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rt-thread-official/bsp/apollo2/board/smbus.c

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/*
* File : smbus.c
* This file is part of RT-Thread RTOS
* COPYRIGHT (C) 2006 - 2017, RT-Thread Development Team
*
* 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 2 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.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Change Logs:
* Date Author Notes
* 2017-12-04 Haley the first version
*/
#include <rtthread.h>
#include <rtdevice.h>
#include "am_mcu_apollo.h"
#ifdef RT_USING_SMBUS
#define SMBUS_GPIO_SDA 5
#define SMBUS_GPIO_SCL 6
#define mSDA_LOW() am_hal_gpio_out_bit_clear(SMBUS_GPIO_SDA) /* Clear SDA line */
#define mSDA_HIGH() am_hal_gpio_out_bit_set(SMBUS_GPIO_SDA) /* Set SDA line */
#define mSCL_LOW() am_hal_gpio_out_bit_clear(SMBUS_GPIO_SCL) /* Clear SCL line */
#define mSCL_HIGH() am_hal_gpio_out_bit_set(SMBUS_GPIO_SCL) /* Set SCL line */
#define mSDA_READ() am_hal_gpio_input_bit_read(SMBUS_GPIO_SDA) /* Read SDA line */
#define mSDA_IN() am_hal_gpio_pin_config(SMBUS_GPIO_SDA, AM_HAL_GPIO_INPUT | AM_HAL_GPIO_PULL6K) /* Set SDA as Input */
#define mSDA_OUT() am_hal_gpio_pin_config(SMBUS_GPIO_SDA, AM_HAL_GPIO_OUTPUT) /* Set SDA as Output */
#define mSCL_OUT() am_hal_gpio_pin_config(SMBUS_GPIO_SCL, AM_HAL_GPIO_OUTPUT) /* Set SCL as Output */
#define ACK 0
#define NACK 1
/* SCL keep time */
static void keep_delay(void)
{
int i;
for(i = 0; i < 30; i++)
__nop();
}
static void few_delay(void)
{
__nop();
__nop();
}
static rt_uint8_t am_smbus_send_bit(rt_uint8_t send_bit)
{
mSDA_OUT();
few_delay();
if(send_bit) /* Send a bit */
mSDA_HIGH();
else
mSDA_LOW();
mSCL_HIGH(); /* High Level of Clock Pulse */
keep_delay();
mSCL_LOW();
keep_delay();
return 0;
}
static rt_uint8_t am_smbus_read_bit(void)
{
rt_uint8_t read_bit;
mSDA_IN();
few_delay();
mSCL_HIGH(); /* High Level of Clock Pulse */
keep_delay();
read_bit = mSDA_READ(); /* Read a bit, save it in Read_bit */
mSCL_LOW();
keep_delay();
return read_bit;
}
static void am_smbus_start_bit(void)
{
mSDA_OUT();
mSDA_HIGH(); /* Generate bus free time between Stop */
keep_delay();
mSCL_HIGH();
keep_delay();
mSDA_LOW(); /* Hold time after (Repeated) Start */
keep_delay();
mSCL_LOW();
keep_delay();
}
static void am_smbus_stop_bit(void)
{
mSDA_OUT();
mSDA_HIGH(); /* Generate bus free time between Stop */
keep_delay();
mSCL_LOW();
keep_delay();
mSDA_LOW(); /* Hold time after Stop */
keep_delay();
mSCL_HIGH(); /* For sleep mode(SCL needs to be high during Sleep.) */
keep_delay();
}
static rt_uint8_t am_smbus_tx_byte(rt_uint8_t tx_byte)
{
int i;
rt_uint8_t ack_bit;
rt_uint8_t bit_out;
for(i = 0; i < 8; i++)
{
if(tx_byte&0x80)
bit_out = 1; /* If the current bit of Tx_buffer is 1 set bit_out */
else
bit_out = 0; /* else clear bit_out */
am_smbus_send_bit(bit_out); /* Send the current bit on SDA */
tx_byte <<= 1; /* Get next bit for checking */
}
ack_bit = am_smbus_read_bit(); /* Get acknowledgment bit */
return ack_bit;
}
static rt_uint8_t am_smbus_rx_byte(rt_uint8_t ack_nack)
{
int i;
rt_uint8_t rx_byte;
for(i = 0; i < 8; i++)
{
if(am_smbus_read_bit()) /* Get a bit from the SDA line */
{
rx_byte <<= 1; /* If the bit is HIGH save 1 in RX_buffer */
rx_byte |=0x01;
}
else
{
rx_byte <<= 1; /* If the bit is LOW save 0 in RX_buffer */
rx_byte &=0xfe;
}
}
am_smbus_send_bit(ack_nack); /* Sends acknowledgment bit */
return rx_byte;
}
rt_uint8_t am_smbus_tx_then_tx(rt_uint8_t SlaveAddress, rt_uint8_t command, rt_uint8_t* pBuffer, rt_uint16_t bytesNumber)
{
int i;
am_smbus_start_bit(); /* Start condition */
if(am_smbus_tx_byte(SlaveAddress)) /* Send SlaveAddress and write */
return 1;
if(am_smbus_tx_byte(command)) /* Send command */
return 1;
for(i = 0; i < bytesNumber; i++)
{
am_smbus_tx_byte(pBuffer[i]); /* Write data, slave must send ACK */
}
am_smbus_stop_bit(); /* Stop condition */
return 0;
}
rt_uint8_t am_smbus_tx_then_rx(rt_uint8_t SlaveAddress, rt_uint8_t command, rt_uint8_t* pBuffer, rt_uint16_t bytesNumber)
{
int i;
am_smbus_start_bit(); /* Start condition */
if(am_smbus_tx_byte(SlaveAddress)) /* Send SlaveAddress and write */
return 1;
if(am_smbus_tx_byte(command)) /* Send command */
return 1;
am_smbus_start_bit(); /* Repeated Start condition */
if(am_smbus_tx_byte(SlaveAddress | 0x01)) /* Send SlaveAddress and read */
return 1;
for(i = 0; i < bytesNumber; i++)
{
pBuffer[i] = am_smbus_rx_byte(ACK); /* Read data, master must send ACK */
}
am_smbus_stop_bit(); /* Stop condition */
return 0;
}
void am_smbus_scl_high(void)
{
mSCL_HIGH(); /* For sleep mode(SCL needs to be high during Sleep.) */
keep_delay();
}
void am_smbus_scl_low(void)
{
mSCL_LOW(); /* For sleep mode(SCL needs to be high during Sleep.) */
keep_delay();
}
int rt_hw_smbus_init(void)
{
mSDA_OUT();
mSCL_OUT();
mSDA_HIGH(); /* bus free */
mSCL_HIGH();
return 0;
}
#ifdef RT_USING_COMPONENTS_INIT
INIT_BOARD_EXPORT(rt_hw_smbus_init);
#endif
#endif
/*@}*/
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