Difference between revisions of "Iis2dh"
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Routine `int i2c_burst_read()` is a Zephyr in-tree driver routine. In possibly erroneous C syntax the assignment from the Zephyr device structure handle on down is: | Routine `int i2c_burst_read()` is a Zephyr in-tree driver routine. In possibly erroneous C syntax the assignment from the Zephyr device structure handle on down is: | ||
Revision as of 23:10, 15 October 2021
Contents
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) */
|
Routine `int i2c_burst_read()` is a Zephyr in-tree driver routine. In possibly erroneous C syntax the assignment from the Zephyr device structure handle on down is: dev->data->ctx->.read_reg = (stmdev_read_ptr) iis2dh_i2c_read
^^^
|
Valid when *data is typecast as `struct iis2dh_data`. Routine `iis2dh_i2c_read` calls `i2c_burst_read`, which in turn calls ``. |
Excerpt from zephyr/include/drivers/i2c.h:
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 }
</i>
|}
<!-- comment -->
== [[#top|^]] 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:
<pre>
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 ForumExcerpt 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
// setup CTRL_REG2
// setup CTRL_REG3
// setup CTRL_REG6
// setup CTRL_REG4
// setup CTRL_REG5
// setup INT1_CFG
// setup INT1_THS
// setup INT1_DURATION
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