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circuitpython/extmod/machine_i2c.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2016 Damien P. George
*
* Permission is hereby granted, 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.
*/
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include "py/mphal.h"
#include "py/runtime.h"
#include "extmod/machine_i2c.h"
#if MICROPY_PY_MACHINE_I2C
typedef struct _machine_i2c_obj_t {
mp_obj_base_t base;
uint32_t us_delay;
uint32_t us_timeout;
mp_hal_pin_obj_t scl;
mp_hal_pin_obj_t sda;
} machine_i2c_obj_t;
STATIC void mp_hal_i2c_delay(machine_i2c_obj_t *self) {
// We need to use an accurate delay to get acceptable I2C
// speeds (eg 1us should be not much more than 1us).
mp_hal_delay_us_fast(self->us_delay);
}
STATIC void mp_hal_i2c_scl_low(machine_i2c_obj_t *self) {
mp_hal_pin_od_low(self->scl);
}
STATIC int mp_hal_i2c_scl_release(machine_i2c_obj_t *self) {
uint32_t count = self->us_timeout;
mp_hal_pin_od_high(self->scl);
mp_hal_i2c_delay(self);
// For clock stretching, wait for the SCL pin to be released, with timeout.
for (; mp_hal_pin_read(self->scl) == 0 && count; --count) {
mp_hal_delay_us_fast(1);
}
return count != 0;
}
STATIC void mp_hal_i2c_sda_low(machine_i2c_obj_t *self) {
mp_hal_pin_od_low(self->sda);
}
STATIC void mp_hal_i2c_sda_release(machine_i2c_obj_t *self) {
mp_hal_pin_od_high(self->sda);
}
STATIC int mp_hal_i2c_sda_read(machine_i2c_obj_t *self) {
return mp_hal_pin_read(self->sda);
}
STATIC int mp_hal_i2c_start(machine_i2c_obj_t *self) {
mp_hal_i2c_sda_release(self);
mp_hal_i2c_delay(self);
int ret = mp_hal_i2c_scl_release(self);
mp_hal_i2c_sda_low(self);
mp_hal_i2c_delay(self);
return ret;
}
STATIC int mp_hal_i2c_stop(machine_i2c_obj_t *self) {
mp_hal_i2c_delay(self);
mp_hal_i2c_sda_low(self);
mp_hal_i2c_delay(self);
int ret = mp_hal_i2c_scl_release(self);
mp_hal_i2c_sda_release(self);
mp_hal_i2c_delay(self);
return ret;
}
STATIC void mp_hal_i2c_init(machine_i2c_obj_t *self, uint32_t freq) {
self->us_delay = 500000 / freq;
if (self->us_delay == 0) {
self->us_delay = 1;
}
mp_hal_pin_open_drain(self->scl);
mp_hal_pin_open_drain(self->sda);
mp_hal_i2c_stop(self); // ignore error
}
STATIC int mp_hal_i2c_write_byte(machine_i2c_obj_t *self, uint8_t val) {
mp_hal_i2c_delay(self);
mp_hal_i2c_scl_low(self);
for (int i = 7; i >= 0; i--) {
if ((val >> i) & 1) {
mp_hal_i2c_sda_release(self);
} else {
mp_hal_i2c_sda_low(self);
}
mp_hal_i2c_delay(self);
if (!mp_hal_i2c_scl_release(self)) {
mp_hal_i2c_sda_release(self);
return 0; // failure
}
mp_hal_i2c_scl_low(self);
}
mp_hal_i2c_sda_release(self);
mp_hal_i2c_delay(self);
if (!mp_hal_i2c_scl_release(self)) {
return 0; // failure
}
int ret = mp_hal_i2c_sda_read(self);
mp_hal_i2c_delay(self);
mp_hal_i2c_scl_low(self);
return !ret;
}
STATIC int mp_hal_i2c_read_byte(machine_i2c_obj_t *self, uint8_t *val, int nack) {
mp_hal_i2c_delay(self);
mp_hal_i2c_scl_low(self);
mp_hal_i2c_delay(self);
uint8_t data = 0;
for (int i = 7; i >= 0; i--) {
if (!mp_hal_i2c_scl_release(self)) {
return 0;
}
data = (data << 1) | mp_hal_i2c_sda_read(self);
mp_hal_i2c_scl_low(self);
mp_hal_i2c_delay(self);
}
*val = data;
// send ack/nack bit
if (!nack) {
mp_hal_i2c_sda_low(self);
}
mp_hal_i2c_delay(self);
if (!mp_hal_i2c_scl_release(self)) {
mp_hal_i2c_sda_release(self);
return 0; // failure
}
mp_hal_i2c_scl_low(self);
mp_hal_i2c_sda_release(self);
return 1; // success
}
// addr is the device address, memaddr is a memory address sent big-endian
STATIC int mp_hal_i2c_write_addresses(machine_i2c_obj_t *self, uint8_t addr,
uint32_t memaddr, uint8_t addrsize) {
if (!mp_hal_i2c_write_byte(self, addr << 1)) {
return 0; // error
}
for (int16_t i = addrsize - 8; i >= 0; i -= 8) {
if (!mp_hal_i2c_write_byte(self, memaddr >> i)) {
return 0; // error
}
}
return 1; // success
}
STATIC void mp_hal_i2c_write_mem(machine_i2c_obj_t *self, uint8_t addr,
uint32_t memaddr, uint8_t addrsize, const uint8_t *src, size_t len) {
// start the I2C transaction
if (!mp_hal_i2c_start(self)) {
goto er;
}
// write the slave address and the memory address within the slave
if (!mp_hal_i2c_write_addresses(self, addr, memaddr, addrsize)) {
goto er;
}
// write the buffer to the I2C memory
while (len--) {
if (!mp_hal_i2c_write_byte(self, *src++)) {
goto er;
}
}
// finish the I2C transaction
if (!mp_hal_i2c_stop(self)) {
goto er;
}
return;
er:
mp_hal_i2c_stop(self); // ignore error
nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "I2C bus error"));
}
STATIC void mp_hal_i2c_read_mem(machine_i2c_obj_t *self, uint8_t addr,
uint32_t memaddr, uint8_t addrsize, uint8_t *dest, size_t len) {
// start the I2C transaction
if (!mp_hal_i2c_start(self)) {
goto er;
}
if (addrsize) {
// write the slave address and the memory address within the slave
if (!mp_hal_i2c_write_addresses(self, addr, memaddr, addrsize)) {
goto er;
}
// i2c_read will do a repeated start, and then read the I2C memory
if (!mp_hal_i2c_start(self)) {
goto er;
}
}
if (!mp_hal_i2c_write_byte(self, (addr << 1) | 1)) {
goto er;
}
while (len--) {
if (!mp_hal_i2c_read_byte(self, dest++, len == 0)) {
goto er;
}
}
if (!mp_hal_i2c_stop(self)) {
goto er;
}
return;
er:
mp_hal_i2c_stop(self); // ignore error
nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "I2C bus error"));
}
STATIC void mp_hal_i2c_write(machine_i2c_obj_t *self, uint8_t addr, const uint8_t *src, size_t len) {
mp_hal_i2c_write_mem(self, addr, 0, 0, src, len);
}
STATIC void mp_hal_i2c_read(machine_i2c_obj_t *self, uint8_t addr, uint8_t *dest, size_t len) {
mp_hal_i2c_read_mem(self, addr, 0, 0, dest, len);
}
/******************************************************************************/
// MicroPython bindings for I2C
STATIC void machine_i2c_obj_init_helper(machine_i2c_obj_t *self, mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
enum { ARG_scl, ARG_sda, ARG_freq, ARG_timeout };
static const mp_arg_t allowed_args[] = {
{ MP_QSTR_scl, MP_ARG_REQUIRED | MP_ARG_OBJ },
{ MP_QSTR_sda, MP_ARG_REQUIRED | MP_ARG_OBJ },
{ MP_QSTR_freq, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 400000} },
{ MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 255} },
};
mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
self->scl = mp_hal_get_pin_obj(args[ARG_scl].u_obj);
self->sda = mp_hal_get_pin_obj(args[ARG_sda].u_obj);
self->us_timeout = args[ARG_timeout].u_int;
mp_hal_i2c_init(self, args[ARG_freq].u_int);
}
STATIC mp_obj_t machine_i2c_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
mp_arg_check_num(n_args, n_kw, 0, MP_OBJ_FUN_ARGS_MAX, true);
machine_i2c_obj_t *self = m_new_obj(machine_i2c_obj_t);
self->base.type = &machine_i2c_type;
mp_map_t kw_args;
mp_map_init_fixed_table(&kw_args, n_kw, args + n_args);
machine_i2c_obj_init_helper(self, n_args, args, &kw_args);
return (mp_obj_t)self;
}
STATIC mp_obj_t machine_i2c_obj_init(size_t n_args, const mp_obj_t *args, mp_map_t *kw_args) {
machine_i2c_obj_init_helper(args[0], n_args - 1, args + 1, kw_args);
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_KW(machine_i2c_init_obj, 1, machine_i2c_obj_init);
STATIC mp_obj_t machine_i2c_scan(mp_obj_t self_in) {
machine_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
mp_obj_t list = mp_obj_new_list(0, NULL);
// 7-bit addresses 0b0000xxx and 0b1111xxx are reserved
for (int addr = 0x08; addr < 0x78; ++addr) {
if (mp_hal_i2c_start(self)) {
int ack = mp_hal_i2c_write_byte(self, (addr << 1));
if (ack) {
mp_obj_list_append(list, MP_OBJ_NEW_SMALL_INT(addr));
}
mp_hal_i2c_stop(self); // ignore error
}
}
return list;
}
MP_DEFINE_CONST_FUN_OBJ_1(machine_i2c_scan_obj, machine_i2c_scan);
STATIC mp_obj_t machine_i2c_start(mp_obj_t self_in) {
machine_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
if (!mp_hal_i2c_start(self)) {
nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "I2C bus error"));
}
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_1(machine_i2c_start_obj, machine_i2c_start);
STATIC mp_obj_t machine_i2c_stop(mp_obj_t self_in) {
machine_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
if (!mp_hal_i2c_stop(self)) {
nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "I2C bus error"));
}
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_1(machine_i2c_stop_obj, machine_i2c_stop);
STATIC mp_obj_t machine_i2c_readinto(mp_obj_t self_in, mp_obj_t buf_in) {
machine_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
// get the buffer to read into
mp_buffer_info_t bufinfo;
mp_get_buffer_raise(buf_in, &bufinfo, MP_BUFFER_WRITE);
// do the read
uint8_t *dest = bufinfo.buf;
while (bufinfo.len--) {
if (!mp_hal_i2c_read_byte(self, dest++, bufinfo.len == 0)) {
nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "I2C bus error"));
}
}
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_2(machine_i2c_readinto_obj, machine_i2c_readinto);
STATIC mp_obj_t machine_i2c_write(mp_obj_t self_in, mp_obj_t buf_in) {
machine_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
// get the buffer to write from
mp_buffer_info_t bufinfo;
mp_get_buffer_raise(buf_in, &bufinfo, MP_BUFFER_READ);
// do the write
uint8_t *src = bufinfo.buf;
while (bufinfo.len--) {
if (!mp_hal_i2c_write_byte(self, *src++)) {
nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "I2C bus error"));
}
}
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_2(machine_i2c_write_obj, machine_i2c_write);
STATIC mp_obj_t machine_i2c_readfrom(mp_obj_t self_in, mp_obj_t addr_in, mp_obj_t nbytes_in) {
machine_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
vstr_t vstr;
vstr_init_len(&vstr, mp_obj_get_int(nbytes_in));
mp_hal_i2c_read(self, mp_obj_get_int(addr_in), (uint8_t*)vstr.buf, vstr.len);
return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
}
MP_DEFINE_CONST_FUN_OBJ_3(machine_i2c_readfrom_obj, machine_i2c_readfrom);
STATIC mp_obj_t machine_i2c_readfrom_into(mp_obj_t self_in, mp_obj_t addr_in, mp_obj_t buf_in) {
machine_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
mp_buffer_info_t bufinfo;
mp_get_buffer_raise(buf_in, &bufinfo, MP_BUFFER_WRITE);
mp_hal_i2c_read(self, mp_obj_get_int(addr_in), (uint8_t*)bufinfo.buf, bufinfo.len);
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_3(machine_i2c_readfrom_into_obj, machine_i2c_readfrom_into);
STATIC mp_obj_t machine_i2c_writeto(mp_obj_t self_in, mp_obj_t addr_in, mp_obj_t buf_in) {
machine_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
mp_buffer_info_t bufinfo;
mp_get_buffer_raise(buf_in, &bufinfo, MP_BUFFER_READ);
mp_hal_i2c_write(self, mp_obj_get_int(addr_in), bufinfo.buf, bufinfo.len);
return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_3(machine_i2c_writeto_obj, machine_i2c_writeto);
STATIC const mp_arg_t machine_i2c_mem_allowed_args[] = {
{ MP_QSTR_addr, MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_memaddr, MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_arg, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
{ MP_QSTR_addrsize, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 8} },
};
STATIC mp_obj_t machine_i2c_readfrom_mem(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
enum { ARG_addr, ARG_memaddr, ARG_n, ARG_addrsize };
machine_i2c_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);
mp_arg_val_t args[MP_ARRAY_SIZE(machine_i2c_mem_allowed_args)];
mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args,
MP_ARRAY_SIZE(machine_i2c_mem_allowed_args), machine_i2c_mem_allowed_args, args);
// create the buffer to store data into
vstr_t vstr;
vstr_init_len(&vstr, mp_obj_get_int(args[ARG_n].u_obj));
// do the transfer
mp_hal_i2c_read_mem(self, args[ARG_addr].u_int, args[ARG_memaddr].u_int,
args[ARG_addrsize].u_int, (uint8_t*)vstr.buf, vstr.len);
return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);
}
MP_DEFINE_CONST_FUN_OBJ_KW(machine_i2c_readfrom_mem_obj, 1, machine_i2c_readfrom_mem);
STATIC mp_obj_t machine_i2c_readfrom_mem_into(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
enum { ARG_addr, ARG_memaddr, ARG_buf, ARG_addrsize };
machine_i2c_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);
mp_arg_val_t args[MP_ARRAY_SIZE(machine_i2c_mem_allowed_args)];
mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args,
MP_ARRAY_SIZE(machine_i2c_mem_allowed_args), machine_i2c_mem_allowed_args, args);
// get the buffer to store data into
mp_buffer_info_t bufinfo;
mp_get_buffer_raise(args[ARG_buf].u_obj, &bufinfo, MP_BUFFER_WRITE);
// do the transfer
mp_hal_i2c_read_mem(self, args[ARG_addr].u_int, args[ARG_memaddr].u_int,
args[ARG_addrsize].u_int, bufinfo.buf, bufinfo.len);
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_KW(machine_i2c_readfrom_mem_into_obj, 1, machine_i2c_readfrom_mem_into);
STATIC mp_obj_t machine_i2c_writeto_mem(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
enum { ARG_addr, ARG_memaddr, ARG_buf, ARG_addrsize };
machine_i2c_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);
mp_arg_val_t args[MP_ARRAY_SIZE(machine_i2c_mem_allowed_args)];
mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args,
MP_ARRAY_SIZE(machine_i2c_mem_allowed_args), machine_i2c_mem_allowed_args, args);
// get the buffer to write the data from
mp_buffer_info_t bufinfo;
mp_get_buffer_raise(args[ARG_buf].u_obj, &bufinfo, MP_BUFFER_READ);
// do the transfer
mp_hal_i2c_write_mem(self, args[ARG_addr].u_int, args[ARG_memaddr].u_int,
args[ARG_addrsize].u_int, bufinfo.buf, bufinfo.len);
return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_KW(machine_i2c_writeto_mem_obj, 1, machine_i2c_writeto_mem);
STATIC const mp_rom_map_elem_t machine_i2c_locals_dict_table[] = {
{ MP_ROM_QSTR(MP_QSTR_init), MP_ROM_PTR(&machine_i2c_init_obj) },
{ MP_ROM_QSTR(MP_QSTR_scan), MP_ROM_PTR(&machine_i2c_scan_obj) },
// primitive I2C operations
{ MP_ROM_QSTR(MP_QSTR_start), MP_ROM_PTR(&machine_i2c_start_obj) },
{ MP_ROM_QSTR(MP_QSTR_stop), MP_ROM_PTR(&machine_i2c_stop_obj) },
{ MP_ROM_QSTR(MP_QSTR_readinto), MP_ROM_PTR(&machine_i2c_readinto_obj) },
{ MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&machine_i2c_write_obj) },
// standard bus operations
{ MP_ROM_QSTR(MP_QSTR_readfrom), MP_ROM_PTR(&machine_i2c_readfrom_obj) },
{ MP_ROM_QSTR(MP_QSTR_readfrom_into), MP_ROM_PTR(&machine_i2c_readfrom_into_obj) },
{ MP_ROM_QSTR(MP_QSTR_writeto), MP_ROM_PTR(&machine_i2c_writeto_obj) },
// memory operations
{ MP_ROM_QSTR(MP_QSTR_readfrom_mem), MP_ROM_PTR(&machine_i2c_readfrom_mem_obj) },
{ MP_ROM_QSTR(MP_QSTR_readfrom_mem_into), MP_ROM_PTR(&machine_i2c_readfrom_mem_into_obj) },
{ MP_ROM_QSTR(MP_QSTR_writeto_mem), MP_ROM_PTR(&machine_i2c_writeto_mem_obj) },
};
STATIC MP_DEFINE_CONST_DICT(machine_i2c_locals_dict, machine_i2c_locals_dict_table);
const mp_obj_type_t machine_i2c_type = {
{ &mp_type_type },
.name = MP_QSTR_I2C,
.make_new = machine_i2c_make_new,
.locals_dict = (mp_obj_dict_t*)&machine_i2c_locals_dict,
};
#endif // MICROPY_PY_MACHINE_I2C
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