Difference between revisions of "Iis2dh"

Revision as of 05:08, 18 October 2021

Notes on STMicro IIS22DH high frequency MEMS accelerometer.

• https://community.st.com/s/question/0D50X00009XkdfV/understanding-acceleration-data-from-iis2dh (Excerpt from this post copied to section below . . .)

A promising project on Github:

• https://github.com/STMicroelectronics/iis2dh
• https://github.com/STMicroelectronics/STMems_Standard_C_drivers/tree/master/iis2dh_STdC/examples
• https://github.com/STMicroelectronics/STMems_Standard_C_drivers/blob/master/iis2dh_STdC/examples/iis2dh_read_data_polling.c

Symbols in the polling code example from STMicroelectronic/iis2dh repo are defined in a sub-part of sdk-nrf modules/hal/ project space:

guest@ubuntu-vm:~/embedded/z3-on-var/modules/hal/st$ grep -nr IIS2DH_2g ./*
./sensor/stmemsc/iis2dh_STdC/driver/iis2dh_reg.h:742:  IIS2DH_2g   = 0,
./sensor/stmemsc/iis2dh_STdC/driver/iis2dh_reg.c:636:    case IIS2DH_2g:
./sensor/stmemsc/iis2dh_STdC/driver/iis2dh_reg.c:637:      *val = IIS2DH_2g;
./sensor/stmemsc/iis2dh_STdC/driver/iis2dh_reg.c:649:      *val = IIS2DH_2g;

guest@ubuntu-vm:~/embedded/z3-on-var/modules/hal/st$ grep -nr IIS2DH_ODR_1Hz ./*
./sensor/stmemsc/iis2dh_STdC/driver/iis2dh_reg.h:707:  IIS2DH_ODR_1Hz                         = 0x01,
./sensor/stmemsc/iis2dh_STdC/driver/iis2dh_reg.c:402:    case IIS2DH_ODR_1Hz:
./sensor/stmemsc/iis2dh_STdC/driver/iis2dh_reg.c:403:      *val = IIS2DH_ODR_1Hz;

guest@ubuntu-vm:~/embedded/z3-on-var/modules/hal/st$ grep -nr IIS2DH_TEMP_ENABLE ./*
./sensor/stmemsc/iis2dh_STdC/driver/iis2dh_reg.h:692:  IIS2DH_TEMP_ENABLE   = 3,
./sensor/stmemsc/iis2dh_STdC/driver/iis2dh_reg.c:285:    case IIS2DH_TEMP_ENABLE:
./sensor/stmemsc/iis2dh_STdC/driver/iis2dh_reg.c:286:      *val = IIS2DH_TEMP_ENABLE;
guest@ubuntu-vm:~/embedded/z3-on-var/modules/hal/st$ grep -nr PROPERTY_ENABLE ./*

And really the above project is pulled in to Nordic's sdk-nrf. Looks to be at a slightly older, or at least different version, but driver header and sources at https://github.com/STMicroelectronics/iis2dh are the same as in the STMicro hal code in Nordic sdk-nrf v1.6.1.

^ IIS2DH Control Registers As C Structures

An excerpt from Nordic sdk-nrf modules/hal/st/sensor/stmemsc/iis2dh_STdC/driver/iis2dh_reg.h:

#define IIS2DH_CTRL_REG4             0x23U
typedef struct {
#if DRV_BYTE_ORDER == DRV_LITTLE_ENDIAN
  uint8_t sim               : 1;
  uint8_t st                : 2;
  uint8_t hr                : 1;
  uint8_t fs                : 2;
  uint8_t ble               : 1;
  uint8_t bdu               : 1;
#elif DRV_BYTE_ORDER == DRV_BIG_ENDIAN
  uint8_t bdu               : 1;
  uint8_t ble               : 1;
  uint8_t fs                : 2;
  uint8_t hr                : 1;
  uint8_t st                : 2;
  uint8_t sim               : 1;
#endif /* DRV_BYTE_ORDER */
} iis2dh_ctrl_reg4_t;

^ Possible Zephyr Driver Routines for IIS2DH

Following routines are not obvious nor mentioned anywhere in Zephyr Project documentation found so far, nor are they hinted at by any trace of analogous routines in the build artifacts of Zephyr lis2dh sample app. But may we use these following routines in app level code we want to have talking with STMicro's IIS2DH sensor? . . .

 1 guest@vm:~/projects/zephyr-based/project-stage-1$ grep -nr stmdev_ctx_t ./*
 2 Binary file ./build/zephyr/zephyr.elf matches
 3 Binary file ./build/zephyr/zephyr_prebuilt.elf matches
 4 ./build/zephyr/zephyr.lst:55935:int32_t iis2dh_read_reg(stmdev_ctx_t* ctx, uint8_t reg, uint8_t* data,
 5 ./build/zephyr/zephyr.lst:55953:int32_t iis2dh_write_reg(stmdev_ctx_t* ctx, uint8_t reg, uint8_t* data,
 6 ./build/zephyr/zephyr.lst:55973:int32_t iis2dh_operating_mode_set(stmdev_ctx_t *ctx, iis2dh_op_md_t val)
 7 ./build/zephyr/zephyr.lst:56065:int32_t iis2dh_data_rate_set(stmdev_ctx_t *ctx, iis2dh_odr_t val)
 8 ./build/zephyr/zephyr.lst:56107:int32_t iis2dh_full_scale_set(stmdev_ctx_t *ctx, iis2dh_fs_t val)
 9 ./build/zephyr/zephyr.lst:56149:int32_t iis2dh_block_data_update_set(stmdev_ctx_t *ctx, uint8_t val)
10 ./build/zephyr/zephyr.lst:56191:int32_t iis2dh_acceleration_raw_get(stmdev_ctx_t *ctx, int16_t *val)
11 ./build/zephyr/zephyr.lst:56231:int32_t iis2dh_device_id_get(stmdev_ctx_t *ctx, uint8_t *buff)
12 Binary file ./build/zephyr/CMakeFiles/zephyr.dir/home/ted/projects/zephyr-based/modules/hal/st/sensor/stmemsc/iis2dh_STdC/driver/iis2dh_reg.c.obj matches
13 Binary file ./build/zephyr/libzephyr.a matches
14 Binary file ./build/zephyr/drivers/sensor/iis2dh/CMakeFiles/drivers__sensor__iis2dh.dir/iis2dh_trigger.c.obj matches
15 Binary file ./build/zephyr/drivers/sensor/iis2dh/CMakeFiles/drivers__sensor__iis2dh.dir/iis2dh_i2c.c.obj matches
16 Binary file ./build/zephyr/drivers/sensor/iis2dh/CMakeFiles/drivers__sensor__iis2dh.dir/iis2dh.c.obj matches
17 Binary file ./build/zephyr/drivers/sensor/iis2dh/libdrivers__sensor__iis2dh.a matches
18 guest@vm:~/projects/zephyr-based/project-stage-1$

Looks like there are actually many more IIS2DH API routines available in the modules/hal source file from STMicro:

ted@localhost:~/projects/zephyr-based/z4-sandbox-kionix-work/modules/hal/st/sensor/stmemsc/iis2dh_STdC/driver$ grep -nr stmdev_ctx_t ./*.c
49:int32_t iis2dh_read_reg(stmdev_ctx_t* ctx, uint8_t reg, uint8_t* data,
67:int32_t iis2dh_write_reg(stmdev_ctx_t* ctx, uint8_t reg, uint8_t* data,
182:int32_t iis2dh_temp_status_reg_get(stmdev_ctx_t *ctx, uint8_t *buff)
196:int32_t iis2dh_temp_data_ready_get(stmdev_ctx_t *ctx, uint8_t *val)
215:int32_t iis2dh_temp_data_ovr_get(stmdev_ctx_t *ctx, uint8_t *val)
234:int32_t iis2dh_temperature_raw_get(stmdev_ctx_t *ctx, int16_t *val)
253:int32_t iis2dh_temperature_meas_set(stmdev_ctx_t *ctx, iis2dh_temp_en_t val)
275:int32_t iis2dh_temperature_meas_get(stmdev_ctx_t *ctx, iis2dh_temp_en_t *val)
304:int32_t iis2dh_operating_mode_set(stmdev_ctx_t *ctx, iis2dh_op_md_t val)
343:int32_t iis2dh_operating_mode_get(stmdev_ctx_t *ctx, iis2dh_op_md_t *val)
371:int32_t iis2dh_data_rate_set(stmdev_ctx_t *ctx, iis2dh_odr_t val)
392:int32_t iis2dh_data_rate_get(stmdev_ctx_t *ctx, iis2dh_odr_t *val)
445:int32_t iis2dh_high_pass_on_outputs_set(stmdev_ctx_t *ctx, uint8_t val)
467:int32_t iis2dh_high_pass_on_outputs_get(stmdev_ctx_t *ctx, uint8_t *val)
492:int32_t iis2dh_high_pass_bandwidth_set(stmdev_ctx_t *ctx, iis2dh_hpcf_t val)
519:int32_t iis2dh_high_pass_bandwidth_get(stmdev_ctx_t *ctx, iis2dh_hpcf_t *val)
553:int32_t iis2dh_high_pass_mode_set(stmdev_ctx_t *ctx, iis2dh_hpm_t val)
574:int32_t iis2dh_high_pass_mode_get(stmdev_ctx_t *ctx, iis2dh_hpm_t *val)
608:int32_t iis2dh_full_scale_set(stmdev_ctx_t *ctx, iis2dh_fs_t val)
629:int32_t iis2dh_full_scale_get(stmdev_ctx_t *ctx, iis2dh_fs_t *val)
663:int32_t iis2dh_block_data_update_set(stmdev_ctx_t *ctx, uint8_t val)
684:int32_t iis2dh_block_data_update_get(stmdev_ctx_t *ctx, uint8_t *val)
704:int32_t iis2dh_filter_reference_set(stmdev_ctx_t *ctx, uint8_t *buff)
720:int32_t iis2dh_filter_reference_get(stmdev_ctx_t *ctx, uint8_t *buff)
734:int32_t iis2dh_xl_data_ready_get(stmdev_ctx_t *ctx, uint8_t *val)
752:int32_t iis2dh_xl_data_ovr_get(stmdev_ctx_t *ctx, uint8_t *val)
770:int32_t iis2dh_acceleration_raw_get(stmdev_ctx_t *ctx, int16_t *val)
804:int32_t iis2dh_device_id_get(stmdev_ctx_t *ctx, uint8_t *buff)
818:int32_t iis2dh_self_test_set(stmdev_ctx_t *ctx, iis2dh_st_t val)
839:int32_t iis2dh_self_test_get(stmdev_ctx_t *ctx, iis2dh_st_t *val)
870:int32_t iis2dh_data_format_set(stmdev_ctx_t *ctx, iis2dh_ble_t val)
891:int32_t iis2dh_data_format_get(stmdev_ctx_t *ctx, iis2dh_ble_t *val)
919:int32_t iis2dh_boot_set(stmdev_ctx_t *ctx, uint8_t val)
940:int32_t iis2dh_boot_get(stmdev_ctx_t *ctx, uint8_t *val)
959:int32_t iis2dh_int_occurrencies_get(stmdev_ctx_t *ctx, uint8_t *val)
974:int32_t iis2dh_status_get(stmdev_ctx_t *ctx, iis2dh_status_reg_t *val)
1001:int32_t iis2dh_int1_gen_conf_set(stmdev_ctx_t *ctx, iis2dh_int1_cfg_t *val)
1016:int32_t iis2dh_int1_gen_conf_get(stmdev_ctx_t *ctx, iis2dh_int1_cfg_t *val)
1031:int32_t iis2dh_int1_gen_source_get(stmdev_ctx_t *ctx, iis2dh_int1_src_t *val)
1047:int32_t iis2dh_int1_gen_threshold_set(stmdev_ctx_t *ctx, uint8_t val)
1070:int32_t iis2dh_int1_gen_threshold_get(stmdev_ctx_t *ctx, uint8_t *val)
1090:int32_t iis2dh_int1_gen_duration_set(stmdev_ctx_t *ctx, uint8_t val)
1114:int32_t iis2dh_int1_gen_duration_get(stmdev_ctx_t *ctx, uint8_t *val)
1147:int32_t iis2dh_int2_gen_conf_set(stmdev_ctx_t *ctx, iis2dh_int2_cfg_t *val)
1162:int32_t iis2dh_int2_gen_conf_get(stmdev_ctx_t *ctx, iis2dh_int2_cfg_t *val)
1176:int32_t iis2dh_int2_gen_source_get(stmdev_ctx_t *ctx, iis2dh_int2_src_t *val)
1192:int32_t iis2dh_int2_gen_threshold_set(stmdev_ctx_t *ctx, uint8_t val)
1215:int32_t iis2dh_int2_gen_threshold_get(stmdev_ctx_t *ctx, uint8_t *val)
1235:int32_t iis2dh_int2_gen_duration_set(stmdev_ctx_t *ctx, uint8_t val)
1259:int32_t iis2dh_int2_gen_duration_get(stmdev_ctx_t *ctx, uint8_t *val)
1291:int32_t iis2dh_high_pass_int_conf_set(stmdev_ctx_t *ctx, iis2dh_hp_t val)
1312:int32_t iis2dh_high_pass_int_conf_get(stmdev_ctx_t *ctx, iis2dh_hp_t *val)
1358:int32_t iis2dh_pin_int1_config_set(stmdev_ctx_t *ctx, iis2dh_ctrl_reg3_t *val)
1373:int32_t iis2dh_pin_int1_config_get(stmdev_ctx_t *ctx, iis2dh_ctrl_reg3_t *val)
1389:int32_t iis2dh_int2_pin_detect_4d_set(stmdev_ctx_t *ctx, uint8_t val)
1411:int32_t iis2dh_int2_pin_detect_4d_get(stmdev_ctx_t *ctx, uint8_t *val)
1432:int32_t iis2dh_int2_pin_notification_mode_set(stmdev_ctx_t *ctx,
1456:int32_t iis2dh_int2_pin_notification_mode_get(stmdev_ctx_t *ctx,
1486:int32_t iis2dh_int1_pin_detect_4d_set(stmdev_ctx_t *ctx, uint8_t val)
1508:int32_t iis2dh_int1_pin_detect_4d_get(stmdev_ctx_t *ctx, uint8_t *val)
1528:int32_t iis2dh_int1_pin_notification_mode_set(stmdev_ctx_t *ctx,
1551:int32_t iis2dh_int1_pin_notification_mode_get(stmdev_ctx_t *ctx,
1580:int32_t iis2dh_pin_int2_config_set(stmdev_ctx_t *ctx, iis2dh_ctrl_reg6_t *val)
1595:int32_t iis2dh_pin_int2_config_get(stmdev_ctx_t *ctx, iis2dh_ctrl_reg6_t *val)
1622:int32_t iis2dh_fifo_set(stmdev_ctx_t *ctx, uint8_t val)
1643:int32_t iis2dh_fifo_get(stmdev_ctx_t *ctx, uint8_t *val)
1662:int32_t iis2dh_fifo_watermark_set(stmdev_ctx_t *ctx, uint8_t val)
1685:int32_t iis2dh_fifo_watermark_get(stmdev_ctx_t *ctx, uint8_t *val)
1705:int32_t iis2dh_fifo_trigger_event_set(stmdev_ctx_t *ctx, iis2dh_tr_t val)
1728:int32_t iis2dh_fifo_trigger_event_get(stmdev_ctx_t *ctx, iis2dh_tr_t *val)
1757:int32_t iis2dh_fifo_mode_set(stmdev_ctx_t *ctx, iis2dh_fm_t val)
1780:int32_t iis2dh_fifo_mode_get(stmdev_ctx_t *ctx, iis2dh_fm_t *val)
1815:int32_t iis2dh_fifo_status_get(stmdev_ctx_t *ctx, iis2dh_fifo_src_reg_t *val)
1829:int32_t iis2dh_fifo_data_level_get(stmdev_ctx_t *ctx, uint8_t *val)
1847:int32_t iis2dh_fifo_empty_flag_get(stmdev_ctx_t *ctx, uint8_t *val)
1865:int32_t iis2dh_fifo_ovr_flag_get(stmdev_ctx_t *ctx, uint8_t *val)
1883:int32_t iis2dh_fifo_fth_flag_get(stmdev_ctx_t *ctx, uint8_t *val)
1914:int32_t iis2dh_tap_conf_set(stmdev_ctx_t *ctx, iis2dh_click_cfg_t *val)
1929:int32_t iis2dh_tap_conf_get(stmdev_ctx_t *ctx, iis2dh_click_cfg_t *val)
1943:int32_t iis2dh_tap_source_get(stmdev_ctx_t *ctx, iis2dh_click_src_t *val)
1958:int32_t iis2dh_tap_threshold_set(stmdev_ctx_t *ctx, uint8_t val)
1980:int32_t iis2dh_tap_threshold_get(stmdev_ctx_t *ctx, uint8_t *val)
2001:int32_t iis2dh_shock_dur_set(stmdev_ctx_t *ctx, uint8_t val)
2024:int32_t iis2dh_shock_dur_get(stmdev_ctx_t *ctx, uint8_t *val)
2046:int32_t iis2dh_quiet_dur_set(stmdev_ctx_t *ctx, uint8_t val)
2071:int32_t iis2dh_quiet_dur_get(stmdev_ctx_t *ctx, uint8_t *val)
2093:int32_t iis2dh_double_tap_timeout_set(stmdev_ctx_t *ctx, uint8_t val)
2117:int32_t iis2dh_double_tap_timeout_get(stmdev_ctx_t *ctx, uint8_t *val)
2151:int32_t iis2dh_act_threshold_set(stmdev_ctx_t *ctx, uint8_t val)
2174:int32_t iis2dh_act_threshold_get(stmdev_ctx_t *ctx, uint8_t *val)
2194:int32_t iis2dh_act_timeout_set(stmdev_ctx_t *ctx, uint8_t val)
2216:int32_t iis2dh_act_timeout_get(stmdev_ctx_t *ctx, uint8_t *val)
2248:int32_t iis2dh_spi_mode_set(stmdev_ctx_t *ctx, iis2dh_sim_t val)
2269:int32_t iis2dh_spi_mode_get(stmdev_ctx_t *ctx, iis2dh_sim_t *val)

ted@localhost:~/projects/zephyr-based/z4-sandbox-kionix-work/modules/hal/st/sensor/stmemsc/iis2dh_STdC/driver$ 

^ Zephyr RTOS Tie-In To STMicro IIS2DH Driver API

File `$ENV{ZEPHYR_BASE}/drivers/sensor/iis2dh/iis2dh.c` end with:ii2

312 struct iis2dh_data iis2dh_data;
313
314 DEVICE_DT_INST_DEFINE(0, iis2dh_init, NULL,
315              &iis2dh_data, &iis2dh_cfg, POST_KERNEL,
316              CONFIG_SENSOR_INIT_PRIORITY, &iis2dh_driver_api);

...Somewhere data member `&iis2dh_data` gets assigned a value. This data member in turn is referenced when the above driver API routines are called. For example in routine `iis2dh_sample_fetch()` there is reference to an stmdev_ctx_t structure that's assigned to the device handle's "data" member:

203 static int iis2dh_sample_fetch(const struct device *dev,
204                                enum sensor_channel chan)
205 {
206         struct iis2dh_data *iis2dh = dev->data;
207         int16_t buf[3];
208
209         /* fetch raw data sample */
210         if (iis2dh_acceleration_raw_get(iis2dh->ctx, buf) < 0) {
211                 LOG_DBG("Failed to fetch raw data sample");
212                 return -EIO;
213         }
214
215         iis2dh->acc[0] = sys_le16_to_cpu(buf[0]);
216         iis2dh->acc[1] = sys_le16_to_cpu(buf[1]);
217         iis2dh->acc[2] = sys_le16_to_cpu(buf[2]);
218
219         return 0;
220 }

The structure `iis2dh_data` is defined in corresponding header file `iis2dh.h` as:

 59 /* sensor data */
 60 struct iis2dh_data {
 61         const struct device *bus;
 62         int16_t acc[3];
 63         uint32_t gain;
 64
 65         stmdev_ctx_t *ctx;
 66 #ifdef CONFIG_IIS2DH_TRIGGER
 67         const struct device *dev;
 68         const struct device *gpio;
 69         uint8_t gpio_pin;
 70         struct gpio_callback gpio_cb;
 71         sensor_trigger_handler_t drdy_handler;
 72 #if defined(CONFIG_IIS2DH_TRIGGER_OWN_THREAD)
 73         K_KERNEL_STACK_MEMBER(thread_stack, CONFIG_IIS2DH_THREAD_STACK_SIZE);
 74         struct k_thread thread;
 75         struct k_sem gpio_sem;
 76 #elif defined(CONFIG_IIS2DH_TRIGGER_GLOBAL_THREAD)
 77         struct k_work work;
 78 #endif /* CONFIG_IIS2DH_TRIGGER_GLOBAL_THREAD */
 79 #endif /* CONFIG_IIS2DH_TRIGGER */
 80 #if DT_INST_SPI_DEV_HAS_CS_GPIOS(0)
 81         struct spi_cs_control cs_ctrl;
 82 #endif
 83 };

Structure stmdev_ctx_t is defined:

110 typedef int32_t (*stmdev_write_ptr)(void *, uint8_t, uint8_t*, uint16_t);
111 typedef int32_t (*stmdev_read_ptr) (void *, uint8_t, uint8_t*, uint16_t);
112 
113 typedef struct {
114   /** Component mandatory fields **/
115   stmdev_write_ptr  write_reg;
116   stmdev_read_ptr   read_reg;
117   /** Customizable optional pointer **/
118   void *handle;
119 } stmdev_ctx_t;

^ Assignment To ctx Structure

So question, where is *ctx assigned a value? Ah, *ctx is assigned a value in the zephyr/drivers/sensor/iis2dh/iis2dh_i2c.c file. This value is a data structure which entails two C function pointers. Code excerpt here:

 19 #if DT_ANY_INST_ON_BUS_STATUS_OKAY(i2c)
 20
 21 static uint16_t iis2dh_i2c_slave_addr = DT_INST_REG_ADDR(0);
 22
 23 LOG_MODULE_DECLARE(IIS2DH, CONFIG_SENSOR_LOG_LEVEL);
 24
 25 static int iis2dh_i2c_read(struct iis2dh_data *data, uint8_t reg_addr,
 26                            uint8_t *value, uint16_t len)
 27 {
 28         return i2c_burst_read(data->bus, iis2dh_i2c_slave_addr,
 29                               reg_addr | 0x80, value, len);
 30 }
 31
 32 static int iis2dh_i2c_write(struct iis2dh_data *data, uint8_t reg_addr,
 33                             uint8_t *value, uint16_t len)
 34 {
 35         return i2c_burst_write(data->bus, iis2dh_i2c_slave_addr,
 36                                reg_addr | 0x80, value, len);
 37 }
 38
 39 stmdev_ctx_t iis2dh_i2c_ctx = {
 40         .read_reg = (stmdev_read_ptr) iis2dh_i2c_read,
 41         .write_reg = (stmdev_write_ptr) iis2dh_i2c_write,
 42 };
 43
 44 int iis2dh_i2c_init(const struct device *dev)
 45 {
 46         struct iis2dh_data *data = dev->data;
 47
 48         data->ctx = &iis2dh_i2c_ctx;
 49         data->ctx->handle = data;
 50
 51         return 0;
 52 }
 53 #endif /* DT_ANY_INST_ON_BUS_STATUS_OKAY(i2c) */

^ edit point

  dev->data->ctx->.read_reg = (stmdev_read_ptr) iis2dh_i2c_read
             ^^^
              :
  Valid when *data is typecast as `struct iis2dh_data`.

346 __syscall int i2c_transfer(const struct device *dev,
347                            struct i2c_msg *msgs, uint8_t num_msgs,
348                            uint16_t addr);
349 
350 static inline int z_impl_i2c_transfer(const struct device *dev,
351                                       struct i2c_msg *msgs, uint8_t num_msgs,
352                                       uint16_t addr)
353 {
354         const struct i2c_driver_api *api =
355                 (const struct i2c_driver_api *)dev->api;
356 
357         return api->transfer(dev, msgs, num_msgs, addr);
358 }

607 static inline int i2c_burst_read(const struct device *dev,
608                                  uint16_t dev_addr,
609                                  uint8_t start_addr,
610                                  uint8_t *buf,
611                                  uint32_t num_bytes)
612 {
613         return i2c_write_read(dev, dev_addr,
614                               &start_addr, sizeof(start_addr),
615                               buf, num_bytes);
616 }

572 static inline int i2c_write_read(const struct device *dev, uint16_t addr,
573                                  const void *write_buf, size_t num_write,
574                                  void *read_buf, size_t num_read)
575 {
576         struct i2c_msg msg[2];
577 
578         msg[0].buf = (uint8_t *)write_buf;
579         msg[0].len = num_write;
580         msg[0].flags = I2C_MSG_WRITE;
581 
582         msg[1].buf = (uint8_t *)read_buf;
583         msg[1].len = num_read;
584         msg[1].flags = I2C_MSG_RESTART | I2C_MSG_READ | I2C_MSG_STOP;
585 
586         return i2c_transfer(dev, msg, 2, addr);
587 }

346 __syscall int i2c_transfer(const struct device *dev,
347                            struct i2c_msg *msgs, uint8_t num_msgs,
348                            uint16_t addr);
349 
350 static inline int z_impl_i2c_transfer(const struct device *dev,
351                                       struct i2c_msg *msgs, uint8_t num_msgs,
352                                       uint16_t addr)
353 {
354         const struct i2c_driver_api *api =
355                 (const struct i2c_driver_api *)dev->api;
356 
357         return api->transfer(dev, msgs, num_msgs, addr);
358 }

^ Why Does iis2dh_device_id_get Return 3 When No Device Connected?

Following routine in STMicro's driver API code base returns ASCII "3", decimal 51 even when no device connected. This is the ID value spec'd in the IIS2DH datasheet. How is this value getting returned? The routine in question is here:

 796 /**
 797   * @brief  DeviceWhoamI .[get]
 798   *
 799   * @param  ctx      read / write interface definitions
 800   * @param  buff     buffer that stores data read
 801   * @retval          interface status (MANDATORY: return 0 -> no Error)
 802   *
 803   */
 804 int32_t iis2dh_device_id_get(stmdev_ctx_t *ctx, uint8_t *buff)
 805 {
 806   int32_t ret;
 807   ret = iis2dh_read_reg(ctx, IIS2DH_WHO_AM_I, buff, 1);
 808   return ret;
 809 }

From comment block it looks like the value 3 in our situation is an error value coming from routine `iis2dh_read_reg()`. This routine is defined:

  39 /**
  40   * @brief  Read generic device register
  41   *
  42   * @param  ctx   read / write interface definitions(ptr)
  43   * @param  reg   register to read
  44   * @param  data  pointer to buffer that store the data read(ptr)
  45   * @param  len   number of consecutive register to read
  46   * @retval          interface status (MANDATORY: return 0 -> no Error)
  47   *
  48   */
  49 int32_t iis2dh_read_reg(stmdev_ctx_t* ctx, uint8_t reg, uint8_t* data,
  50                         uint16_t len)
  51 {
  52   int32_t ret;
  53   ret = ctx->read_reg(ctx->handle, reg, data, len);
  54   return ret;
  55 }

Ok this begs the question then where and how are the ctx function pointers assigned to point to functions? We were working to answer this question yesterday, and it is something of a repeat of a key question we faced when building the out-of-tree driver for Kionix sensor . . .

^ Configuration Post from ST Micro Forum

Excerpt on accelerator configurations from this developer: mhackney (Community Member) Edited by ST Community July 21, 2018 at 5:26 PM Posted on January 02, 2017 at 16:21

Ok, I overlooked the data sheet that Low Power mode is 8-bit data output. But that still does not explain why the data is not left aligned?

Also, here is my complete configuration to sanity check:

// setup CTRL_REG1

accelerometer_write(CTRL_REG1, 0b10011100); // ODR 5.376kHz in LPMode [7-4] Low power enable [3] Z enable [2]

// setup CTRL_REG2

accelerometer_write(CTRL_REG2, 0b00110001); //

// setup CTRL_REG3

accelerometer_write(CTRL_REG3, 0b01000000); // AOI (And Or Interrupt) on INT1 en [6]

// setup CTRL_REG6

accelerometer_write(CTRL_REG6, 0b00000000); //

// setup CTRL_REG4

accelerometer_write(CTRL_REG4, 0b00110000); // Full-scale selection 16G [5-4]

// setup CTRL_REG5

accelerometer_write(CTRL_REG5, 0b01001010); // FIFO enable [6] Latch INT1 [3]

// setup INT1_CFG

accelerometer_write(INT1_CFG, 0b00100000); // ZHIE enabled [5]

// setup INT1_THS

accelerometer_write(INT1_THS, Z_PROBE_SENSITIVITY); // 40

// setup INT1_DURATION

accelerometer_write(INT1_DURATION, 0);

^ LIS2DH Data Structure

LIS2DH data structure, comparable to IIS2DH data structure but no `ctx` element:

220 struct lis2dh_data {
221         const struct device *bus;
222         const struct lis2dh_transfer_function *hw_tf;
223 
224         union lis2dh_sample sample;
225         /* current scaling factor, in micro m/s^2 / lsb */
226         uint32_t scale;
227 
228 #ifdef CONFIG_LIS2DH_TRIGGER
229         const struct device *dev;
230         const struct device *gpio_int1;
231         const struct device *gpio_int2;
232         struct gpio_callback gpio_int1_cb;
233         struct gpio_callback gpio_int2_cb;
234 
235         sensor_trigger_handler_t handler_drdy;
236         sensor_trigger_handler_t handler_anymotion;
237         atomic_t trig_flags;
238         enum sensor_channel chan_drdy;
239 
240 #if defined(CONFIG_LIS2DH_TRIGGER_OWN_THREAD)
241         K_KERNEL_STACK_MEMBER(thread_stack, CONFIG_LIS2DH_THREAD_STACK_SIZE);
242         struct k_thread thread;
243         struct k_sem gpio_sem;
244 #elif defined(CONFIG_LIS2DH_TRIGGER_GLOBAL_THREAD)
245         struct k_work work;
246 #endif
247 
248 #endif /* CONFIG_LIS2DH_TRIGGER */
249 
250 #if DT_ANY_INST_ON_BUS_STATUS_OKAY(spi)
251         struct spi_cs_control cs_ctrl;
252 #endif /* DT_ANY_INST_ON_BUS_STATUS_OKAY(spi) */
253 };

207 struct lis2dh_transfer_function {
208         int (*read_data)(const struct device *dev, uint8_t reg_addr,
209                          uint8_t *value, uint8_t len);
210         int (*write_data)(const struct device *dev, uint8_t reg_addr,
211                           uint8_t *value, uint8_t len);
212         int (*read_reg)(const struct device *dev, uint8_t reg_addr,
213                         uint8_t *value);
214         int (*write_reg)(const struct device *dev, uint8_t reg_addr,
215                          uint8_t value);
216         int (*update_reg)(const struct device *dev, uint8_t reg_addr,
217                           uint8_t mask, uint8_t value);
218 };

 68 int lis2ds12_i2c_init(const struct device *dev)
 69 {
 70         struct lis2ds12_data *data = dev->data;
 71 
 72         data->hw_tf = &lis2ds12_i2c_transfer_fn;
 73 
 74         return 0;
 75 }
 76 #endif /* DT_ANY_INST_ON_BUS_STATUS_OKAY(i2c) */

 60 static const struct lis2ds12_transfer_function lis2ds12_i2c_transfer_fn = {
 61         .read_data = lis2ds12_i2c_read_data,
 62         .write_data = lis2ds12_i2c_write_data,
 63         .read_reg  = lis2ds12_i2c_read_reg,
 64         .write_reg  = lis2ds12_i2c_write_reg,
 65         .update_reg = lis2ds12_i2c_update_reg,
 66 };
 67 

17 #include "lis2ds12.h"
 18 
 19 #if DT_ANY_INST_ON_BUS_STATUS_OKAY(i2c)
 20 
 21 static uint16_t lis2ds12_i2c_slave_addr = DT_INST_REG_ADDR(0);
 22 
 23 LOG_MODULE_DECLARE(LIS2DS12, CONFIG_SENSOR_LOG_LEVEL);
 24 
 25 static int lis2ds12_i2c_read_data(struct lis2ds12_data *data, uint8_t reg_addr,
 26                                  uint8_t *value, uint8_t len)
 27 {
 28         return i2c_burst_read(data->comm_master, lis2ds12_i2c_slave_addr,
 29                               reg_addr, value, len);
 30 }
 31 
 32 static int lis2ds12_i2c_write_data(struct lis2ds12_data *data, uint8_t reg_addr,
 33                                   uint8_t *value, uint8_t len)
 34 {
 35         return i2c_burst_write(data->comm_master, lis2ds12_i2c_slave_addr,
 36                                reg_addr, value, len);
 37 }

^ LIS2DH Sample Fetch Routine

What is going on in this LIS2DH API routine by STMicro, especially at line 107?

 81 static int lis2dh_sample_fetch(const struct device *dev,
 82                                enum sensor_channel chan)
 83 {
 84         struct lis2dh_data *lis2dh = dev->data;
 85         size_t i;
 86         int status;
 87 
 88         __ASSERT_NO_MSG(chan == SENSOR_CHAN_ALL ||
 89                         chan == SENSOR_CHAN_ACCEL_XYZ);
 90 
 91         /*
 92          * since status and all accel data register addresses are consecutive,
 93          * a burst read can be used to read all the samples
 94          */
 95         status = lis2dh->hw_tf->read_data(dev, LIS2DH_REG_STATUS,
 96                                           lis2dh->sample.raw,
 97                                           sizeof(lis2dh->sample.raw));
 98         if (status < 0) {
 99                 LOG_WRN("Could not read accel axis data");
100                 return status;
101         }
102 
103         for (i = 0; i < (3 * sizeof(int16_t)); i += sizeof(int16_t)) {
104                 int16_t *sample =
105                         (int16_t *)&lis2dh->sample.raw[1 + i];
106 
107                 *sample = sys_le16_to_cpu(*sample);
108         }
109 
110         if (lis2dh->sample.status & LIS2DH_STATUS_DRDY_MASK) {
111                 return 0;
112         }
113 
114         return -ENODATA;
115 }

^ LIS2DH Driver Output at Boot Time

Some output from Kionix driver demo, interesting early message, earlier even than Zephyr RTOS banner message:

[00:00:00.408,569] <inf> lis2dh: bus=I2C_1 fs=2, odr=0x4 lp_en=0x0 scale=9576
*** Booting Zephyr OS build v2.6.0-rc1-ncs1  ***
+++ Kionix Driver Demo version 0p2 +++
- SUCCESS - found Kionix accelerometer and device is ready
- DEV - starting comparative LIS2DH test thread . . .zzz -  - zzz
Success finding lis2dh device,
Call to device_is_ready() says LIS2DH sensor is ready,
Device name found to be 'LIS2DH'
lis2dh task at loop iteration 0x00000000
Failed to set odr: -134
Sampling at 1 Hz (asuuming so as sensor_attr_set returns 0 status - success
sampling at 1 Hz, per call to sensor_attr_get(),
#0 @ 1519 ms: x -0.306432 , y -0.383040 , z -9.614304
fetched and got acceleration readings 0, 4294660864

zzz -  - zzz
zzz -  - zzz
zzz -  - zzz
lis2dh task at loop iteration 0x00000001
Failed to set odr: -134
Sampling at 1 Hz (asuuming so as sensor_attr_set returns 0 status - success
sampling at 1 Hz, per call to sensor_attr_get(),
#1 @ 4525 ms: x -0.421344 , y -0.229824 , z -9.614304
fetched and got acceleration readings 0, 4294545952

zzz -  - zzz
zzz -  - zzz
zzz -  - zzz
lis2dh task at loop iteration 0x00000002
Failed to set odr: -134
Sampling at 1 Hz (asuuming so as sensor_attr_set returns 0 status - success
sampling at 1 Hz, per call to sensor_attr_get(),
#2 @ 7530 ms: x -0.268128 , y -0.268128 , z -9.576000
fetched and got acceleration readings 0, 4294699168

zzz -  - zzz
zzz -  - zzz
zzz -  - zzz
lis2dh task at loop iteration 0x00000003
Failed to set odr: -134
Sampling at 1 Hz (asuuming so as sensor_attr_set returns 0 status - success
sampling at 1 Hz, per call to sensor_attr_get(),
#3 @ 10536 ms: x -0.344736 , y -0.344736 , z -9.652608
fetched and got acceleration readings 0, 4294622560

zzz -  - zzz
   .
   .
   .

^ ENOTSUP Definition

</pre> ted@localhost:~/projects/zephyr-based/z4-sandbox-kionix-work/zephyr$ grep -nr ENOTSUP ./* | grep define | grep ENOTSUP ./drivers/flash/jesd216.h:326: * @retval -ENOTSUP if the erase type index is undefined. ./include/usb/bos.h:67:#define usb_handle_bos(x, y, z) -ENOTSUP ./lib/libc/minimal/include/errno.h:115:#define ENOTSUP 134 /**< Unsupported value */ ./subsys/net/ip/net_shell.c:3973:#define ping_ipv6(...) -ENOTSUP ./subsys/net/ip/net_shell.c:4082:#define ping_ipv4(...) -ENOTSUP ./subsys/usb/os_desc.h:34:#define usb_handle_os_desc(x, y, z) -ENOTSUP ./subsys/usb/os_desc.h:35:#define usb_handle_os_desc_feature(x, y, z) -ENOTSUP ./tests/kernel/fpu_sharing/float_disable/src/k_float_disable.c:39:#define K_FLOAT_DISABLE_SYSCALL_RETVAL -ENOTSUP

ted@localhost:~/projects/zephyr-based/z4-sandbox-kionix-work/zephyr$ </pre>

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