/4] & (1 << gpio.number);
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}
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#endif
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