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sensor: tmp116: Add support for tmp117, fix calculation issues

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- Added support for TMP117 in existing driver for TMP116
  The Texas Instruments TMP117 is a higher precision upgrade
   from TMP116. It shares most functionality, but has a
   differing device ID.
   This patch will run with the hardware IDs of both devices.

- Fixed an int promote issue in tmp116_channel_get
  Negative temperature values in drv_data->sample were not
  processed correctly.
  The error occured during integer promotion from u16_t to s32_t
  in this code line:
     tmp = (s32_t)drv_data->sample * TMP116_RESOLUTION;

  By first promoting to s16_t, the correct result is obtained:
     tmp = (s16_t)drv_data->sample * (s32_t)TMP116_RESOLUTION;

- Made temperature resolution compatible to sensor API
  The fractional part of the temperature was returned as a
  multiple of 10^-7 deg.Celsius.
  This differs from the resolution sugegsted by the sensor API,
  which is 10^-6.

  The driver is now returning temperature readings with
  a resolution of 10^-6 deg. Celsius.

- The changed driver was tested using following hardware:
  TMP117 attached to disco_l475_iot1 via i2c1

Signed-off-by: Hans Wilmers <hans@wilmers.no>
This commit is contained in:
Hans Wilmers 2019-11-25 13:37:48 +01:00 • committed by Anas Nashif
commit 5b1a524348
2 changed files with 5 additions and 4 deletions
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8
drivers/sensor/tmp116/tmp116.c
View file

@ -51,7 +51,7 @@ static inline int tmp116_device_id_check(struct device *dev)
return -EIO;
}
if (value != TMP116_DEVICE_ID) {
if ((value != TMP116_DEVICE_ID) && (value != TMP117_DEVICE_ID)) {
LOG_ERR("%s: Failed to match the device IDs!",
DT_INST_0_TI_TMP116_LABEL);
return -EINVAL;
@ -100,9 +100,9 @@ static int tmp116_channel_get(struct device *dev, enum sensor_channel chan,
* See datasheet "Temperature Results and Limits" section for more
* details on processing sample data.
*/
tmp = (s32_t)drv_data->sample * TMP116_RESOLUTION;
val->val1 = tmp / 10000000; /* Tens of uCelsius */
val->val2 = tmp % 10000000;
tmp = ((s16_t)drv_data->sample * (s32_t)TMP116_RESOLUTION) / 10;
val->val1 = tmp / 1000000; /* uCelsius */
val->val2 = tmp % 1000000;
return 0;
}

1
drivers/sensor/tmp116/tmp116.h
View file

@ -22,6 +22,7 @@
#define TMP116_RESOLUTION_DIV 10000000
#define TMP116_DEVICE_ID 0x1116
#define TMP117_DEVICE_ID 0x0117
struct tmp116_data {
struct device *i2c;