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machine_i2c: Add I2C bus clear support. #13281

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machine_i2c: Add I2C bus clear support. #13281

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a0db231
extmod/machine_i2c: Add support for I2C bus clear.
PepperoniPingu Dec 27, 2023
418653a
rp2/machine_i2c: Implement I2C bus clear on rp2.
PepperoniPingu Dec 27, 2023
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36 changes: 36 additions & 0 deletions extmod/machine_i2c.c
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Original file line number Diff line number Diff line change
Expand Up @@ -242,6 +242,26 @@ int mp_machine_soft_i2c_transfer(mp_obj_base_t *self_in, uint16_t addr, size_t n
return transfer_ret;
}

// return value:
// 0 - success
// <0 - error, with errno being the negative of the return value
int mp_machine_soft_i2c_clear_bus(mp_obj_base_t *self_in) {
machine_i2c_obj_t *self = (machine_i2c_obj_t *)self_in;

mp_hal_i2c_sda_release(self);
for (int i = 0; i < 10; i++) {
mp_hal_i2c_delay(self);
mp_hal_i2c_scl_low(self);
mp_hal_i2c_delay(self);
int ret = mp_hal_i2c_scl_release(self);
if (ret != 0) {
mp_hal_i2c_stop(self);
return ret;
}
}
return mp_hal_i2c_stop(self);
}

#endif // MICROPY_PY_MACHINE_SOFTI2C

/******************************************************************************/
Expand Down Expand Up @@ -365,6 +385,20 @@ STATIC mp_obj_t machine_i2c_stop(mp_obj_t self_in) {
}
MP_DEFINE_CONST_FUN_OBJ_1(machine_i2c_stop_obj, machine_i2c_stop);

STATIC mp_obj_t machine_i2c_clear_bus(mp_obj_t self_in) {
mp_obj_base_t *self = (mp_obj_base_t *)MP_OBJ_TO_PTR(self_in);
mp_machine_i2c_p_t *i2c_p = (mp_machine_i2c_p_t *)MP_OBJ_TYPE_GET_SLOT(self->type, protocol);
if (i2c_p->clear_bus == NULL) {
mp_raise_msg(&mp_type_OSError, MP_ERROR_TEXT("I2C operation not supported"));
}
int ret = i2c_p->clear_bus(self);
if (ret != 0) {
mp_raise_OSError(-ret);
}
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_1(machine_i2c_clear_bus_obj, machine_i2c_clear_bus);

STATIC mp_obj_t machine_i2c_readinto(size_t n_args, const mp_obj_t *args) {
mp_obj_base_t *self = (mp_obj_base_t *)MP_OBJ_TO_PTR(args[0]);
mp_machine_i2c_p_t *i2c_p = (mp_machine_i2c_p_t *)MP_OBJ_TYPE_GET_SLOT(self->type, protocol);
Expand Down Expand Up @@ -638,6 +672,7 @@ STATIC const mp_rom_map_elem_t machine_i2c_locals_dict_table[] = {
// 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_clear_bus), MP_ROM_PTR(&machine_i2c_clear_bus_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) },

Expand Down Expand Up @@ -726,6 +761,7 @@ STATIC const mp_machine_i2c_p_t mp_machine_soft_i2c_p = {
.init = mp_machine_soft_i2c_init,
.start = (int (*)(mp_obj_base_t *))mp_hal_i2c_start,
.stop = (int (*)(mp_obj_base_t *))mp_hal_i2c_stop,
.clear_bus = mp_machine_soft_i2c_clear_bus,
.read = mp_machine_soft_i2c_read,
.write = mp_machine_soft_i2c_write,
.transfer = mp_machine_soft_i2c_transfer,
Expand Down
2 changes: 2 additions & 0 deletions extmod/modmachine.h
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Original file line number Diff line number Diff line change
Expand Up @@ -158,6 +158,7 @@ typedef struct _mp_machine_i2c_p_t {
void (*init)(mp_obj_base_t *obj, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args);
int (*start)(mp_obj_base_t *obj);
int (*stop)(mp_obj_base_t *obj);
int (*clear_bus)(mp_obj_base_t *obj);
int (*read)(mp_obj_base_t *obj, uint8_t *dest, size_t len, bool nack);
int (*write)(mp_obj_base_t *obj, const uint8_t *src, size_t len);
int (*transfer)(mp_obj_base_t *obj, uint16_t addr, size_t n, mp_machine_i2c_buf_t *bufs, unsigned int flags);
Expand Down Expand Up @@ -252,6 +253,7 @@ MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(machine_bitstream_obj);
MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(machine_time_pulse_us_obj);

#if MICROPY_PY_MACHINE_I2C
int mp_machine_soft_i2c_clear_bus(mp_obj_base_t *self);
int mp_machine_i2c_transfer_adaptor(mp_obj_base_t *self, uint16_t addr, size_t n, mp_machine_i2c_buf_t *bufs, unsigned int flags);
int mp_machine_soft_i2c_transfer(mp_obj_base_t *self, uint16_t addr, size_t n, mp_machine_i2c_buf_t *bufs, unsigned int flags);
#endif
Expand Down
19 changes: 19 additions & 0 deletions ports/rp2/machine_i2c.c
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Original file line number Diff line number Diff line change
Expand Up @@ -189,7 +189,26 @@ STATIC int machine_i2c_transfer_single(mp_obj_base_t *self_in, uint16_t addr, si
}
}

STATIC int machine_i2c_clear_bus(mp_obj_base_t *self_in) {
machine_i2c_obj_t *self = (machine_i2c_obj_t *)self_in;
// Workaround issue with hardware I2C not supporting bus clear
mp_machine_soft_i2c_obj_t soft_i2c = {
.base = { &mp_machine_soft_i2c_type },
.us_delay = 500000 / self->freq + 1,
.us_timeout = self->timeout,
.scl = self->scl,
.sda = self->sda,
};
mp_hal_pin_open_drain(self->scl);
mp_hal_pin_open_drain(self->sda);
int ret = mp_machine_soft_i2c_clear_bus(&soft_i2c.base);
gpio_set_function(self->scl, GPIO_FUNC_I2C);
gpio_set_function(self->sda, GPIO_FUNC_I2C);
return ret;
}

STATIC const mp_machine_i2c_p_t machine_i2c_p = {
.clear_bus = machine_i2c_clear_bus,
.transfer = mp_machine_i2c_transfer_adaptor,
.transfer_single = machine_i2c_transfer_single,
};
Expand Down