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nodemcu-firmware/app/driver/i2c_master.c

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/*
* ESPRESSIF MIT License
*
* Copyright (c) 2016 <ESPRESSIF SYSTEMS (SHANGHAI) PTE LTD>
*
* Permission is hereby granted for use on ESPRESSIF SYSTEMS ESP8266 only, in which case,
* it is free of charge, to any person obtaining a copy of this software and associated
* documentation files (the "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the Software is furnished
* to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all copies or
* substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*
* Rework of original driver: Natalia Sorokina <sonaux@gmail.com>, 2018
*/
#include <stdlib.h>
#include "ets_sys.h"
#include "osapi.h"
#include "gpio.h"
#include "user_interface.h"
#include "cpu_esp8266.h"
#include "pin_map.h"
#include "user_config.h"
#include "driver/i2c_master.h"
#ifndef I2C_MASTER_OLD_VERSION
/******************************************************************************
* NEW driver
* Enabled if I2C_MASTER_OLD_VERSION is not defined in user_config.h
*******************************************************************************/
// Supports multiple i2c buses
// I2C speed in range 25kHz - 550kHz (25kHz - 1MHz if CPU at 160MHz)
// If GPIO16 is used as SCL then speed is limited to 25kHz - 400kHz
// Speed is defined for every bus separately
// enable use GPIO16 (D0) pin as SCL line
#ifdef I2C_MASTER_GPIO16_ENABLE
#define IS_PIN16(n) ((n)==16)
// CPU_CYCLES_BETWEEN_DELAYS describes how much cpu cycles code runs
// between i2c_master_setDC() calls if delay is zero and i2c_master_set_DC_delay()
// is not being called. This is not exact value, but proportional with length of code.
// Increasing the value results in less delay and faster i2c clock speed.
#define CPU_CYCLES_BETWEEN_DELAYS 80
// CPU_CYCLES_GPIO16 is added to CPU_CYCLES_BETWEEN_DELAYS,
// as RTC-related IO takes much more time than standard GPIOs.
// Increasing the value results in less delay and faster i2c clock speed for GPIO16.
#define CPU_CYCLES_GPIO16 90
#else
// If GPIO16 support is not enabled, remove GPIO16-related code during compile
// and change timing constants.
#define IS_PIN16(n) (0)
#define CPU_CYCLES_BETWEEN_DELAYS 74
#endif //I2C_MASTER_GPIO16_ENABLE
#define MIN_SPEED 25000
#define MAX_NUMBER_OF_I2C NUM_I2C
typedef struct {
uint8 last_SDA;
uint8 last_SCL;
uint8 pin_SDA;
uint8 pin_SCL;
uint32 pin_SDA_SCL_mask;
uint32 pin_SDA_mask;
uint32 pin_SCL_mask;
uint32 speed;
sint16 cycles_delay;
} i2c_master_state_t;
static i2c_master_state_t *i2c[MAX_NUMBER_OF_I2C];
/******************************************************************************
* FunctionName : i2c_master_set_DC_delay
* Description : Internal used function - calculate delay for i2c_master_setDC
* Parameters : bus id
* Returns : NONE
*******************************************************************************/
LOCAL void ICACHE_FLASH_ATTR
i2c_master_set_DC_delay(uint16 id)
{
// [cpu cycles per half SCL clock period] - [cpu cycles that code takes to run]
i2c[id]->cycles_delay = system_get_cpu_freq() * 500000 / i2c[id]->speed - CPU_CYCLES_BETWEEN_DELAYS;
#ifdef I2C_MASTER_GPIO16_ENABLE
if(IS_PIN16(i2c[id]->pin_SCL)){ //if GPIO16
i2c[id]->cycles_delay -= CPU_CYCLES_GPIO16; //decrease delay
}
#endif //I2C_MASTER_GPIO16_ENABLE
if(i2c[id]->cycles_delay < 0){
i2c[id]->cycles_delay = 0;
}
}
/******************************************************************************
* FunctionName : i2c_master_wait_cpu_cycles
* Description : Internal used function - wait for given count of cpu cycles
* Parameters : sint16 cycles_delay
* Returns : NONE
*******************************************************************************/
static inline void i2c_master_wait_cpu_cycles(sint16 cycles_delay)
{
uint32 cycles_start;
uint32 cycles_curr;
// uses special 'ccount' register which is increased every CPU cycle
// to make precise delay
asm volatile("rsr %0, ccount":"=a"(cycles_start));
do{
asm volatile("rsr %0, ccount":"=a"(cycles_curr));
} while (cycles_curr - cycles_start < cycles_delay);
}
/******************************************************************************
* FunctionName : i2c_master_wait_gpio_SCL_high
* Description : Internal used function - wait until SCL line in a high state
(slave device may hold SCL line low until it is ready to proceed)
* Parameters : bus id
* Returns : NONE
*******************************************************************************/
static inline void i2c_master_wait_gpio_SCL_high(uint16 id)
{
// retrieves bitmask of all GPIOs from memory-mapped gpio register and exits if SCL bit is set
// equivalent, but slow variant:
// while(!(READ_PERI_REG(PERIPHS_GPIO_BASEADDR + GPIO_IN_ADDRESS) & i2c[id]->pin_SCL_mask)) {};
// even slower: while (!(gpio_input_get() & i2c[id]->pin_SCL_mask)) {};
asm volatile("l_wait:"
"l16ui %0, %[gpio_in_addr], 0;" //read gpio state into register %0
"memw;" //wait for read completion
"bnall %0, %[gpio_SCL_mask], l_wait;" // test if SCL bit not set
::[gpio_SCL_mask] "r" (i2c[id]->pin_SCL_mask),
[gpio_in_addr] "r" (PERIPHS_GPIO_BASEADDR + GPIO_IN_ADDRESS)
);
}
/******************************************************************************
* FunctionName : i2c_master_setDC
* Description : Internal used function -
* set i2c SDA and SCL bit value for half clock cycle
* Parameters : bus id, uint8 SDA, uint8 SCL
* Returns : NONE
*******************************************************************************/
LOCAL void ICACHE_FLASH_ATTR
i2c_master_setDC(uint16 id, uint8 SDA, uint8 SCL)
{
uint32 this_SDA_SCL_set_mask;
uint32 this_SDA_SCL_clear_mask;
i2c[id]->last_SDA = SDA;
i2c[id]->last_SCL = SCL;
if(i2c[id]->cycles_delay > 0){
i2c_master_wait_cpu_cycles(i2c[id]->cycles_delay);
}
if (IS_PIN16(i2c[id]->pin_SCL)){ //GPIO16 wired differently, it has it's own register address
WRITE_PERI_REG(RTC_GPIO_OUT, SCL); // write SCL value
if(1 == SDA){
GPIO_REG_WRITE(GPIO_OUT_W1TS_ADDRESS, i2c[id]->pin_SDA_mask); //SDA = 1
}else{
GPIO_REG_WRITE(GPIO_OUT_W1TC_ADDRESS, i2c[id]->pin_SDA_mask); // SDA = 0
}
if(1 == SCL){ //clock stretching, GPIO16 version
while(!(READ_PERI_REG(RTC_GPIO_IN_DATA) & 1)) {}; //read SCL value until SCL goes high
}else{
// dummy read operation and empty CPU cycles to maintain equal times for low and high state
READ_PERI_REG(RTC_GPIO_IN_DATA) & 1; asm volatile("nop;nop;nop;nop;");
}
}
else{
this_SDA_SCL_set_mask = (SDA << i2c[id]->pin_SDA) | (SCL << i2c[id]->pin_SCL);
this_SDA_SCL_clear_mask = i2c[id]->pin_SDA_SCL_mask ^ this_SDA_SCL_set_mask;
GPIO_REG_WRITE(GPIO_OUT_W1TC_ADDRESS, this_SDA_SCL_clear_mask);
GPIO_REG_WRITE(GPIO_OUT_W1TS_ADDRESS, this_SDA_SCL_set_mask);
if(1 == SCL) { //clock stretching
i2c_master_wait_gpio_SCL_high(id);
}else{
asm volatile("nop;nop;nop;"); // empty CPU cycles to maintain equal times for low and high state
}
}
}
/******************************************************************************
* FunctionName : i2c_master_getDC
* Description : Internal used function -
* get i2c SDA bit value
* Parameters : bus id
* Returns : uint8 - SDA bit value
*******************************************************************************/
static inline uint8 ICACHE_FLASH_ATTR
i2c_master_getDC(uint16 id)
{
return (READ_PERI_REG(PERIPHS_GPIO_BASEADDR + GPIO_IN_ADDRESS) >> i2c[id]->pin_SDA) & 1;
}
/******************************************************************************
* FunctionName : i2c_master_configured
* Description : checks if i2c bus is configured
* Parameters : bus id
* Returns : boolean value, true if configured
*******************************************************************************/
bool ICACHE_FLASH_ATTR
i2c_master_configured(uint16 id){
return !(NULL == i2c[id]);
}
/******************************************************************************
* FunctionName : i2c_master_init
* Description : initialize I2C bus to enable i2c operations
(reset state of all slave devices)
* Parameters : bus id
* Returns : NONE
*******************************************************************************/
void ICACHE_FLASH_ATTR
i2c_master_init(uint16 id)
{
uint8 i;
i2c_master_setDC(id, 1, 0);
// when SCL = 0, toggle SDA to clear up
i2c_master_setDC(id, 0, 0) ;
i2c_master_setDC(id, 1, 0) ;
// set data_cnt to max value
for (i = 0; i < 28; i++) {
i2c_master_setDC(id, 1, 0);
i2c_master_setDC(id, 1, 1);
}
// reset all
i2c_master_stop(id);
return;
}
/******************************************************************************
* FunctionName : i2c_master_setup
* Description : Initializes and configures the driver on given bus ID
* Parameters : bus id
* Returns : configured speed
*******************************************************************************/
uint32 ICACHE_FLASH_ATTR
i2c_master_setup(uint16 id, uint8 sda, uint8 scl, uint32 speed)
{
if(NULL == i2c[id]){
i2c[id] = (i2c_master_state_t*) malloc(sizeof(i2c_master_state_t));
}
if(NULL == i2c[id]){ // if malloc failed
return 0;
}
i2c[id]->last_SDA = 1; //default idle state
i2c[id]->last_SCL = 1;
i2c[id]->pin_SDA = pin_num[sda];
i2c[id]->pin_SCL = pin_num[scl];
i2c[id]->pin_SDA_mask = 1 << i2c[id]->pin_SDA;
i2c[id]->pin_SCL_mask = 1 << i2c[id]->pin_SCL;
i2c[id]->pin_SDA_SCL_mask = i2c[id]->pin_SDA_mask | i2c[id]->pin_SCL_mask;
i2c[id]->speed = speed;
i2c[id]->cycles_delay = 0;
if(i2c[id]->speed < MIN_SPEED){
i2c[id]->speed = MIN_SPEED;
}
i2c_master_set_DC_delay(id); // recalibrate clock
ETS_GPIO_INTR_DISABLE(); //disable gpio interrupts
if (IS_PIN16(i2c[id]->pin_SCL)){ //if GPIO16
CLEAR_PERI_REG_MASK(PAD_XPD_DCDC_CONF, 0x43); //disable all functions for XPD_DCDC
SET_PERI_REG_MASK(PAD_XPD_DCDC_CONF, 0x1); // select function RTC_GPIO0 for pin XPD_DCDC
CLEAR_PERI_REG_MASK(RTC_GPIO_CONF, 0x1); //mux configuration for out enable
SET_PERI_REG_MASK(RTC_GPIO_ENABLE, 0x1); //out enable
SET_PERI_REG_MASK(RTC_GPIO_OUT, 0x1); // set SCL high
}
else{
PIN_FUNC_SELECT(pin_mux[scl], pin_func[scl]);
SET_PERI_REG_MASK(PERIPHS_GPIO_BASEADDR + GPIO_PIN_ADDR(GPIO_ID_PIN(i2c[id]->pin_SCL)),
GPIO_PIN_PAD_DRIVER_SET(GPIO_PAD_DRIVER_ENABLE)); //open drain
gpio_output_set(i2c[id]->pin_SCL_mask, 0, i2c[id]->pin_SCL_mask, 0); //enable and set high
}
PIN_FUNC_SELECT(pin_mux[sda], pin_func[sda]);
SET_PERI_REG_MASK(PERIPHS_GPIO_BASEADDR + GPIO_PIN_ADDR(GPIO_ID_PIN(i2c[id]->pin_SDA)),
GPIO_PIN_PAD_DRIVER_SET(GPIO_PAD_DRIVER_ENABLE)); //open drain
gpio_output_set(i2c[id]->pin_SDA_mask, 0, i2c[id]->pin_SDA_mask, 0); //enable and set high
ETS_GPIO_INTR_ENABLE(); //enable gpio interrupts
if (! (gpio_input_get() ^ i2c[id]->pin_SCL_mask)){ //SCL is in low state, bus failure
return 0;
}
i2c_master_init(id);
if (! (gpio_input_get() ^ i2c[id]->pin_SDA_mask)){ //SDA is in low state, bus failure
return 0;
}
return i2c[id]->speed;
}
/******************************************************************************
* FunctionName : i2c_master_start
* Description : set i2c to send state
* Parameters : bus id
* Returns : NONE
*******************************************************************************/
void ICACHE_FLASH_ATTR
i2c_master_start(uint16 id)
{
i2c_master_set_DC_delay(id); // recalibrate clock
i2c_master_setDC(id, 1, i2c[id]->last_SCL);
i2c_master_setDC(id, 1, 1);
i2c_master_setDC(id, 0, 1);
}
/******************************************************************************
* FunctionName : i2c_master_stop
* Description : set i2c to stop sending state
* Parameters : bus id
* Returns : NONE
*******************************************************************************/
void ICACHE_FLASH_ATTR
i2c_master_stop(uint16 id)
{
i2c_master_setDC(id, 0, i2c[id]->last_SCL);
i2c_master_setDC(id, 0, 1);
i2c_master_setDC(id, 1, 1);
}
/******************************************************************************
* FunctionName : i2c_master_readByte
* Description : read Byte from i2c bus
* Parameters : bus id
* Returns : uint8 - readed value
*******************************************************************************/
uint8 ICACHE_FLASH_ATTR
i2c_master_readByte(uint16 id, sint16 ack)
{
uint8 retVal = 0;
uint8 k;
sint8 i;
//invert and clamp ACK to 0/1, because ACK == 1 for i2c means SDA in low state
uint8 ackLevel = (ack ? 0 : 1);
i2c_master_setDC(id, i2c[id]->last_SDA, 0);
i2c_master_setDC(id, 1, 0);
for (i = 7; i >= 0; i--) {
i2c_master_setDC(id, 1, 1);
k = i2c_master_getDC(id);
i2c_master_setDC(id, 1, 0); // unnecessary in last iteration
k <<= i;
retVal |= k;
}
// set ACK
i2c_master_setDC(id, ackLevel, 0);
i2c_master_setDC(id, ackLevel, 1);
i2c_master_setDC(id, 1, 0);
return retVal;
}
/******************************************************************************
* FunctionName : i2c_master_writeByte
* Description : write wrdata value(one byte) into i2c
* Parameters : bus id, uint8 wrdata - write value
* Returns : NONE
*******************************************************************************/
uint8 ICACHE_FLASH_ATTR
i2c_master_writeByte(uint16 id, uint8 wrdata)
{
uint8 dat;
sint8 i;
uint8 retVal;
i2c_master_setDC(id, i2c[id]->last_SDA, 0);
for (i = 7; i >= 0; i--) {
dat = (wrdata >> i) & 1;
i2c_master_setDC(id, dat, 0);
i2c_master_setDC(id, dat, 1);
}
//get ACK
i2c_master_setDC(id, 1, 0);
i2c_master_setDC(id, 1, 1);
retVal = i2c_master_getDC(id);
i2c_master_setDC(id, 1, 0);
return ! retVal;
}
#else // if defined I2C_MASTER_OLD_VERSION
/******************************************************************************
* OLD driver
* Enabled when I2C_MASTER_OLD_VERSION is defined in user_config.h
*******************************************************************************/
#define I2C_MASTER_SDA_MUX (pin_mux[sda])
#define I2C_MASTER_SCL_MUX (pin_mux[scl])
#define I2C_MASTER_SDA_GPIO (pinSDA)
#define I2C_MASTER_SCL_GPIO (pinSCL)
#define I2C_MASTER_SDA_FUNC (pin_func[sda])
#define I2C_MASTER_SCL_FUNC (pin_func[scl])
#define I2C_MASTER_SDA_HIGH_SCL_HIGH() \
gpio_output_set(1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 0, 1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 0)
#define I2C_MASTER_SDA_HIGH_SCL_LOW() \
gpio_output_set(1<<I2C_MASTER_SDA_GPIO, 1<<I2C_MASTER_SCL_GPIO, 1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 0)
#define I2C_MASTER_SDA_LOW_SCL_HIGH() \
gpio_output_set(1<<I2C_MASTER_SCL_GPIO, 1<<I2C_MASTER_SDA_GPIO, 1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 0)
#define I2C_MASTER_SDA_LOW_SCL_LOW() \
gpio_output_set(0, 1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 1<<I2C_MASTER_SDA_GPIO | 1<<I2C_MASTER_SCL_GPIO, 0)
#define i2c_master_wait os_delay_us
#define I2C_MASTER_SPEED 100000
#define I2C_MASTER_BUS_ID 0
LOCAL uint8 m_nLastSDA;
LOCAL uint8 m_nLastSCL;
LOCAL uint8 pinSDA = 2;
LOCAL uint8 pinSCL = 15;
/******************************************************************************
* FunctionName : i2c_master_setDC
* Description : Internal used function -
* set i2c SDA and SCL bit value for half clk cycle
* Parameters : uint8 SDA, uint8 SCL
* Returns : NONE
*******************************************************************************/
LOCAL void ICACHE_FLASH_ATTR
i2c_master_setDC(uint8 SDA, uint8 SCL)
{
uint8 sclLevel;
SDA &= 0x01;
SCL &= 0x01;
m_nLastSDA = SDA;
m_nLastSCL = SCL;
if ((0 == SDA) && (0 == SCL)) {
I2C_MASTER_SDA_LOW_SCL_LOW();
} else if ((0 == SDA) && (1 == SCL)) {
I2C_MASTER_SDA_LOW_SCL_HIGH();
} else if ((1 == SDA) && (0 == SCL)) {
I2C_MASTER_SDA_HIGH_SCL_LOW();
} else {
I2C_MASTER_SDA_HIGH_SCL_HIGH();
}
if(1 == SCL) {
do {
sclLevel = GPIO_INPUT_GET(GPIO_ID_PIN(I2C_MASTER_SCL_GPIO));
} while(sclLevel == 0);
}
i2c_master_wait(5);
}
/******************************************************************************
* FunctionName : i2c_master_getDC
* Description : Internal used function -
* get i2c SDA bit value
* Parameters : NONE
* Returns : uint8 - SDA bit value
*******************************************************************************/
LOCAL uint8 ICACHE_FLASH_ATTR
i2c_master_getDC()
{
uint8 sda_out;
sda_out = GPIO_INPUT_GET(GPIO_ID_PIN(I2C_MASTER_SDA_GPIO));
return sda_out;
}
/******************************************************************************
* FunctionName : i2c_master_init
* Description : initilize I2C bus to enable i2c operations
* Parameters : bus id
* Returns : NONE
*******************************************************************************/
void ICACHE_FLASH_ATTR
i2c_master_init(uint16 id)
{
uint8 i;
i2c_master_setDC(1, 0);
// when SCL = 0, toggle SDA to clear up
i2c_master_setDC(0, 0) ;
i2c_master_setDC(1, 0) ;
// set data_cnt to max value
for (i = 0; i < 28; i++) {
i2c_master_setDC(1, 0);
i2c_master_setDC(1, 1);
}
// reset all
i2c_master_stop(I2C_MASTER_BUS_ID);
return;
}
/******************************************************************************
* FunctionName : i2c_master_configured
* Description : checks if i2c bus is configured
* Parameters : bus id
* Returns : boolean value, true if configured
*******************************************************************************/
bool ICACHE_FLASH_ATTR
i2c_master_configured(uint16 id)
{
return true;
}
/******************************************************************************
* FunctionName : i2c_master_setup
* Description : config SDA and SCL gpio to open-drain output mode,
* mux and gpio num defined in i2c_master.h
* Parameters : bus id, uint8 sda, uint8 scl, uint32 speed
* Returns : configured speed
*******************************************************************************/
uint32 ICACHE_FLASH_ATTR
i2c_master_setup(uint16 id, uint8 sda, uint8 scl, uint32 speed)
{
pinSDA = pin_num[sda];
pinSCL = pin_num[scl];
ETS_GPIO_INTR_DISABLE() ;
// ETS_INTR_LOCK();
PIN_FUNC_SELECT(I2C_MASTER_SDA_MUX, I2C_MASTER_SDA_FUNC);
PIN_FUNC_SELECT(I2C_MASTER_SCL_MUX, I2C_MASTER_SCL_FUNC);
GPIO_REG_WRITE(GPIO_PIN_ADDR(GPIO_ID_PIN(I2C_MASTER_SDA_GPIO)), GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(I2C_MASTER_SDA_GPIO))) | GPIO_PIN_PAD_DRIVER_SET(GPIO_PAD_DRIVER_ENABLE)); //open drain;
GPIO_REG_WRITE(GPIO_ENABLE_ADDRESS, GPIO_REG_READ(GPIO_ENABLE_ADDRESS) | (1 << I2C_MASTER_SDA_GPIO));
GPIO_REG_WRITE(GPIO_PIN_ADDR(GPIO_ID_PIN(I2C_MASTER_SCL_GPIO)), GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(I2C_MASTER_SCL_GPIO))) | GPIO_PIN_PAD_DRIVER_SET(GPIO_PAD_DRIVER_ENABLE)); //open drain;
GPIO_REG_WRITE(GPIO_ENABLE_ADDRESS, GPIO_REG_READ(GPIO_ENABLE_ADDRESS) | (1 << I2C_MASTER_SCL_GPIO));
I2C_MASTER_SDA_HIGH_SCL_HIGH();
ETS_GPIO_INTR_ENABLE() ;
// ETS_INTR_UNLOCK();
i2c_master_init(I2C_MASTER_BUS_ID);
return I2C_MASTER_SPEED;
}
/******************************************************************************
* FunctionName : i2c_master_start
* Description : set i2c to send state
* Parameters : bus id
* Returns : NONE
*******************************************************************************/
void ICACHE_FLASH_ATTR
i2c_master_start(uint16 id)
{
i2c_master_setDC(1, m_nLastSCL);
i2c_master_setDC(1, 1);
i2c_master_setDC(0, 1);
}
/******************************************************************************
* FunctionName : i2c_master_stop
* Description : set i2c to stop sending state
* Parameters : bus id
* Returns : NONE
*******************************************************************************/
void ICACHE_FLASH_ATTR
i2c_master_stop(uint16 id)
{
i2c_master_wait(5);
i2c_master_setDC(0, m_nLastSCL);
i2c_master_setDC(0, 1);
i2c_master_setDC(1, 1);
}
/******************************************************************************
* FunctionName : i2c_master_readByte
* Description : read Byte from i2c bus
* Parameters : bus id
* Returns : uint8 - readed value
*******************************************************************************/
uint8 ICACHE_FLASH_ATTR
i2c_master_readByte(uint16 id, sint16 ack)
{
uint8 retVal = 0;
uint8 k, i;
uint8 ackLevel = (ack ? 0 : 1);
i2c_master_wait(5);
i2c_master_setDC(m_nLastSDA, 0);
for (i = 0; i < 8; i++) {
i2c_master_wait(5);
i2c_master_setDC(1, 0);
i2c_master_setDC(1, 1);
k = i2c_master_getDC();
i2c_master_wait(5);
if (i == 7) {
i2c_master_wait(3); ////
}
k <<= (7 - i);
retVal |= k;
}
i2c_master_setDC(1, 0);
// set ACK
i2c_master_setDC(m_nLastSDA, 0);
i2c_master_setDC(ackLevel, 0);
i2c_master_setDC(ackLevel, 1);
i2c_master_wait(3);
i2c_master_setDC(ackLevel, 0);
i2c_master_setDC(1, 0);
return retVal;
}
/******************************************************************************
* FunctionName : i2c_master_writeByte
* Description : write wrdata value(one byte) into i2c
* Parameters : bus id, uint8 wrdata - write value
* Returns : NONE
*******************************************************************************/
uint8 ICACHE_FLASH_ATTR
i2c_master_writeByte(uint16 id, uint8 wrdata)
{
uint8 dat;
sint8 i;
uint8 retVal;
i2c_master_wait(5);
i2c_master_setDC(m_nLastSDA, 0);
for (i = 7; i >= 0; i--) {
dat = wrdata >> i;
i2c_master_setDC(dat, 0);
i2c_master_setDC(dat, 1);
if (i == 0) {
i2c_master_wait(3); ////
}
i2c_master_setDC(dat, 0);
}
// get ACK
i2c_master_setDC(m_nLastSDA, 0);
i2c_master_setDC(1, 0);
i2c_master_setDC(1, 1);
retVal = i2c_master_getDC();
i2c_master_wait(5);
i2c_master_setDC(1, 0);
return ! retVal;
}
#endif
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