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drivers: sensors: bmi160: Fix issue with sample read

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When testing the bmi160 I've come across an issue where the readings
didn't make sense to me. The issue comes from reading the
BMI160_SAMPLE_BURST_READ_ADDR which is 0x0C assuming both accelerometer
and gyroscope. At this point we would normally read 12 bytes
(2 bytes per sample * 3 axes * 2 sensors). This reading takes place in
bmi160_sample_fetch and begins writing to data->sample.raw

Without this change, the first byte written is actually to the dummy
byte which effectively gets tossed. The issue is that this is the
GYR_X<7:0>(LSB) according to the BMI160 data sheet. When we later call
either bmi160_gyr_channel_get or bmi160_acc_channel_get we're looking
at sample.gyr and sample.acc (which is effectively shiften by 1 byte).

This change gets rid of the dummy byte which re-alignes gyr with the
start of the raw buffer.

Signed-off-by: Yuval Peress <peress@chromium.org>
This commit is contained in:
Yuval Peress 2020-11-17 00:08:57 -07:00 committed by Anas Nashif
parent 01da5ab1fc
commit beaf0230ba
2 changed files with 19 additions and 11 deletions
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1
drivers/sensor/bmi160/bmi160.h
View file

@ -468,7 +468,6 @@ union bmi160_pmu_status {
union bmi160_sample {
uint8_t raw[BMI160_BUF_SIZE];
struct {
uint8_t dummy_byte;
#if !defined(CONFIG_BMI160_GYRO_PMU_SUSPEND)
uint16_t gyr[BMI160_AXES];
#endif

29
subsys/emul/emul_bmi160.c
View file

@ -60,18 +60,21 @@ static const char *const pmu_name[] = {"acc", "gyr", "mag", "INV"};
static void sample_read(struct bmi160_emul_data *data, union bmi160_sample *buf)
{
int i;
/*
* Use hard-coded scales to get values just above 0, 1, 2 and
* 3, 4, 5. Values are stored in little endianess.
* gyr[x] = 0x0b01 // 3 * 1000000 / BMI160_GYR_SCALE(2000) + 1
* gyr[y] = 0x0eac // 4 * 1000000 / BMI160_GYR_SCALE(2000) + 1
* gyr[z] = 0x1257 // 5 * 1000000 / BMI160_GYR_SCALE(2000) + 1
* acc[x] = 0x0001 // 0 * 1000000 / BMI160_ACC_SCALE(2) + 1
* acc[y] = 0x0689 // 1 * 1000000 / BMI160_ACC_SCALE(2) + 1
* acc[z] = 0x0d11 // 2 * 1000000 / BMI160_ACC_SCALE(2) + 1
*/
static uint8_t raw_data[] = { 0x01, 0x0b, 0xac, 0x0e, 0x57, 0x12, 0x01, 0x00,
0x89, 0x06, 0x11, 0x0d };
LOG_INF("Sample read");
buf->dummy_byte = 0;
for (i = 0; i < BMI160_AXES; i++) {
/*
* Use hard-coded scales to get values just above 0, 1, 2 and
* 3, 4, 5.
*/
buf->acc[i] = sys_cpu_to_le16(i * 1000000 / 598 + 1);
buf->gyr[i] = sys_cpu_to_le16((i + 3) * 1000000 / 1065 + 1);
}
memcpy(buf->raw, raw_data, ARRAY_SIZE(raw_data));
}
static void reg_write(const struct bmi160_emul_cfg *cfg, int regn, int val)
@ -161,6 +164,12 @@ static int reg_read(const struct bmi160_emul_cfg *cfg, int regn)
case BMI160_SPI_START:
LOG_INF(" * Bus start");
break;
case BMI160_REG_ACC_RANGE:
LOG_INF(" * acc range");
break;
case BMI160_REG_GYR_RANGE:
LOG_INF(" * gyr range");
break;
default:
LOG_INF("Unknown read %x", regn);
}