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zephyr/machine_i2c_target: Implement I2CTarget class.
Tested and working on rpi_pico and nucleo_wb55rg. Signed-off-by: Damien George <[email protected]>
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‎ports/zephyr/boards/nucleo_wb55rg.conf

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@@ -4,6 +4,7 @@ CONFIG_NETWORKING=n
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CONFIG_FLASH=y
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CONFIG_FLASH_MAP=y
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CONFIG_I2C=y
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CONFIG_I2C_TARGET=y
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CONFIG_SPI=y
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# Bluetooth

‎ports/zephyr/boards/rpi_pico.conf

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@@ -13,6 +13,7 @@ CONFIG_NETWORKING=n
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CONFIG_FLASH=y
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CONFIG_FLASH_MAP=y
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CONFIG_I2C=y
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CONFIG_I2C_TARGET=y
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CONFIG_SPI=y
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# MicroPython config.

‎ports/zephyr/machine_i2c_target.c

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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) 2025 Damien P. George
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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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// This file is never compiled standalone, it's included directly from
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// extmod/machine_i2c_target.c via MICROPY_PY_MACHINE_I2C_TARGET_INCLUDEFILE.
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#include <zephyr/drivers/i2c.h>
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#include "zephyr_device.h"
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typedef struct _machine_i2c_target_obj_t {
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mp_obj_base_t base;
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const struct device *dev;
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struct i2c_target_config cfg;
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uint8_t state;
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uint8_t data_byte;
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} machine_i2c_target_obj_t;
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static machine_i2c_target_obj_t machine_i2c_target_obj[] = {
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{.base = {&machine_i2c_target_type}, .dev = NULL},
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};
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/******************************************************************************/
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// zephyr bindings
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//
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// Note that it's possible to get callbacks in either of these sequences:
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// - read_requested read_processed read_processed ... (eg STM32)
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// - read_requested read_processed read_requested read_processed ... (eg RP2xxx / Design Ware)
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static int i2c_target_write_requested(struct i2c_target_config *config) {
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machine_i2c_target_obj_t *self = CONTAINER_OF(config, machine_i2c_target_obj_t, cfg);
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self->state = STATE_WRITING;
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machine_i2c_target_data_addr_match(&machine_i2c_target_data[0], false);
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return 0;
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}
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static int i2c_target_write_received(struct i2c_target_config *config, uint8_t val) {
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machine_i2c_target_obj_t *self = CONTAINER_OF(config, machine_i2c_target_obj_t, cfg);
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machine_i2c_target_data_t *data = &machine_i2c_target_data[0];
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self->data_byte = val;
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machine_i2c_target_data_write_request(self, data);
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return 0;
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}
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static int i2c_target_read_requested(struct i2c_target_config *config, uint8_t *val) {
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machine_i2c_target_obj_t *self = CONTAINER_OF(config, machine_i2c_target_obj_t, cfg);
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machine_i2c_target_data_t *data = &machine_i2c_target_data[0];
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if (self->state != STATE_READING) {
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machine_i2c_target_data_addr_match(data, true);
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machine_i2c_target_data_read_request(self, data);
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self->state = STATE_READING;
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}
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*val = self->data_byte;
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return 0;
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}
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static int i2c_target_read_processed(struct i2c_target_config *config, uint8_t *val) {
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machine_i2c_target_obj_t *self = CONTAINER_OF(config, machine_i2c_target_obj_t, cfg);
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machine_i2c_target_data_t *data = &machine_i2c_target_data[0];
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machine_i2c_target_data_read_request(self, data);
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*val = self->data_byte;
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return 0;
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}
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// called only on stop, not restart
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static int i2c_target_stop(struct i2c_target_config *config) {
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machine_i2c_target_obj_t *self = CONTAINER_OF(config, machine_i2c_target_obj_t, cfg);
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if (self->state == STATE_IDLE) {
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// Assume a stop without a start is a 0-byte write.
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machine_i2c_target_data_addr_match(&machine_i2c_target_data[0], false);
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}
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self->state = STATE_IDLE;
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machine_i2c_target_data_t *data = &machine_i2c_target_data[0];
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machine_i2c_target_data_stop(data);
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return 0;
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}
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static struct i2c_target_callbacks i2c_target_callbacks = {
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.write_requested = i2c_target_write_requested,
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.read_requested = i2c_target_read_requested,
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.write_received = i2c_target_write_received,
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.read_processed = i2c_target_read_processed,
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.stop = i2c_target_stop,
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};
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/******************************************************************************/
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// I2CTarget port implementation
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static inline size_t mp_machine_i2c_target_get_index(machine_i2c_target_obj_t *self) {
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return 0;
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}
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static void mp_machine_i2c_target_event_callback(machine_i2c_target_irq_obj_t *irq) {
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char dummy;
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void *orig_top = MP_STATE_THREAD(stack_top);
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mp_uint_t orig_limit = MP_STATE_THREAD(stack_limit);
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MP_STATE_THREAD(stack_top) = &dummy;
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MP_STATE_THREAD(stack_limit) = CONFIG_ISR_STACK_SIZE - 512;
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mp_irq_handler(&irq->base);
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MP_STATE_THREAD(stack_top) = orig_top;
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MP_STATE_THREAD(stack_limit) = orig_limit;
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}
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static size_t mp_machine_i2c_target_read_bytes(machine_i2c_target_obj_t *self, size_t len, uint8_t *buf) {
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buf[0] = self->data_byte;
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return 1;
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}
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static size_t mp_machine_i2c_target_write_bytes(machine_i2c_target_obj_t *self, size_t len, const uint8_t *buf) {
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self->data_byte = buf[0];
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return 1;
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}
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static inline void mp_machine_i2c_target_irq_config(machine_i2c_target_obj_t *self, unsigned int trigger) {
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(void)self;
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(void)trigger;
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}
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static mp_obj_t mp_machine_i2c_target_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_addr, ARG_addrsize, ARG_mem, ARG_mem_addrsize, 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_addr, MP_ARG_REQUIRED | MP_ARG_INT },
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{ MP_QSTR_addrsize, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 7} },
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{ MP_QSTR_mem, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
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{ MP_QSTR_mem_addrsize, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 8} },
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};
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// Parse arguments.
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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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const struct device *dev = zephyr_device_find(args[ARG_id].u_obj);
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machine_i2c_target_obj_t *self = &machine_i2c_target_obj[0];
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if (!(self->dev == NULL || self->dev == dev)) {
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mp_raise_ValueError(MP_ERROR_TEXT("only one I2CTarget supported"));
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}
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self->dev = dev;
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self->cfg.flags = 0;
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self->cfg.address = args[ARG_addr].u_int;
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self->cfg.callbacks = &i2c_target_callbacks;
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// Initialise data.
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self->state = STATE_IDLE;
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MP_STATE_PORT(machine_i2c_target_mem_obj)[0] = args[ARG_mem].u_obj;
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machine_i2c_target_data_t *data = &machine_i2c_target_data[0];
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machine_i2c_target_data_init(data, args[ARG_mem].u_obj, args[ARG_mem_addrsize].u_int);
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// Initialise the I2C target.
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int ret = i2c_target_register(self->dev, &self->cfg);
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if (ret < 0) {
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mp_raise_OSError(-ret);
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}
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return MP_OBJ_FROM_PTR(self);
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}
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static void mp_machine_i2c_target_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
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machine_i2c_target_obj_t *self = MP_OBJ_TO_PTR(self_in);
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mp_printf(print, "I2CTarget(%s, addr=%u)",
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self->dev == NULL ? "" : self->dev->name, self->cfg.address);
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}
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static void mp_machine_i2c_target_deinit(machine_i2c_target_obj_t *self) {
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i2c_target_unregister(self->dev, &self->cfg);
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self->dev = NULL;
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}

‎ports/zephyr/main.c

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#include "shared/runtime/pyexec.h"
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#include "shared/readline/readline.h"
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#include "extmod/modbluetooth.h"
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#include "extmod/modmachine.h"
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#if MICROPY_VFS
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#include "extmod/vfs.h"
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#if MICROPY_PY_MACHINE
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machine_pin_deinit();
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#endif
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#if MICROPY_PY_MACHINE_I2C_TARGET
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mp_machine_i2c_target_deinit_all();
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#endif
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#if MICROPY_PY_THREAD
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mp_thread_deinit();

‎ports/zephyr/mpconfigport.h

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#define MICROPY_PY_MACHINE (1)
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#define MICROPY_PY_MACHINE_INCLUDEFILE "ports/zephyr/modmachine.c"
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#define MICROPY_PY_MACHINE_I2C (1)
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#ifdef CONFIG_I2C_TARGET
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#define MICROPY_PY_MACHINE_I2C_TARGET (1)
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#define MICROPY_PY_MACHINE_I2C_TARGET_INCLUDEFILE "ports/zephyr/machine_i2c_target.c"
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#define MICROPY_PY_MACHINE_I2C_TARGET_MAX (1)
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#define MICROPY_PY_MACHINE_I2C_TARGET_HARD_IRQ (1)
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#endif
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#define MICROPY_PY_MACHINE_SOFTI2C (1)
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#define MICROPY_PY_MACHINE_SPI (1)
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#define MICROPY_PY_MACHINE_SPI_MSB (SPI_TRANSFER_MSB)

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