drivers: sensor: ccs811: rework data fetch to prepare for non-polled use
The original implementation relied on the DATA_READY bit of the STATUS register to indicate when a reading was available. This bit remains clear for the first several readings produced by the CCS811. When INT_DATARDY is set in MEAS_MODE the nINT signal will remain asserted until ALG_RESULT_DATA is read. If this is treated as a LEVEL signal, which is the common case in Zephyr, gating the read of ALG_RESULT_DATA on DATA_READY means the signal will never be cleared, and the interrupt callback will be repeated immediately. Since the STATUS register value is part of the ALG_RESULT_DATA block just read the whole thing, and provide its content to the user only if the DATA_READY bit is set. Signed-off-by: Peter A. Bigot <pab@pabigot.com>
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1 changed files with 19 additions and 29 deletions
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@ -73,11 +73,10 @@ static inline u8_t error_from_status(int status)
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static int ccs811_sample_fetch(struct device *dev, enum sensor_channel chan)
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{
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struct ccs811_data *drv_data = dev->driver_data;
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int rc;
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int tries;
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u16_t buf[4];
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u8_t cmd;
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int status;
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int rv = -EIO;
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/* Check data ready flag for the measurement interval */
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#ifdef CONFIG_CCS811_DRIVE_MODE_1
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@ -88,50 +87,41 @@ static int ccs811_sample_fetch(struct device *dev, enum sensor_channel chan)
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tries = 601;
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#endif
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while (tries-- > 0) {
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do {
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const u8_t cmd = CCS811_REG_ALG_RESULT_DATA;
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set_wake(drv_data, true);
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status = fetch_status(drv_data->i2c);
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if (status < 0) {
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goto out;
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rc = i2c_write_read(drv_data->i2c, DT_INST_0_AMS_CCS811_BASE_ADDRESS,
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&cmd, sizeof(cmd),
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(u8_t *)buf, sizeof(buf));
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set_wake(drv_data, false);
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if (rc < 0) {
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return -EIO;
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}
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status = buf[2];
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if (status & CCS811_STATUS_ERROR) {
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LOG_ERR("CCS811 ERROR ID %02x",
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error_from_status(status));
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goto out;
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return -EIO;
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}
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if ((status & CCS811_STATUS_DATA_READY) || tries == 0) {
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if (status & CCS811_STATUS_DATA_READY) {
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break;
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}
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set_wake(drv_data, false);
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k_sleep(K_MSEC(100));
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}
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} while (--tries > 0);
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if (!(status & CCS811_STATUS_DATA_READY)) {
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LOG_ERR("Sensor data not available");
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goto out;
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return -EIO;
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}
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cmd = CCS811_REG_ALG_RESULT_DATA;
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if (i2c_write_read(drv_data->i2c, DT_INST_0_AMS_CCS811_BASE_ADDRESS,
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&cmd, sizeof(cmd),
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(u8_t *)buf, 8) < 0) {
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LOG_ERR("Failed to read conversion data.");
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goto out;
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}
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drv_data->co2 = sys_be16_to_cpu(buf[0]);
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drv_data->voc = sys_be16_to_cpu(buf[1]);
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drv_data->status = buf[2] & 0xff;
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drv_data->error = buf[2] >> 8;
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drv_data->status = status;
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drv_data->error = error_from_status(status);
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drv_data->resistance = sys_be16_to_cpu(buf[3]);
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rv = 0;
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out:
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set_wake(drv_data, false);
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return rv;
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return 0;
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}
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static int ccs811_channel_get(struct device *dev,
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