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drivers/dht: made pullup configurable

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This commit is contained in:
Hauke Petersen 2016-01-21 16:22:26 +01:00
parent c5a0589332
commit f5f793c3f2
3 changed files with 56 additions and 57 deletions
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105
drivers/dht/dht.c
View File

@ -41,7 +41,6 @@
* internal API declaration
**********************************************************************/
static void dht_read_data(gpio_t dev, uint32_t *data, uint8_t *checksum);
static int dht_test_checksum(uint32_t data, uint8_t checksum);
void dht_parse_11(dht_data_t *data, float *outhum, float *outtemp);
void dht_parse_22(dht_data_t *data, float *outhum, float *outtemp);
@ -80,58 +79,6 @@ static int dht_test_checksum(uint32_t data, uint8_t checksum)
return ((checksum == sum) && (checksum != 0));
}
static void dht_read_data(gpio_t dev, uint32_t *data, uint8_t *checksum)
{
/* send init signal to device */
gpio_clear(dev);
xtimer_usleep(20 * MS_IN_USEC);
gpio_set(dev);
xtimer_usleep(40);
/* sync on device */
gpio_init(dev, GPIO_DIR_IN, GPIO_PULLUP);
while (!gpio_read(dev)) ;
while (gpio_read(dev)) ;
/*
* data is read in sequentially, highest bit first:
* 40 .. 24 23 .. 8 7 .. 0
* [humidity][temperature][checksum]
*/
/* read all the bits */
uint64_t les_bits = 0x00000000000000;
for (int c = 0; c < 40; c++) {
les_bits <<= 1; /* this is a nop in the first iteration, but
we must not shift the last bit */
/* wait for start of bit */
while (!gpio_read(dev)) ;
unsigned long start = xtimer_now();
/* wait for end of bit */
while (gpio_read(dev)) ;
/* calculate bit length (long 1, short 0) */
unsigned long stop = xtimer_now();
/* compensate for overflow if needed */
if (stop < start) {
stop = UINT32_MAX - stop;
start = 0;
}
if ((stop - start) > 40) {
/* read 1, set bit */
les_bits |= 0x0000000000000001;
}
else {
/* read 0, don't set bit */
}
}
*checksum = les_bits & 0x00000000000000FF;
*data = (les_bits >> 8) & 0x00000000FFFFFFFF;
gpio_init(dev, GPIO_DIR_OUT, GPIO_PULLUP);
gpio_set(dev);
}
/***********************************************************************
* public API implementation
**********************************************************************/
@ -153,7 +100,7 @@ int dht_init(dht_t *dev, const dht_params_t *params)
memcpy(dev, params, sizeof(dht_t));
if (gpio_init(dev->pin, GPIO_DIR_OUT, GPIO_PULLUP) == -1) {
if (gpio_init(dev->pin, GPIO_DIR_OUT, dev->pull) == -1) {
return -1;
}
gpio_set(dev->pin);
@ -169,8 +116,54 @@ int dht_read_raw(dht_t *dev, dht_data_t *outdata)
uint32_t data;
uint8_t checksum;
/* read raw data */
dht_read_data(dev->pin, &data, &checksum);
/* send init signal to device */
gpio_clear(dev->pin);
xtimer_usleep(20 * MS_IN_USEC);
gpio_set(dev->pin);
xtimer_usleep(40);
/* sync on device */
gpio_init(dev->pin, GPIO_DIR_IN, dev->pull);
while (!gpio_read(dev->pin)) ;
while (gpio_read(dev->pin)) ;
/*
* data is read in sequentially, highest bit first:
* 40 .. 24 23 .. 8 7 .. 0
* [humidity][temperature][checksum]
*/
/* read all the bits */
uint64_t les_bits = 0x00000000000000;
for (int c = 0; c < 40; c++) {
les_bits <<= 1; /* this is a nop in the first iteration, but
we must not shift the last bit */
/* wait for start of bit */
while (!gpio_read(dev->pin)) ;
unsigned long start = xtimer_now();
/* wait for end of bit */
while (gpio_read(dev->pin)) ;
/* calculate bit length (long 1, short 0) */
unsigned long stop = xtimer_now();
/* compensate for overflow if needed */
if (stop < start) {
stop = UINT32_MAX - stop;
start = 0;
}
if ((stop - start) > 40) {
/* read 1, set bit */
les_bits |= 0x0000000000000001;
}
else {
/* read 0, don't set bit */
}
}
checksum = les_bits & 0x00000000000000FF;
data = (les_bits >> 8) & 0x00000000FFFFFFFF;
gpio_init(dev->pin, GPIO_DIR_OUT, dev->pull);
gpio_set(dev->pin);
/* check checksum */
int ret = dht_test_checksum(data, checksum);

6
drivers/dht/include/dht_params.h
View File

@ -35,9 +35,13 @@ extern "C" {
#ifndef DHT_PARAM_TYPE
#define DHT_PARAM_TYPE (DHT11)
#endif
#ifndef DHT_PARAM_PULL
#define DHT_PARAM_PULL (GPIO_PULLUP)
#endif
#define DHT_PARAMS_DEFAULT {.pin = DHT_PARAM_PIN, \
.type = DHT_PARAM_TYPE}
.type = DHT_PARAM_TYPE, \
.pull = DHT_PARAM_PULL}
/**@}*/
/**

2
drivers/include/dht.h
View File

@ -59,6 +59,8 @@ typedef enum {
typedef struct {
gpio_t pin; /**< GPIO pin of the device's data pin */
dht_type_t type; /**< type of the DHT device */
gpio_pp_t pull; /**< internal pull resistor configuration, set to
* GPIO_NOPULL when using an external pull-up */
} dht_t;
/**