Hi Greg,
We have experimentally found out that this change helps with somewhat quirky
CO2/VOC-sensor.
Best Regards,
Juha Niskanen
From f09acf45e1c94e454e3379a165aebe601e39b22d Mon Sep 17 00:00:00 2001
From: Juha Niskanen <juha.niska...@haltian.com>
Date: Thu, 5 Mar 2020 09:55:57 +0200
Subject: [PATCH] drivers/sensors/sgp30.c: reset I2C in case init msg takes too
long
---
drivers/sensors/sgp30.c | 95 ++++++++++++++++++++++++++++++++++++++++---
include/nuttx/sensors/sgp30.h | 5 +++
2 files changed, 94 insertions(+), 6 deletions(-)
diff --git a/drivers/sensors/sgp30.c b/drivers/sensors/sgp30.c
index ad0f515..5a8ce07 100644
--- a/drivers/sensors/sgp30.c
+++ b/drivers/sensors/sgp30.c
@@ -72,6 +72,8 @@
#endif
#define SGP30_I2C_RETRIES 3
+#define SGP30_INIT_RETRIES 5
+#define SGP30_INIT_LIMIT_MS 10
/****************************************************************************
* Private
@@ -375,6 +377,29 @@ static uint8_t sgp30_crc_word(uint16_t word)
}
/****************************************************************************
+ * Name: sgp30_soft_reset
+ ****************************************************************************/
+
+static int sgp30_soft_reset(FAR struct sgp30_dev_s *priv)
+{
+ struct i2c_msg_s msg[1];
+ uint8_t buf[1];
+ int ret = 0;
+
+ buf[0] = CONFIG_SGP30_RESET_SECOND_BYTE;
+
+ msg[0].frequency = CONFIG_SGP30_I2C_FREQUENCY;
+ msg[0].addr = CONFIG_SGP30_RESET_ADDR;
+ msg[0].flags = 0;
+ msg[0].buffer = buf;
+ msg[0].length = 1;
+
+ ret = sgp30_do_transfer(priv->i2c, msg, 1);
+
+ return (ret >= 0) ? OK : ret;
+}
+
+/****************************************************************************
* Name: sgp30_set_command_param
****************************************************************************/
@@ -424,16 +449,39 @@ static int sgp30_check_data_crc(FAR const struct sgp30_word_s *words,
*
****************************************************************************/
-static bool has_time_passed(struct timespec curr,
- struct timespec start,
+static bool has_time_passed(FAR struct timespec *curr,
+ FAR struct timespec *start,
unsigned int secs_since_start)
{
- if ((long)((start.tv_sec + secs_since_start) - curr.tv_sec) == 0)
+ if ((long)((start->tv_sec + secs_since_start) - curr->tv_sec) == 0)
+ {
+ return start->tv_nsec <= curr->tv_nsec;
+ }
+
+ return (long)((start->tv_sec + secs_since_start) - curr->tv_sec) <= 0;
+}
+
+/****************************************************************************
+ * Name: time_has_passed_ms
+ *
+ * Description:
+ * Return true if curr >= start + msecs_since_start
+ *
+ ****************************************************************************/
+
+static bool time_has_passed_ms(FAR struct timespec *curr,
+ FAR struct timespec *start,
+ unsigned int msecs_since_start)
+{
+ uint32_t start_msec = start->tv_nsec / (1000 * 1000);
+ uint32_t curr_msec = curr->tv_nsec / (1000 * 1000);
+
+ if (start->tv_sec < curr->tv_sec)
{
- return start.tv_nsec <= curr.tv_nsec;
+ curr_msec += 1000 * ((long)(curr->tv_sec - start->tv_sec));
}
- return (long)((start.tv_sec + secs_since_start) - curr.tv_sec) <= 0;
+ return (start_msec + msecs_since_start) <= curr_msec;
}
/****************************************************************************
@@ -536,6 +584,7 @@ static int sgp30_open(FAR struct file *filep)
sgp30_read_cmd(priv, SGP30_CMD_GET_FEATURE_SET_VERSION, buf, 1) >= 0
&& sgp30_check_data_crc(buf, 1) >= 0)
{
+ struct timespec start, curr;
sgp30_dbg("serial id: %04x-%04x-%04x\n",
sgp30_data_word_to_uint16(serial + 0),
sgp30_data_word_to_uint16(serial + 1),
@@ -546,12 +595,46 @@ static int sgp30_open(FAR struct file *filep)
add_sensor_randomness((buf[0].crc << 24) ^ (serial[0].crc << 16) ^
(serial[1].crc << 8) ^ (serial[2].crc << 0));
+ clock_gettime(CLOCK_REALTIME, &start);
ret = sgp30_write_cmd(priv, SGP30_CMD_INIT_AIR_QUALITY, NULL, 0);
if (ret < 0)
{
sgp30_dbg("sgp30_write_cmd(SGP30_CMD_INIT_AIR_QUALITY) failed, %d\n",
ret);
}
+ else
+ {
+ uint32_t repeat = SGP30_INIT_RETRIES;
+ clock_gettime(CLOCK_REALTIME, &curr);
+ sgp30_dbg("sgp30_write_cmd(SGP30_CMD_INIT_AIR_QUALITY)\n");
+ while (repeat-- && time_has_passed_ms(&curr, &start, SGP30_INIT_LIMIT_MS))
+ {
+ /* Infrequently the SGP30_CMD_INIT_AIR_QUALITY message delivery
+ * takes suspiciously long time (SGP30_INIT_LIMIT_MS or more) and
+ * in these cases the TVOC values will never reach the correct
+ * level (not even after 24 hours).
+ * If this delay is detected, the sensor is given a "General Call"
+ * soft reset as described in the SGP30 datasheet and initialization
+ * is tried again after CONFIG_SGP30_RESET_DELAY_US.
+ */
+
+ ret = sgp30_soft_reset(priv);
+ if (ret < 0)
+ {
+ sgp30_dbg("sgp30_soft_reset failed, %d\n", ret);
+ return ret;
+ }
+ nxsig_usleep(CONFIG_SGP30_RESET_DELAY_US);
+
+ clock_gettime(CLOCK_REALTIME, &start);
+ ret = sgp30_write_cmd(priv, SGP30_CMD_INIT_AIR_QUALITY, NULL, 0);
+ clock_gettime(CLOCK_REALTIME, &curr);
+ if (ret < 0)
+ {
+ sgp30_dbg("sgp30_write_cmd(SGP30_CMD_INIT_AIR_QUALITY) failed, %d\n", ret);
+ }
+ }
+ }
}
else
{
@@ -646,7 +729,7 @@ static ssize_t sgp30_read(FAR struct file *filep, FAR char *buffer,
clock_gettime(CLOCK_REALTIME, &ts);
- while (!has_time_passed(ts, priv->last_update, 1))
+ while (!has_time_passed(&ts, &priv->last_update, 1))
{
if (filep->f_oflags & O_NONBLOCK)
{
diff --git a/include/nuttx/sensors/sgp30.h b/include/nuttx/sensors/sgp30.h
index 36e7907..538a7bb 100644
--- a/include/nuttx/sensors/sgp30.h
+++ b/include/nuttx/sensors/sgp30.h
@@ -47,6 +47,11 @@
#define CONFIG_SGP30_ADDR 0x58
+#define CONFIG_SGP30_RESET_ADDR 0x00
+#define CONFIG_SGP30_RESET_SECOND_BYTE 0x06
+
+#define CONFIG_SGP30_RESET_DELAY_US 300000
+
/****************************************************************************
* Public Types
****************************************************************************/
--
2.7.4
