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drivers/sx127x: fix reset for sx1272 devices.

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- The previous implementation wrongly assumes that sx1272 and 1276
  use the same logic level for triggering a reset.
- The timeout values were to short to guarantee proper reset when
  coming from POR.
This commit is contained in:
Michel Rottleuthner 2019-06-12 09:49:17 +02:00
parent f337f42738
commit 6e4214843a
1 changed files with 42 additions and 7 deletions
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49
drivers/sx127x/sx127x.c
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@ -40,6 +40,22 @@
#define ENABLE_DEBUG (0)
#include "debug.h"
/* The reset signal must be applied for at least 100 µs to trigger the manual
reset of the device. To ensure this value is big enough even with an
inaccurate clock source, an additional 10 % error margin is added. */
#define SX127X_MANUAL_RESET_SIGNAL_LEN_US (110U)
/* After triggering a manual reset the device needs at least 5 ms to become
ready before interacting with it. To ensure this value is big enough even
with an inaccurate clock source, an additional 10 % error margin is added. */
#define SX127X_MANUAL_RESET_WAIT_FOR_READY_US (5500U)
/* When the device is started by enabling its power supply for the first time
i.e. on Power-on-Reset (POR), it needs at least 10 ms after the POR cycle is
done to become ready. To ensure this value is big enough even with an
inaccurate clock source, an additional 10 % error margin is added. */
#define SX127X_POR_WAIT_FOR_READY_US (11U * US_PER_MS)
/* Internal functions */
static int _init_spi(sx127x_t *dev);
static int _init_gpios(sx127x_t *dev);
@ -71,7 +87,13 @@ int sx127x_reset(const sx127x_t *dev)
* See http://www.semtech.com/images/datasheet/sx1276.pdf for SX1276
* See http://www.semtech.com/images/datasheet/sx1272.pdf for SX1272
*
* For SX1272:
* 1. Set Reset pin to HIGH for at least 100 us
*
* For SX1276:
* 1. Set NReset pin to LOW for at least 100 us
*
* For both:
* 2. Set NReset in Hi-Z state
* 3. Wait at least 5 milliseconds
*/
@ -95,17 +117,15 @@ int sx127x_reset(const sx127x_t *dev)
gpio_set(dev->params.rx_switch_pin);
#endif
/* Set reset pin to 0 */
gpio_clear(dev->params.reset_pin);
/* set reset pin to the state that triggers manual reset */
gpio_write(dev->params.reset_pin, SX127X_POR_ACTIVE_LOGIC_LEVEL);
/* Wait 1 ms */
xtimer_usleep(1000);
xtimer_usleep(SX127X_MANUAL_RESET_SIGNAL_LEN_US);
/* Put reset pin in High-Z */
gpio_init(dev->params.reset_pin, GPIO_IN);
/* Wait 10 ms */
xtimer_usleep(1000 * 10);
xtimer_usleep(SX127X_MANUAL_RESET_WAIT_FOR_READY_US);
return 0;
}
@ -124,8 +144,23 @@ int sx127x_init(sx127x_t *dev)
return -SX127X_ERR_NODEV;
}
/* Check if the reset pin is defined */
if (dev->params.reset_pin == GPIO_UNDEF) {
DEBUG("[sx127x] error: No reset pin defined.\n");
return -SX127X_ERR_GPIOS;
}
_init_timers(dev);
xtimer_usleep(1000); /* wait 1 millisecond */
/* reset pin should be left floating during POR */
gpio_init(dev->params.reset_pin, GPIO_IN);
/* wait till device signals end of POR cycle */
while ((gpio_read(dev->params.reset_pin) > 0) ==
SX127X_POR_ACTIVE_LOGIC_LEVEL ) {};
/* wait for the device to become ready */
xtimer_usleep(SX127X_POR_WAIT_FOR_READY_US);
sx127x_reset(dev);