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micropython/extmod/machine_i2c.c
Radomir Dopieralski 219245e10f extmod/machine_i2c: Add support for the addrsize parameter in mem xfers. 
The memory read/write I2C functions now take an optional keyword-only
parameter that specifies the number of bits in the memory address.
Only mem-addrs that are a multiple of 8-bits are supported (otherwise
the behaviour is undefined).

Due to the integer type used for the address, for values larger than 32
bits, only 32 bits of address will be sent, and the rest will be padded
with 0s. Right now no exception is raised when that happens. For values
smaller than 8, no address is sent. Also no exception then.

Tested with a VL6180 sensor, which has 16-bit register addresses.

Due to code refactoring, this patch reduces stmhal and esp8266 builds
by about 50 bytes.
2016-09-28 14:45:29 +10:00

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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
// Clock stretching limit, so that we don't get stuck.
#define I2C_STRETCH_LIMIT 255
typedef struct _machine_i2c_obj_t {
mp_obj_base_t base;
uint32_t us_delay;
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 void mp_hal_i2c_scl_release(machine_i2c_obj_t *self) {
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 (int count = I2C_STRETCH_LIMIT; mp_hal_pin_read(self->scl) == 0 && count; --count) {
mp_hal_delay_us_fast(1);
}
}
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 void mp_hal_i2c_start(machine_i2c_obj_t *self) {
mp_hal_i2c_sda_release(self);
mp_hal_i2c_delay(self);
mp_hal_i2c_scl_release(self);
mp_hal_i2c_sda_low(self);
mp_hal_i2c_delay(self);
}
STATIC void 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);
mp_hal_i2c_scl_release(self);
mp_hal_i2c_sda_release(self);
mp_hal_i2c_delay(self);
}
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);
}
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);
mp_hal_i2c_scl_release(self);
mp_hal_i2c_scl_low(self);
}
mp_hal_i2c_sda_release(self);
mp_hal_i2c_delay(self);
mp_hal_i2c_scl_release(self);
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--) {
mp_hal_i2c_scl_release(self);
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);
mp_hal_i2c_scl_release(self);
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
mp_hal_i2c_start(self);
// 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
mp_hal_i2c_stop(self);
return;
er:
mp_hal_i2c_stop(self);
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
mp_hal_i2c_start(self);
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
mp_hal_i2c_start(self);
}
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;
}
}
mp_hal_i2c_stop(self);
return;
er:
mp_hal_i2c_stop(self);
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 };
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_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);
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) {
mp_hal_i2c_start(self);
int ack = mp_hal_i2c_write_byte(self, (addr << 1) | 1);
if (ack) {
mp_obj_list_append(list, MP_OBJ_NEW_SMALL_INT(addr));
}
mp_hal_i2c_stop(self);
}
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);
mp_hal_i2c_start(self);
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);
mp_hal_i2c_stop(self);
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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