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PWM: added workaround for Edison's problem with 0% duty

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As described in issue #91, on Edison setting 0% duty doesn't
disable the PWM on a pin completely.

Therefore we add a couple of Edison-specific _pre functions
and an internal PWM state variable, which we use to toggle PWM
enabled/disabled based on what duty is set for the pin.

Closes #91.

Signed-off-by: Alex Tereschenko <alext.mkrs@gmail.com>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>
This commit is contained in:
Alex Tereschenko
2016-05-24 23:12:24 +02:00
committed by Brendan Le Foll
parent c413a43d5a
commit 8af6843566
3 changed files with 48 additions and 0 deletions
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32
src/x86/intel_edison_fab_c.c
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@@ -76,6 +76,9 @@ static int mmap_fd = 0;
static int mmap_size;
static unsigned int mmap_count = 0;
// PWM 0% duty workaround state array
static int pwm_disabled[4] = { 0 };
mraa_result_t
mraa_intel_edison_spi_lsbmode_replace(mraa_spi_context dev, mraa_boolean_t lsb)
{
@@ -367,6 +370,30 @@ mraa_intel_edison_aio_init_post(mraa_aio_context dev)
return mraa_gpio_write(tristate, 1);
}
mraa_result_t
mraa_intel_edison_pwm_enable_pre(mraa_pwm_context dev, int enable) {
// PWM 0% duty workaround: update state array
// if someone first ran write(0) and then enable(1).
if ((pwm_disabled[dev->pin] == 1) && (enable == 1)) { pwm_disabled[dev->pin] = 0; }
return MRAA_SUCCESS;
}
mraa_result_t
mraa_intel_edison_pwm_write_pre(mraa_pwm_context dev, float percentage) {
// PWM 0% duty workaround: set the state array and enable/disable pin accordingly
if (percentage == 0.0f) {
syslog(LOG_INFO, "edison_pwm_write_pre (pwm%i): requested zero duty cycle, disabling PWM on the pin", dev->pin);
pwm_disabled[dev->pin] = 1;
return mraa_pwm_enable(dev, 0);
} else if (pwm_disabled[dev->pin] == 1) {
syslog(LOG_INFO, "edison_pwm_write_pre (pwm%i): Re-enabling the pin after setting non-zero duty", dev->pin);
pwm_disabled[dev->pin] = 0;
return mraa_pwm_enable(dev, 1);
}
return MRAA_SUCCESS;
}
mraa_result_t
mraa_intel_edison_pwm_init_pre(int pin)
{
@@ -414,6 +441,7 @@ mraa_intel_edison_pwm_init_pre(int pin)
mraa_result_t
mraa_intel_edison_pwm_init_post(mraa_pwm_context pwm)
{
pwm_disabled[pwm->pin] = 0;
return mraa_gpio_write(tristate, 1);
}
@@ -802,6 +830,8 @@ mraa_intel_edison_miniboard(mraa_board_t* b)
}
b->adv_func->gpio_init_post = &mraa_intel_edison_gpio_init_post;
b->adv_func->pwm_init_pre = &mraa_intel_edison_pwm_init_pre;
b->adv_func->pwm_enable_pre = &mraa_intel_edison_pwm_enable_pre;
b->adv_func->pwm_write_pre = &mraa_intel_edison_pwm_write_pre;
b->adv_func->i2c_init_pre = &mraa_intel_edison_i2c_init_pre;
b->adv_func->i2c_set_frequency_replace = &mraa_intel_edison_i2c_freq;
b->adv_func->spi_init_pre = &mraa_intel_edison_spi_init_pre;
@@ -1259,6 +1289,8 @@ mraa_intel_edison_fab_c()
b->adv_func->aio_init_post = &mraa_intel_edison_aio_init_post;
b->adv_func->pwm_init_pre = &mraa_intel_edison_pwm_init_pre;
b->adv_func->pwm_init_post = &mraa_intel_edison_pwm_init_post;
b->adv_func->pwm_enable_pre = &mraa_intel_edison_pwm_enable_pre;
b->adv_func->pwm_write_pre = &mraa_intel_edison_pwm_write_pre;
b->adv_func->spi_init_pre = &mraa_intel_edison_spi_init_pre;
b->adv_func->spi_init_post = &mraa_intel_edison_spi_init_post;
b->adv_func->gpio_mode_replace = &mraa_intel_edison_gpio_mode_replace;