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/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2020-2021 Damien P. George
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* Copyright (c) 2022 Robert Hammelrath
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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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#include "py/runtime.h"
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#include "py/mphal.h"
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#include "py/mperrno.h"
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#include "extmod/machine_i2c.h"
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#include "modmachine.h"
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#include "samd_soc.h"
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#include "pin_af.h"
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#include "clock_config.h"
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#define DEFAULT_I2C_FREQ (400000)
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#define RISETIME_NS (300)
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#define I2C_TIMEOUT (100)
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#define IS_BUS_BUSY (i2c->I2CM.STATUS.bit.BUSSTATE == 3)
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#define NACK_RECVD (i2c->I2CM.STATUS.bit.RXNACK == 1)
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#define IRQ_DATA_SENT (i2c->I2CM.INTFLAG.bit.MB == 1)
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#define IRQ_DATA_RECVD (i2c->I2CM.INTFLAG.bit.SB == 1)
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#define READ_MODE ((flags & MP_MACHINE_I2C_FLAG_READ) != 0)
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#define PREPARE_ACK i2c->I2CM.CTRLB.bit.ACKACT = 0
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#define PREPARE_NACK i2c->I2CM.CTRLB.bit.ACKACT = 1
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#define SET_STOP_STATE i2c_send_command(i2c, 0x03)
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enum state_t {
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state_done = 0,
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state_busy,
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state_buserr,
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state_nack
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};
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typedef struct _machine_i2c_obj_t {
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mp_obj_base_t base;
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Sercom *instance;
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uint8_t id;
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uint8_t scl;
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uint8_t sda;
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uint8_t state;
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uint32_t freq;
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uint32_t timeout;
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size_t len;
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uint8_t *buf;
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} machine_i2c_obj_t;
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extern Sercom *sercom_instance[];
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extern void *sercom_table[SERCOM_INST_NUM];
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STATIC void i2c_send_command(Sercom *i2c, uint8_t command) {
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i2c->I2CM.CTRLB.bit.CMD = command;
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while (i2c->I2CM.SYNCBUSY.bit.SYSOP) {
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}
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}
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void common_i2c_irq_handler(int i2c_id) {
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// handle Sercom I2C IRQ
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machine_i2c_obj_t *self = sercom_table[i2c_id];
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// Handle IRQ
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if (self != NULL) {
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Sercom *i2c = self->instance;
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// For now, clear all interrupts
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if (IRQ_DATA_RECVD) {
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if (self->len > 0) {
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*(self->buf)++ = i2c->I2CM.DATA.reg;
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self->len--;
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self->timeout = I2C_TIMEOUT;
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}
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if (self->len > 0) { // no ACK at the last byte
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PREPARE_ACK; // Send ACK
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i2c_send_command(i2c, 0x02);
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} else {
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PREPARE_NACK; // Send NACK after the last byte
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self->state = state_done;
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i2c->I2CM.INTFLAG.reg |= SERCOM_I2CM_INTFLAG_SB;
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}
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} else if (IRQ_DATA_SENT) {
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if (NACK_RECVD) { // e.g. NACK after adress for both read and write.
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self->state = state_nack; // force stop of transmission
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i2c->I2CM.INTFLAG.reg |= SERCOM_I2CM_INTFLAG_MB;
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} else if (self->len > 0) { // data to be sent
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i2c->I2CM.DATA.bit.DATA = *(self->buf)++;
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self->len--;
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self->timeout = I2C_TIMEOUT;
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} else { // No data left, if there was any.
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self->state = state_done;
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i2c->I2CM.INTFLAG.reg |= SERCOM_I2CM_INTFLAG_MB;
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}
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} else { // On any error, e.g. ARBLOST or BUSERROR, stop the transmission
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self->len = 0;
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self->state = state_buserr;
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i2c->I2CM.INTFLAG.reg |= SERCOM_I2CM_INTFLAG_ERROR;
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}
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}
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}
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STATIC void machine_i2c_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
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machine_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
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mp_printf(print, "I2C(%u, freq=%u, scl=%u, sda=%u)",
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self->id, self->freq, self->scl, self->sda);
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}
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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 *all_args) {
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enum { ARG_id, ARG_freq, ARG_scl, ARG_sda };
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static const mp_arg_t allowed_args[] = {
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{ MP_QSTR_id, MP_ARG_REQUIRED | MP_ARG_OBJ },
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{ MP_QSTR_freq, MP_ARG_INT, {.u_int = DEFAULT_I2C_FREQ} },
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{ MP_QSTR_scl, MP_ARG_REQUIRED | MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
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{ MP_QSTR_sda, MP_ARG_REQUIRED | MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
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};
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// Parse args.
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mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
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mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
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// Get I2C bus.
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int id = mp_obj_get_int(args[ARG_id].u_obj);
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if (id < 0 || id >= SERCOM_INST_NUM) {
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mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("I2C(%d) doesn't exist"), id);
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}
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// Get the peripheral object.
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machine_i2c_obj_t *self = mp_obj_malloc(machine_i2c_obj_t, &machine_hw_i2c_type);
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self->id = id;
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self->instance = sercom_instance[self->id];
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// Set SCL/SDA pins.
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sercom_pad_config_t scl_pad_config;
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self->scl = mp_hal_get_pin_obj(args[ARG_scl].u_obj);
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scl_pad_config = get_sercom_config(self->scl, self->id);
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sercom_pad_config_t sda_pad_config;
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self->sda = mp_hal_get_pin_obj(args[ARG_sda].u_obj);
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sda_pad_config = get_sercom_config(self->sda, self->id);
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if (sda_pad_config.pad_nr != 0 || scl_pad_config.pad_nr != 1) {
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mp_raise_ValueError(MP_ERROR_TEXT("invalid pin for sda or scl"));
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}
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sercom_table[self->id] = self;
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self->freq = args[ARG_freq].u_int;
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// Configure the Pin mux.
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mp_hal_set_pin_mux(self->scl, scl_pad_config.alt_fct);
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mp_hal_set_pin_mux(self->sda, sda_pad_config.alt_fct);
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// Set up the clocks
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enable_sercom_clock(self->id);
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// Initialise the I2C peripheral
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Sercom *i2c = self->instance;
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// Reset the device
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i2c->I2CM.CTRLA.reg = SERCOM_I2CM_CTRLA_SWRST;
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while (i2c->I2CM.SYNCBUSY.bit.SWRST == 1) {
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}
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// Set to master mode, inactivity timeout of 20 SCL cycles and speed.
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i2c->I2CM.CTRLA.reg = SERCOM_I2CM_CTRLA_MODE(0x05)
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| SERCOM_I2CM_CTRLA_INACTOUT(3)
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| SERCOM_I2CM_CTRLA_SPEED(self->freq > 400000 ? 1 : 0);
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// I2C is driven by the clock of GCLK Generator 2, with it's freq in variable bus_freq
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// baud = peripheral_freq / (2 * baudrate) - 5 - (rise_time * peripheral_freq) / 2
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// Just set the minimal configuration for standard and fast mode.
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// Set Baud. Assume ~300ns rise time. Maybe set later by a keyword argument.
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i2c->I2CM.BAUD.reg = get_apb_freq() / (2 * self->freq) - 5 - (get_apb_freq() / 1000000) * RISETIME_NS / 2000;
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// Enable interrupts
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sercom_register_irq(self->id, SERCOM_IRQ_TYPE_SPI);
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#if defined(MCU_SAMD21)
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NVIC_EnableIRQ(SERCOM0_IRQn + self->id);
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#elif defined(MCU_SAMD51)
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NVIC_EnableIRQ(SERCOM0_0_IRQn + 4 * self->id); // MB interrupt
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NVIC_EnableIRQ(SERCOM0_0_IRQn + 4 * self->id + 1); // SB interrupt
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NVIC_EnableIRQ(SERCOM0_0_IRQn + 4 * self->id + 3); // ERRROR interrupt
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#endif
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// Now enable I2C.
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sercom_enable(i2c, 1);
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// Force the bus state to idle
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i2c->I2CM.STATUS.bit.BUSSTATE = 1;
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return MP_OBJ_FROM_PTR(self);
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}
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STATIC int machine_i2c_transfer_single(mp_obj_base_t *self_in, uint16_t addr, size_t len, uint8_t *buf, unsigned int flags) {
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machine_i2c_obj_t *self = (machine_i2c_obj_t *)self_in;
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Sercom *i2c = self->instance;
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self->timeout = I2C_TIMEOUT;
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self->len = len;
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self->buf = buf;
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// Wait a while if the bus is busy
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while (IS_BUS_BUSY && self->timeout) {
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MICROPY_EVENT_POLL_HOOK
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if (--self->timeout == 0) {
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return -MP_ETIMEDOUT;
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}
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}
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// Enable interrupts and set the state
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i2c->I2CM.INTENSET.reg = SERCOM_I2CM_INTENSET_MB | SERCOM_I2CM_INTENSET_SB | SERCOM_I2CM_INTENSET_ERROR;
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self->state = state_busy;
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// Send the adress, which kicks off the transfer
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i2c->I2CM.ADDR.bit.ADDR = (addr << 1) | READ_MODE;
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// Transfer the data
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self->timeout = I2C_TIMEOUT;
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while (self->state == state_busy && self->timeout) {
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self->timeout--;
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MICROPY_EVENT_POLL_HOOK
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}
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i2c->I2CM.INTENCLR.reg = SERCOM_I2CM_INTENSET_MB | SERCOM_I2CM_INTENSET_SB | SERCOM_I2CM_INTENSET_ERROR;
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// Check the error states after the transfer is stopped
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if (self->state == state_nack) {
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SET_STOP_STATE;
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return self->len == len ? -MP_ENODEV : -MP_EIO;
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} else if (self->state == state_buserr) {
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SET_STOP_STATE;
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return -MP_EIO;
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} else if (self->timeout == 0) {
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SET_STOP_STATE;
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return -MP_ETIMEDOUT;
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}
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if (flags & MP_MACHINE_I2C_FLAG_STOP) {
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SET_STOP_STATE;
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}
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return len;
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}
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STATIC const mp_machine_i2c_p_t machine_i2c_p = {
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.transfer = mp_machine_i2c_transfer_adaptor,
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.transfer_single = machine_i2c_transfer_single,
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};
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MP_DEFINE_CONST_OBJ_TYPE(
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machine_hw_i2c_type,
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MP_QSTR_I2C,
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MP_TYPE_FLAG_NONE,
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make_new, machine_i2c_make_new,
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print, machine_i2c_print,
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protocol, &machine_i2c_p,
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locals_dict, &mp_machine_i2c_locals_dict
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);
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robert-hh
Damien George