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micropython/ports/samd/machine_i2c.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2020-2021 Damien P. George
* Copyright (c) 2022 Robert Hammelrath
*
* 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 "py/runtime.h"
#include "py/mphal.h"
#include "py/mperrno.h"
#include "extmod/machine_i2c.h"
#include "modmachine.h"
#include "samd_soc.h"
#include "pin_af.h"
#include "clock_config.h"
#define DEFAULT_I2C_FREQ (400000)
#define RISETIME_NS (200)
#define I2C_TIMEOUT (100)
#define IS_BUS_BUSY (i2c->I2CM.STATUS.bit.BUSSTATE == 3)
#define NACK_RECVD (i2c->I2CM.STATUS.bit.RXNACK == 1)
#define IRQ_DATA_SENT (i2c->I2CM.INTFLAG.bit.MB == 1)
#define IRQ_DATA_RECVD (i2c->I2CM.INTFLAG.bit.SB == 1)
#define READ_MODE ((flags & MP_MACHINE_I2C_FLAG_READ) != 0)
#define PREPARE_ACK i2c->I2CM.CTRLB.bit.ACKACT = 0
#define PREPARE_NACK i2c->I2CM.CTRLB.bit.ACKACT = 1
#define SET_STOP_STATE i2c_send_command(i2c, 0x03)
enum state_t {
state_done = 0,
state_busy,
state_buserr,
state_nack
};
typedef struct _machine_i2c_obj_t {
mp_obj_base_t base;
Sercom *instance;
uint8_t id;
uint8_t scl;
uint8_t sda;
uint8_t state;
uint32_t freq;
uint32_t timeout;
size_t len;
uint8_t *buf;
} machine_i2c_obj_t;
extern Sercom *sercom_instance[];
STATIC void i2c_send_command(Sercom *i2c, uint8_t command) {
i2c->I2CM.CTRLB.bit.CMD = command;
while (i2c->I2CM.SYNCBUSY.bit.SYSOP) {
}
}
void common_i2c_irq_handler(int i2c_id) {
// handle Sercom I2C IRQ
machine_i2c_obj_t *self = MP_STATE_PORT(sercom_table[i2c_id]);
// Handle IRQ
if (self != NULL) {
Sercom *i2c = self->instance;
// For now, clear all interrupts
if (IRQ_DATA_RECVD) {
if (self->len > 0) {
*(self->buf)++ = i2c->I2CM.DATA.reg;
self->len--;
self->timeout = I2C_TIMEOUT;
}
if (self->len > 0) { // no ACK at the last byte
PREPARE_ACK; // Send ACK
i2c_send_command(i2c, 0x02);
} else {
PREPARE_NACK; // Send NACK after the last byte
self->state = state_done;
i2c->I2CM.INTFLAG.reg |= SERCOM_I2CM_INTFLAG_SB;
}
} else if (IRQ_DATA_SENT) {
if (NACK_RECVD) { // e.g. NACK after adress for both read and write.
self->state = state_nack; // force stop of transmission
i2c->I2CM.INTFLAG.reg |= SERCOM_I2CM_INTFLAG_MB;
} else if (self->len > 0) { // data to be sent
i2c->I2CM.DATA.bit.DATA = *(self->buf)++;
self->len--;
self->timeout = I2C_TIMEOUT;
} else { // No data left, if there was any.
self->state = state_done;
i2c->I2CM.INTFLAG.reg |= SERCOM_I2CM_INTFLAG_MB;
}
} else { // On any error, e.g. ARBLOST or BUSERROR, stop the transmission
self->len = 0;
self->state = state_buserr;
i2c->I2CM.INTFLAG.reg |= SERCOM_I2CM_INTFLAG_ERROR;
}
}
}
STATIC void machine_i2c_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
machine_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
mp_printf(print, "I2C(%u, freq=%u, scl=%u, sda=%u)",
self->id, self->freq, self->scl, self->sda);
}
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) {
enum { ARG_id, ARG_freq, ARG_scl, ARG_sda };
static const mp_arg_t allowed_args[] = {
{ MP_QSTR_id, MP_ARG_REQUIRED | MP_ARG_OBJ },
{ MP_QSTR_freq, MP_ARG_INT, {.u_int = DEFAULT_I2C_FREQ} },
{ MP_QSTR_scl, MP_ARG_REQUIRED | MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
{ MP_QSTR_sda, MP_ARG_REQUIRED | MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
};
// Parse args.
mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
// Get I2C bus.
int id = mp_obj_get_int(args[ARG_id].u_obj);
if (id < 0 || id >= SERCOM_INST_NUM) {
mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("I2C(%d) doesn't exist"), id);
}
// Get the peripheral object.
machine_i2c_obj_t *self = mp_obj_malloc(machine_i2c_obj_t, &machine_i2c_type);
self->id = id;
self->instance = sercom_instance[self->id];
// Set SCL/SDA pins.
sercom_pad_config_t scl_pad_config;
self->scl = mp_hal_get_pin_obj(args[ARG_scl].u_obj);
scl_pad_config = get_sercom_config(self->scl, self->id);
sercom_pad_config_t sda_pad_config;
self->sda = mp_hal_get_pin_obj(args[ARG_sda].u_obj);
sda_pad_config = get_sercom_config(self->sda, self->id);
if (sda_pad_config.pad_nr != 0 || scl_pad_config.pad_nr != 1) {
mp_raise_ValueError(MP_ERROR_TEXT("invalid pin for sda or scl"));
}
MP_STATE_PORT(sercom_table[self->id]) = self;
self->freq = args[ARG_freq].u_int;
// Configure the Pin mux.
mp_hal_set_pin_mux(self->scl, scl_pad_config.alt_fct);
mp_hal_set_pin_mux(self->sda, sda_pad_config.alt_fct);
// Set up the clocks
enable_sercom_clock(self->id);
// Initialise the I2C peripheral
Sercom *i2c = self->instance;
// Reset the device
i2c->I2CM.CTRLA.reg = SERCOM_I2CM_CTRLA_SWRST;
while (i2c->I2CM.SYNCBUSY.bit.SWRST == 1) {
}
// Set to master mode, inactivity timeout of 20 SCL cycles and speed.
i2c->I2CM.CTRLA.reg = SERCOM_I2CM_CTRLA_MODE(0x05)
| SERCOM_I2CM_CTRLA_INACTOUT(3)
| SERCOM_I2CM_CTRLA_SPEED(self->freq > 400000 ? 1 : 0);
// I2C is driven by the clock of GCLK Generator 2, with it's freq in variable bus_freq
// baud = peripheral_freq / (2 * baudrate) - 5 - (rise_time * peripheral_freq) / 2
// Just set the minimal configuration for standard and fast mode.
// Set Baud. Assume ~300ns rise time. Maybe set later by a keyword argument.
int32_t baud = get_peripheral_freq() / (2 * self->freq) - 5 - (get_peripheral_freq() / 1000000) * RISETIME_NS / 2000;
if (baud < 0) {
baud = 0;
}
if (baud > 255) {
baud = 255;
}
i2c->I2CM.BAUD.reg = baud;
// Enable interrupts
sercom_register_irq(self->id, &common_i2c_irq_handler);
#if defined(MCU_SAMD21)
NVIC_EnableIRQ(SERCOM0_IRQn + self->id);
#elif defined(MCU_SAMD51)
NVIC_EnableIRQ(SERCOM0_0_IRQn + 4 * self->id); // MB interrupt
NVIC_EnableIRQ(SERCOM0_0_IRQn + 4 * self->id + 1); // SB interrupt
NVIC_EnableIRQ(SERCOM0_0_IRQn + 4 * self->id + 3); // ERRROR interrupt
#endif
// Now enable I2C.
sercom_enable(i2c, 1);
// Force the bus state to idle
i2c->I2CM.STATUS.bit.BUSSTATE = 1;
return MP_OBJ_FROM_PTR(self);
}
STATIC int machine_i2c_transfer_single(mp_obj_base_t *self_in, uint16_t addr, size_t len, uint8_t *buf, unsigned int flags) {
machine_i2c_obj_t *self = (machine_i2c_obj_t *)self_in;
Sercom *i2c = self->instance;
self->timeout = I2C_TIMEOUT;
self->len = len;
self->buf = buf;
// Wait a while if the bus is busy
while (IS_BUS_BUSY && self->timeout) {
MICROPY_EVENT_POLL_HOOK
if (--self->timeout == 0) {
return -MP_ETIMEDOUT;
}
}
// Enable interrupts and set the state
i2c->I2CM.INTENSET.reg = SERCOM_I2CM_INTENSET_MB | SERCOM_I2CM_INTENSET_SB | SERCOM_I2CM_INTENSET_ERROR;
self->state = state_busy;
// Send the adress, which kicks off the transfer
i2c->I2CM.ADDR.bit.ADDR = (addr << 1) | READ_MODE;
// Transfer the data
self->timeout = I2C_TIMEOUT;
while (self->state == state_busy && self->timeout) {
self->timeout--;
MICROPY_EVENT_POLL_HOOK
}
i2c->I2CM.INTENCLR.reg = SERCOM_I2CM_INTENSET_MB | SERCOM_I2CM_INTENSET_SB | SERCOM_I2CM_INTENSET_ERROR;
// Check the error states after the transfer is stopped
if (self->state == state_nack) {
SET_STOP_STATE;
return self->len == len ? -MP_ENODEV : -MP_EIO;
} else if (self->state == state_buserr) {
SET_STOP_STATE;
return -MP_EIO;
} else if (self->timeout == 0) {
SET_STOP_STATE;
return -MP_ETIMEDOUT;
}
if (flags & MP_MACHINE_I2C_FLAG_STOP) {
SET_STOP_STATE;
}
return len;
}
STATIC const mp_machine_i2c_p_t machine_i2c_p = {
.transfer = mp_machine_i2c_transfer_adaptor,
.transfer_single = machine_i2c_transfer_single,
};
MP_DEFINE_CONST_OBJ_TYPE(
machine_i2c_type,
MP_QSTR_I2C,
MP_TYPE_FLAG_NONE,
make_new, machine_i2c_make_new,
print, machine_i2c_print,
protocol, &machine_i2c_p,
locals_dict, &mp_machine_i2c_locals_dict
);
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