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gpio.cc
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gpio.cc
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/* Copyright (C) 2015 Goswin von Brederlow <goswin-v-b@web.de>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
* GPIO helper for the Raspberry Pi
*/
#include "gpio.h"
#include "peripherals.h"
#include "delay.h"
namespace GPIO {
enum {
// function selector
GPIO_FSEL0 = 0x00, // 0x3F200000
GPIO_FSEL1 = 0x04, // 0x3F200004
GPIO_FSEL2 = 0x08, // 0x3F200008
GPIO_FSEL3 = 0x0C, // 0x3F20000C
GPIO_FSEL4 = 0x10, // 0x3F200010
GPIO_FSEL5 = 0x14, // 0x3F200014
// set and clear pin output
GPIO_SET0 = 0x1C, // 0x3F20001C
GPIO_SET1 = 0x20, // 0x3F200020
GPIO_CLR0 = 0x28, // 0x3F200028
GPIO_CLR1 = 0x2C, // 0x3F20002C
// Controls actuation of pull up/down to ALL GPIO pins.
GPIO_PUD = 0x94, // 0x3F200094
// Controls actuation of pull up/down for specific GPIO pin.
GPIO_PUDCLK0 = 0x98, // 0x3F200098
GPIO_PUDCLK1 = 0x9C, // 0x3F20009C
};
constexpr volatile uint32_t * reg(uint32_t offset) {
return Peripherals::reg(GPIO::GPIO_BASE + offset);
}
void set_function(uint32_t pin, FSel fn) {
volatile uint32_t *fsel = ®(GPIO_FSEL0)[pin / 10];
uint32_t shift = (pin % 10) * 3;
uint32_t mask = ~(7 << shift);
*fsel = (*fsel & mask) | (fn << shift);
}
void set(uint32_t pin, bool state) {
// set or clear bit for pin
reg(state ? GPIO_SET0 : GPIO_CLR0)[pin / 32] = 1 << (pin % 32);
}
void set_pull_up_down(uint32_t pin, PullUpDown action) {
// set action & delay for 150 cycles.
volatile uint32_t *pud = reg(GPIO_PUD);
*pud = action;
delay(150);
// trigger action & delay for 150 cycles.
volatile uint32_t *clock =
reg((pin < 32) ? GPIO_PUDCLK0 : GPIO_PUDCLK1);
*clock = (1 << (pin % 32));
delay(150);
// clear action
*pud = OFF;
// remove clock
*clock = 0;
}
}