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samd/DAC: Rework the DAC deinit() semantics.
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Since the two channels of a SAMD51 are not completely independent,
dac.deinit() now clears both channels, and both channels have to
be re-instantiated after a deinit().

Side change:
- rearrange some code lines.

Signed-off-by: robert-hh <robert@hammelrath.com>
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robert-hh committed Sep 22, 2024
1 parent 7546cc4 commit d5ae190
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Showing 3 changed files with 43 additions and 33 deletions.
7 changes: 4 additions & 3 deletions docs/samd/quickref.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -417,11 +417,12 @@ otherwise.

.. method:: deinit()

Deinitialize the DAC and release the resources used by it, especially the DMA channel
and the Timer. On most SAMD21 boards, there is just one timer available for
Deinitialize the DAC and release all resources used by it, especially the DMA channels
and the Timers. On most SAMD21 boards, there is just one timer available for
dac.write_timed() and adc.read_timed_into(). So they cannot run both at the same time,
and releasing the timer may be important. The DAC driver consumes a substantial amount
of current. deinit() will reduce that as well.
of current. deinit() will reduce that as well. After calling deinit(), the
DAC objects cannot be used any more and must be recreated.


Software SPI bus
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65 changes: 37 additions & 28 deletions ports/samd/machine_dac.c
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Original file line number Diff line number Diff line change
Expand Up @@ -46,16 +46,16 @@ typedef struct _dac_obj_t {
mp_obj_base_t base;
uint8_t id;
bool initialized;
mp_hal_pin_obj_t gpio_id;
uint8_t vref;
mp_hal_pin_obj_t gpio_id;
int8_t dma_channel;
int8_t tc_index;
bool busy;
uint32_t count;
mp_obj_t callback;
} dac_obj_t;
Dac *const dac_bases[] = DAC_INSTS;
static void dac_init(dac_obj_t *self, Dac *dac);
static void dac_init(dac_obj_t *self);
static mp_obj_t dac_deinit(mp_obj_t self_in);

#if defined(MCU_SAMD21)
Expand All @@ -65,7 +65,7 @@ static mp_obj_t dac_deinit(mp_obj_t self_in);
#define MAX_DAC_VREF (2)

static dac_obj_t dac_obj[] = {
{{&machine_dac_type}, 0, 0, PIN_PA02, DEFAULT_DAC_VREF, -1, -1, false, 1, NULL},
{{&machine_dac_type}, 0, 0, DEFAULT_DAC_VREF, PIN_PA02},
};

#elif defined(MCU_SAMD51)
Expand All @@ -75,8 +75,8 @@ static dac_obj_t dac_obj[] = {
#define MAX_DAC_VREF (3)

static dac_obj_t dac_obj[] = {
{{&machine_dac_type}, 0, 0, PIN_PA02, DEFAULT_DAC_VREF, -1, -1, false, 1, NULL},
{{&machine_dac_type}, 1, 0, PIN_PA05, DEFAULT_DAC_VREF, -1, -1, false, 1, NULL},
{{&machine_dac_type}, 0, 0, DEFAULT_DAC_VREF, PIN_PA02},
{{&machine_dac_type}, 1, 0, DEFAULT_DAC_VREF, PIN_PA05},
};
// According to Errata 2.9.2, VDDANA as ref value is not available. However it worked
// in tests. So I keep the selection here but set the default to Aref, which is usually
Expand Down Expand Up @@ -161,18 +161,20 @@ static mp_obj_t dac_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_
self->dma_channel = -1;
self->tc_index = -1;
self->initialized = false;
self->busy = false;

Dac *dac = dac_bases[0]; // Just one DAC
dac_init(self, dac);
dac_init(self);
// Set the port as given in self->gpio_id as DAC
mp_hal_set_pin_mux(self->gpio_id, ALT_FCT_DAC);

return MP_OBJ_FROM_PTR(self);
}

static void dac_init(dac_obj_t *self, Dac *dac) {
static void dac_init(dac_obj_t *self) {
// Init DAC
if (self->initialized == false) {
Dac *dac = dac_bases[0]; // Just one DAC

#if defined(MCU_SAMD21)

// Configuration SAMD21
Expand All @@ -194,9 +196,6 @@ static void dac_init(dac_obj_t *self, Dac *dac) {
#elif defined(MCU_SAMD51)

// Configuration SAMD51
// Enable APBD clocks and PCHCTRL clocks; GCLK5 at 48 MHz
MCLK->APBDMASK.reg |= MCLK_APBDMASK_DAC;
GCLK->PCHCTRL[DAC_GCLK_ID].reg = GCLK_PCHCTRL_GEN_GCLK5 | GCLK_PCHCTRL_CHEN;

// If the DAC is enabled it was already reset
// In that case just disable it.
Expand All @@ -206,6 +205,9 @@ static void dac_init(dac_obj_t *self, Dac *dac) {
while (dac->SYNCBUSY.bit.ENABLE) {
}
} else {
// Enable APBD clocks and PCHCTRL clocks; GCLK5 at 48 MHz
MCLK->APBDMASK.reg |= MCLK_APBDMASK_DAC;
GCLK->PCHCTRL[DAC_GCLK_ID].reg = GCLK_PCHCTRL_GEN_GCLK5 | GCLK_PCHCTRL_CHEN;
// Reset DAC registers
dac->CTRLA.bit.SWRST = 1;
while (dac->CTRLA.bit.SWRST) {
Expand All @@ -232,6 +234,10 @@ static void dac_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t
static mp_obj_t dac_write(mp_obj_t self_in, mp_obj_t value_in) {
Dac *dac = dac_bases[0]; // Just one DAC
dac_obj_t *self = self_in;

if (self->initialized == false) {
mp_raise_OSError(MP_ENODEV);
}
if (self->busy != false) {
mp_raise_OSError(MP_EBUSY);
}
Expand All @@ -241,8 +247,6 @@ static mp_obj_t dac_write(mp_obj_t self_in, mp_obj_t value_in) {
if (value < 0 || value > MAX_DAC_VALUE) {
mp_raise_ValueError(MP_ERROR_TEXT("value out of range"));
}
// Re-init, if required
dac_init(self, dac);
#if defined(MCU_SAMD21)
dac->DATA.reg = value;
#elif defined(MCU_SAMD51)
Expand All @@ -257,8 +261,10 @@ static mp_obj_t dac_write_timed(size_t n_args, const mp_obj_t *args) {
Dac *dac = dac_bases[0]; // Just one DAC used
dac_obj_t *self = args[0];
mp_buffer_info_t src;
// Re-init, if required
dac_init(self, dac);

if (self->initialized == false) {
mp_raise_OSError(MP_ENODEV);
}

mp_get_buffer_raise(args[1], &src, MP_BUFFER_READ);
if (n_args > 3) {
Expand Down Expand Up @@ -343,11 +349,8 @@ static mp_obj_t dac_write_timed(size_t n_args, const mp_obj_t *args) {
}
static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(dac_write_timed_obj, 3, 4, dac_write_timed);

static mp_obj_t dac_deinit(mp_obj_t self_in) {
dac_obj_t *self = self_in;
static void dac_deinit_channel(dac_obj_t *self) {
self->initialized = false;
// Reset the DAC to lower the current consumption as SAMD21
dac_bases[0]->CTRLA.bit.SWRST = 1;
if (self->dma_channel >= 0) {
dac_stop_dma(self->dma_channel, true);
free_dma_channel(self->dma_channel);
Expand All @@ -359,6 +362,20 @@ static mp_obj_t dac_deinit(mp_obj_t self_in) {
}
self->callback = MP_OBJ_NULL;
self->busy = false;
}

// Reset DAC and clear the DMA channel entries in the DAC objects.
void dac_deinit_all(void) {
// Reset the DAC to lower the current consumption as SAMD21
dac_bases[0]->CTRLA.bit.SWRST = 1;
dac_deinit_channel(&dac_obj[0]);
#if defined(MCU_SAMD51)
dac_deinit_channel(&dac_obj[1]);
#endif
}

static mp_obj_t dac_deinit(mp_obj_t self_in) {
dac_deinit_all();
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_1(dac_deinit_obj, dac_deinit);
Expand All @@ -370,18 +387,10 @@ static mp_obj_t machine_dac_busy(mp_obj_t self_in) {
}
static MP_DEFINE_CONST_FUN_OBJ_1(machine_dac_busy_obj, machine_dac_busy);

// Clear the DMA channel entry in the DAC object.
void dac_deinit_channel(void) {
dac_obj[0].dma_channel = -1;
#if defined(MCU_SAMD51)
dac_obj[1].dma_channel = -1;
#endif
}

static const mp_rom_map_elem_t dac_locals_dict_table[] = {
{ MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&dac_write_obj) },
{ MP_ROM_QSTR(MP_QSTR_busy), MP_ROM_PTR(&machine_dac_busy_obj) },
{ MP_ROM_QSTR(MP_QSTR_deinit), MP_ROM_PTR(&dac_deinit_obj) },
{ MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&dac_write_obj) },
{ MP_ROM_QSTR(MP_QSTR_write_timed), MP_ROM_PTR(&dac_write_timed_obj) },
};

Expand Down
4 changes: 2 additions & 2 deletions ports/samd/main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,7 @@

extern uint8_t _sstack, _estack, _sheap, _eheap;
extern void adc_deinit_all(void);
extern void dac_deinit_channel(void);
extern void dac_deinit_all(void);
extern void pin_irq_deinit_all(void);
extern void pwm_deinit_all(void);
extern void sercom_deinit_all(void);
Expand Down Expand Up @@ -96,7 +96,7 @@ void samd_main(void) {
adc_deinit_all();
#endif
#if MICROPY_PY_MACHINE_DAC
dac_deinit_channel();
dac_deinit_all();
#endif
pin_irq_deinit_all();
#if MICROPY_PY_MACHINE_PWM
Expand Down

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