4a1b600be4
Look-up tables were used for determining the delay loop counts before. Based on these hand-tuned values, the loop overhead was estimated for each option -- 80 and 160 MHz, fast and slow GPIO access. Instead of the great number of tunable parameters one now only has to tune the overhead values if the code is changed. Functions were added to the API which allow setting an arbitrary frequency. API backward compatibility is retained. i2c: fix potential overflow situation
199 lines
5.6 KiB
C
199 lines
5.6 KiB
C
/*
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* The MIT License (MIT)
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*
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* Copyright (c) 2015 Johan Kanflo (github.com/kanflo)
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*
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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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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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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
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* THE SOFTWARE.
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*/
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/**
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* I2C driver for ESP8266 written for use with esp-open-rtos
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* Based on https://en.wikipedia.org/wiki/I²C#Example_of_bit-banging_the_I.C2.B2C_Master_protocol
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*/
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#ifndef __I2C_H__
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#define __I2C_H__
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#include <stdint.h>
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#include <stdbool.h>
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#include <errno.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* Define i2c bus max number
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*/
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#ifndef I2C_MAX_BUS
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#define I2C_MAX_BUS 2
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#endif
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/* Set this to 1 if you intend to use GPIO 16 for I2C. It is not recommended
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* and will result in degradation of performance and timing accuracy.
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*/
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#ifndef I2C_USE_GPIO16
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#define I2C_USE_GPIO16 0
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#endif
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#define I2C_DEFAULT_CLK_STRETCH (10)
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/* SCL speed settings. 160 MHz sysclk frequency will result in improved
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* timing accuracy. Greater bitrates will have poorer accuracy. 1000K is the
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* maximum SCL speed at 80 MHz sysclk.
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*/
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typedef enum
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{
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I2C_FREQ_80K = 0,
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I2C_FREQ_100K,
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I2C_FREQ_400K,
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I2C_FREQ_500K,
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I2C_FREQ_600K,
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I2C_FREQ_800K,
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I2C_FREQ_1000K,
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I2C_FREQ_1300K
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} i2c_freq_t;
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/**
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* Device descriptor
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*/
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typedef struct i2c_dev
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{
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uint8_t bus;
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uint8_t addr;
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} i2c_dev_t;
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/// Level 0 API
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/**
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* Init bitbanging I2C driver on given pins
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* @param bus Bus i2c selection
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* @param scl_pin SCL pin for I2C
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* @param sda_pin SDA pin for I2C
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* @param freq frequency of bus (ex : I2C_FREQ_400K)
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* @param clk_stretch I2C clock stretch. I2C_DEFAULT_CLK_STRETCH would be good in most cases
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* @return Non-zero if error occured
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*/
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int i2c_init(uint8_t bus, uint8_t scl_pin, uint8_t sda_pin, i2c_freq_t freq);
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/**
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* Init bitbanging I2C driver on given pins
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* @param bus Bus i2c selection
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* @param scl_pin SCL pin for I2C
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* @param sda_pin SDA pin for I2C
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* @param freq frequency of bus in hertz
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* @param clk_stretch I2C clock stretch. I2C_DEFAULT_CLK_STRETCH would be good in most cases
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* @return Non-zero if error occured
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*/
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int i2c_init_hz(uint8_t bus, uint8_t scl_pin, uint8_t sda_pin, uint32_t freq);
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/**
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* Change bus frequency
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* @param bus Bus i2c selection
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* @param freq frequency of bus (ex : I2C_FREQ_400K)
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*/
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int i2c_set_frequency(uint8_t bus, i2c_freq_t freq);
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/**
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* Change bus frequency
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* @param bus Bus i2c selection
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* @param freq frequency of bus in hertz
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*/
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int i2c_set_frequency_hz(uint8_t bus, uint32_t freq);
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/**
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* Change clock stretch
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* @param bus I2C bus
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* @param clk_stretch I2C clock stretch. I2C_DEFAULT_CLK_STRETCH by default
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*/
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void i2c_set_clock_stretch(uint8_t bus, uint32_t clk_stretch);
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/**
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* Write a byte to I2C bus.
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* @param bus Bus i2c selection
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* @param byte Pointer to device descriptor
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* @return true if slave acked
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*/
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bool i2c_write(uint8_t bus, uint8_t byte);
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/**
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* Read a byte from I2C bus.
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* @param bus Bus i2c selection
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* @param ack Set Ack for slave (false: Ack // true: NoAck)
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* @return byte read from slave.
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*/
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uint8_t i2c_read(uint8_t bus, bool ack);
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/**
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* Send start or restart condition
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* @param bus Bus i2c selection
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*/
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void i2c_start(uint8_t bus);
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/**
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* Send stop condition
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* @param bus Bus i2c selection
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* @return false if link was broken
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*/
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bool i2c_stop(uint8_t bus);
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/**
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* get status from I2C bus.
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* @param bus Bus i2c selection
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* @return true if busy.
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*/
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bool i2c_status(uint8_t bus);
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/// Level 1 API (Don't need functions above)
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/**
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* This function will allow you to force a transmission I2C, cancel current transmission.
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* Warning: Use with precaution. Don't use it if you can avoid it. Usefull for priority transmission.
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* @param bus Bus i2c selection
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* @param state Force the next I2C transmission if true (Use with precaution)
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*/
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void i2c_force_bus(uint8_t bus, bool state);
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/**
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* Write 'len' bytes from 'buf' to slave at 'data' register adress .
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* @param bus Bus i2c selection
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* @param slave_addr slave device address
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* @param data Pointer to register address to send if non-null
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* @param buf Pointer to data buffer
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* @param len Number of byte to send
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* @return Non-Zero if error occured
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*/
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int i2c_slave_write(uint8_t bus, uint8_t slave_addr, const uint8_t *data, const uint8_t *buf, uint32_t len);
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/**
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* Issue a send operation of 'data' register adress, followed by reading 'len' bytes
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* from slave into 'buf'.
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* @param bus Bus i2c selection
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* @param slave_addr slave device address
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* @param data Pointer to register address to send if non-null
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* @param buf Pointer to data buffer
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* @param len Number of byte to read
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* @return Non-Zero if error occured
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*/
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int i2c_slave_read(uint8_t bus, uint8_t slave_addr, const uint8_t *data, uint8_t *buf, uint32_t len);
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#ifdef __cplusplus
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}
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#endif
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#endif /* __I2C_H__ */
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