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rp2/machine_pin: Add support for setting pin drive strength & slew rate #17906

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rp2/machine_pin: Add support for setting pin drive strength & slew rate #17906

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27 changes: 19 additions & 8 deletions docs/library/machine.Pin.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,7 @@ Usage Model::
Constructors
------------

.. class:: Pin(id, mode=-1, pull=-1, *, value=None, drive=0, alt=-1)
.. class:: Pin(id, mode=-1, pull=-1, *, value=None, drive=-1, alt=-1, slew=-1)

Access the pin peripheral (GPIO pin) associated with the given ``id``. If
additional arguments are given in the constructor then they are used to initialise
Expand Down Expand Up @@ -87,16 +87,21 @@ Constructors
output pin value if given, otherwise the state of the pin peripheral remains
unchanged.

- ``drive`` specifies the output power of the pin and can be one of: ``Pin.DRIVE_0``,
``Pin.DRIVE_1``, etc., increasing in drive strength. The actual current driving
capabilities are port dependent. Not all ports implement this argument.
- ``drive`` specifies the drive strength of the pin (applicable only for output pins)
and can be one of: ``Pin.DRIVE_0``, ``Pin.DRIVE_1``, etc., increasing in drive strength.
The actual current driving capabilities are port dependent. Not all ports implement this
argument.

- ``alt`` specifies an alternate function for the pin and the values it can take are
port dependent. This argument is valid only for ``Pin.ALT`` and ``Pin.ALT_OPEN_DRAIN``
modes. It may be used when a pin supports more than one alternate function. If only
one pin alternate function is supported the this argument is not required. Not all
ports implement this argument.

- ``slew`` specifies the slew rate of the pin (applicable only for output pins) and can
be one of: ``Pin.SLEW_SLOW``, ``Pin.SLEW_FAST``, etc. The actual slew rate capabilities
are port dependent. Not all ports implement this argument.

As specified above, the Pin class allows to set an alternate function for a particular
pin, but it does not specify any further operations on such a pin. Pins configured in
alternate-function mode are usually not used as GPIO but are instead driven by other
Expand All @@ -108,7 +113,7 @@ Constructors
Methods
-------

.. method:: Pin.init(mode=-1, pull=-1, *, value=None, drive=0, alt=-1)
.. method:: Pin.init(mode=-1, pull=-1, *, value=None, drive=-1, alt=-1, slew=-1)

Re-initialise the pin using the given parameters. Only those arguments that
are specified will be set. The rest of the pin peripheral state will remain
Expand Down Expand Up @@ -270,9 +275,15 @@ not all constants are available on all ports.
Pin.DRIVE_1
Pin.DRIVE_2

Selects the pin drive strength. A port may define additional drive
constants with increasing number corresponding to increasing drive
strength.
Selects the output pin drive strength. A port may define additional or
entirely custom drive constants with increasing number corresponding to
increasing drive strength.

.. data:: Pin.SLEW_SLOW
Pin.SLEW_FAST

Selects the output pin slew rate. A port may define additional or entirely
custom drive constants with constant corresponding to specific slew rate.

.. data:: Pin.IRQ_FALLING
Pin.IRQ_RISING
Expand Down
3 changes: 3 additions & 0 deletions docs/rp2/quickref.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -162,6 +162,9 @@ Use the :ref:`machine.Pin <machine.Pin>` class::
p4 = Pin(4, Pin.IN, Pin.PULL_UP) # enable internal pull-up resistor
p5 = Pin(5, Pin.OUT, value=1) # set pin high on creation

# create output pin on GPIO6 with 8mA drive strength and slow slew rate
p6 = Pin(6, Pin.OUT, drive=Pin.DRIVE_8, slew=Pin.SLEW_SLOW)

Programmable IO (PIO)
---------------------

Expand Down
55 changes: 53 additions & 2 deletions ports/rp2/machine_pin.c
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Original file line number Diff line number Diff line change
Expand Up @@ -195,11 +195,26 @@ static void machine_pin_print(const mp_print_t *print, mp_obj_t self_in, mp_prin
machine_pin_obj_t *self = self_in;
uint funcsel = gpio_get_function(self->id);
qstr mode_qst;
bool is_output;
mp_uint_t drive;
mp_uint_t slew;
static const qstr drive2str[] = {
[GPIO_DRIVE_STRENGTH_2MA] = MP_QSTR_DRIVE_2,
[GPIO_DRIVE_STRENGTH_4MA] = MP_QSTR_DRIVE_4,
[GPIO_DRIVE_STRENGTH_8MA] = MP_QSTR_DRIVE_8,
[GPIO_DRIVE_STRENGTH_12MA] = MP_QSTR_DRIVE_12
};
static const qstr slew2str[] = {
[GPIO_SLEW_RATE_SLOW] = MP_QSTR_SLEW_SLOW,
[GPIO_SLEW_RATE_FAST] = MP_QSTR_SLEW_FAST,
};

if (!is_ext_pin(self)) {
is_output = gpio_is_dir_out(self->id);
if (funcsel == GPIO_FUNC_SIO) {
if (GPIO_IS_OPEN_DRAIN(self->id)) {
mode_qst = MP_QSTR_OPEN_DRAIN;
} else if (gpio_is_dir_out(self->id)) {
} else if (is_output) {
mode_qst = MP_QSTR_OUT;
} else {
mode_qst = MP_QSTR_IN;
Expand All @@ -220,6 +235,12 @@ static void machine_pin_print(const mp_print_t *print, mp_obj_t self_in, mp_prin
mp_printf(print, ", pull=%q", MP_QSTR_PULL_DOWN);
}
}

if (is_output) {
drive = (mp_uint_t)gpio_get_drive_strength(self->id);
mp_printf(print, ", drive=%q", drive2str[drive]);
}

if (funcsel != GPIO_FUNC_SIO) {
const machine_pin_af_obj_t *af = machine_pin_find_alt_by_index(self, funcsel);
if (af == NULL) {
Expand All @@ -228,6 +249,11 @@ static void machine_pin_print(const mp_print_t *print, mp_obj_t self_in, mp_prin
mp_printf(print, ", alt=%q", af->name);
}
}

if (is_output) {
slew = gpio_get_slew_rate(self->id);
mp_printf(print, ", slew=%q", slew2str[slew]);
}
} else {
#if MICROPY_HW_PIN_EXT_COUNT
mode_qst = (self->is_output) ? MP_QSTR_OUT : MP_QSTR_IN;
Expand All @@ -238,13 +264,20 @@ static void machine_pin_print(const mp_print_t *print, mp_obj_t self_in, mp_prin
}

enum {
ARG_mode, ARG_pull, ARG_value, ARG_alt
ARG_mode,
ARG_pull,
ARG_value,
ARG_drive,
ARG_alt,
ARG_slew,
};
static const mp_arg_t allowed_args[] = {
{MP_QSTR_mode, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE}},
{MP_QSTR_pull, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE}},
{MP_QSTR_value, MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE}},
{MP_QSTR_drive, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1}},
{MP_QSTR_alt, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = GPIO_FUNC_SIO}},
{MP_QSTR_slew, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1}},
};

static mp_obj_t machine_pin_obj_init_helper(const machine_pin_obj_t *self, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
Expand Down Expand Up @@ -284,6 +317,18 @@ static mp_obj_t machine_pin_obj_init_helper(const machine_pin_obj_t *self, size_
gpio_put(self->id, value);
}
mp_hal_pin_output(self->id);

// Configure drive strength
mp_uint_t drive = args[ARG_drive].u_int;
if (drive != -1) {
gpio_set_drive_strength(self->id, drive);
}

// Configure slew rate
mp_uint_t slew = args[ARG_slew].u_int;
if (slew != -1) {
gpio_set_slew_rate(self->id, slew);
}
} else if (mode == MACHINE_PIN_MODE_OPEN_DRAIN) {
mp_hal_pin_open_drain_with_value(self->id, value == -1 ? 1 : value);
} else {
Expand Down Expand Up @@ -504,6 +549,12 @@ static const mp_rom_map_elem_t machine_pin_locals_dict_table[] = {
{ MP_ROM_QSTR(MP_QSTR_ALT), MP_ROM_INT(MACHINE_PIN_MODE_ALT) },
{ MP_ROM_QSTR(MP_QSTR_PULL_UP), MP_ROM_INT(GPIO_PULL_UP) },
{ MP_ROM_QSTR(MP_QSTR_PULL_DOWN), MP_ROM_INT(GPIO_PULL_DOWN) },
{ MP_ROM_QSTR(MP_QSTR_DRIVE_2), MP_ROM_INT(GPIO_DRIVE_STRENGTH_2MA) },
{ MP_ROM_QSTR(MP_QSTR_DRIVE_4), MP_ROM_INT(GPIO_DRIVE_STRENGTH_4MA) },
{ MP_ROM_QSTR(MP_QSTR_DRIVE_8), MP_ROM_INT(GPIO_DRIVE_STRENGTH_8MA) },
{ MP_ROM_QSTR(MP_QSTR_DRIVE_12), MP_ROM_INT(GPIO_DRIVE_STRENGTH_12MA) },
{ MP_ROM_QSTR(MP_QSTR_SLEW_SLOW), MP_ROM_INT(GPIO_SLEW_RATE_SLOW) },
{ MP_ROM_QSTR(MP_QSTR_SLEW_FAST), MP_ROM_INT(GPIO_SLEW_RATE_FAST) },
{ MP_ROM_QSTR(MP_QSTR_IRQ_RISING), MP_ROM_INT(GPIO_IRQ_EDGE_RISE) },
{ MP_ROM_QSTR(MP_QSTR_IRQ_FALLING), MP_ROM_INT(GPIO_IRQ_EDGE_FALL) },

Expand Down
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