gpio.c

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/** @addtogroup gpio_file
 
@brief <b>libopencm3 STM32F1xx General Purpose I/O</b>
 
@version 1.0.0
 
@author @htmlonly &copy; @endhtmlonly 2009
Uwe Hermann <uwe@hermann-uwe.de>
@author @htmlonly &copy; @endhtmlonly 2012
Ken Sarkies <ksarkies@internode.on.net>
 
@date 18 August 2012
 
Each I/O port has 16 individually configurable bits. Many I/O pins share GPIO
functionality with a number of alternate functions and must be configured to
the alternate function mode if these are to be accessed. A feature is available
to remap alternative functions to a limited set of alternative pins in the
event of a clash of requirements.
 
The data registers associated with each port for input and output are 32 bit
with the upper 16 bits unused. The output buffer must be written as a 32 bit
word, but individual bits may be set or reset separately in atomic operations
to avoid race conditions during interrupts. Bits may also be individually
locked to prevent accidental configuration changes. Once locked the
configuration cannot be changed until after the next reset.
 
Each port bit can be configured as analog or digital input, the latter can be
floating or pulled up or down. As outputs they can be configured as either
push-pull or open drain, digital I/O or alternate function, and with maximum
output speeds of 2MHz, 10MHz, or 50MHz.
 
On reset all ports are configured as digital floating input.
 
@section gpio_api_ex Basic GPIO Handling API.
 
Example 1: Push-pull digital output actions on ports C2 and C9
 
@code
        gpio_set_mode(GPIOC, GPIO_MODE_OUTPUT_2_MHZ,
                      GPIO_CNF_OUTPUT_PUSHPULL,  GPIO2 | GPIO9);
        gpio_set(GPIOC, GPIO2 | GPIO9);
        gpio_clear(GPIOC, GPIO2);
        gpio_toggle(GPIOC, GPIO2 | GPIO9);
        gpio_port_write(GPIOC, 0x204);
@endcode
 
Example 1: Digital input on port C12
 
@code
        gpio_set_mode(GPIOC, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO12);
        reg16 = gpio_port_read(GPIOC);
@endcode
 
LGPL License Terms @ref lgpl_license
*/
/*
 * This file is part of the libopencm3 project.
 *
 * Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
 *
 * This library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This library 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#include <libopencm3/stm32/gpio.h>
 
/**@{*/
 
/*---------------------------------------------------------------------------*/
/** @brief Set GPIO Pin Mode
 
Sets the mode (input/output) and configuration (analog/digitial and
open drain/push pull), for a set of GPIO pins on a given GPIO port.
 
@param[in] gpioport Unsigned int32. Port identifier @ref gpio_port_id
@param[in] mode Unsigned int8. Pin mode @ref gpio_mode
@param[in] cnf Unsigned int8. Pin configuration @ref gpio_cnf
@param[in] gpios Unsigned int16. Pin identifiers @ref gpio_pin_id
             If multiple pins are to be set, use bitwise OR '|' to separate
             them.
*/
 
void gpio_set_mode(uint32_t gpioport, uint8_t mode, uint8_t cnf, uint16_t gpios)
{
        uint16_t i, offset = 0;
        uint32_t crl = 0, crh = 0, tmp32 = 0;
 
        /*
         * We want to set the config only for the pins mentioned in gpios,
         * but keeping the others, so read out the actual config first.
         */
        crl = GPIO_CRL(gpioport);
        crh = GPIO_CRH(gpioport);
 
        /* Iterate over all bits, use i as the bitnumber. */
        for (i = 0; i < 16; i++) {
                /* Only set the config if the bit is set in gpios. */
                if (!((1 << i) & gpios)) {
                        continue;
                }
 
                /* Calculate bit offset. */
                offset = (i < 8) ? (i * 4) : ((i - 8) * 4);
 
                /* Use tmp32 to either modify crl or crh. */
                tmp32 = (i < 8) ? crl : crh;
 
                /* Modify bits are needed. */
                tmp32 &= ~(0xf << offset);      /* Clear the bits first. */
                tmp32 |= (mode << offset) | (cnf << (offset + 2));
 
                /* Write tmp32 into crl or crh, leave the other unchanged. */
                crl = (i < 8) ? tmp32 : crl;
                crh = (i >= 8) ? tmp32 : crh;
        }
 
        GPIO_CRL(gpioport) = crl;
        GPIO_CRH(gpioport) = crh;
}
 
/*---------------------------------------------------------------------------*/
/** @brief Map the EVENTOUT signal
 
Enable the EVENTOUT signal and select the port and pin to be used.
 
@param[in] evoutport Unsigned int8. Port for EVENTOUT signal @ref afio_evcr_port
@param[in] evoutpin Unsigned int8. Pin for EVENTOUT signal @ref afio_evcr_pin
*/
void gpio_set_eventout(uint8_t evoutport, uint8_t evoutpin)
{
        AFIO_EVCR = AFIO_EVCR_EVOE | evoutport | evoutpin;
}
 
/*---------------------------------------------------------------------------*/
/** @brief Map Alternate Function Port Bits (Main Set)
 
A number of alternate function ports can be remapped to defined alternative
port bits to avoid clashes in cases where multiple alternate functions are
present.  Refer to the datasheets for the particular mapping desired. This
provides the main set of remap functionality. See @ref gpio_secondary_remap for
a number of lesser used remaps.
 
The AFIO remapping feature is used only with the STM32F10x series.
 
@note The Serial Wire JTAG disable controls allow certain GPIO ports to become
available in place of some of the SWJ signals. Full SWJ capability is obtained
by setting this to zero. The value of this must be specified for every call to
this function as its current value cannot be ascertained from the hardware.
 
@param[in] swjdisable Disable parts of the SWJ capability @ref
afio_swj_disable.
@param[in] maps Bitwise OR of map enable controls you wish to
enable from @ref afio_remap, @ref afio_remap_can1, @ref afio_remap_tim3,
@ref afio_remap_tim2, @ref afio_remap_tim1, @ref afio_remap_usart3. For
connectivity line devices only @ref afio_remap_cld are also available.
*/
void gpio_primary_remap(uint32_t swjdisable, uint32_t maps)
{
        /*
         * the SWJ_CFG bits are write only.  (read is explicitly undefined)
         * To be sure we set only the bits we want we must clear them first.
         * However, we are still trying to only enable the map bits desired.
         */
        uint32_t reg = AFIO_MAPR & ~AFIO_MAPR_SWJ_MASK;
        AFIO_MAPR = reg | swjdisable | maps;
}
 
/*---------------------------------------------------------------------------*/
/** @brief Map Alternate Function Port Bits (Secondary Set)
 
A number of alternate function ports can be remapped to defined alternative
port bits to avoid clashes in cases where multiple alternate functions are
present.  Refer to the datasheets for the particular mapping desired. This
provides the second smaller and less used set of remap functionality. See @ref
gpio_primary_remap for the main set of remaps.
 
The AFIO remapping feature is used only with the STM32F10x series.
 
@param[in] maps Unsigned int32. Bitwise OR of map enable controls from @ref
afio_remap2
*/
void gpio_secondary_remap(uint32_t maps)
{
        AFIO_MAPR2 |= maps;
}
 
/**@}*/