111 lines
4.5 KiB
Markdown
111 lines
4.5 KiB
Markdown
# STEVAL-MKI217V1 polling test (Genesys2)
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This standalone bare-metal application reads the LSM6DSOX on the
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STEVAL-MKI217V1 over the existing Genesys2 PMOD SPI peripheral. It does not
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use INT1/INT2. The LIS2MDL magnetometer on the module is not enabled in this
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first electrical/readout smoke test; it is internally reachable through the
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LSM6DSOX sensor hub and will be integrated separately after the IMU link is
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verified.
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## Wiring
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| STEVAL-MKI217V1 | Genesys2 | Function |
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| CS | JC1 | active-low chip select |
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| SDA | JC2 | SPI MOSI / SDI |
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| SDO | JC3 | SPI MISO |
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| SCL | JC4 | SPI clock / SPC |
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| VDD | 3.3 V | sensor supply |
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| VDDIO | 3.3 V | digital I/O supply |
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| GND | GND | common ground |
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`CS` is mandatory for four-wire SPI. Never feed 5 V to VDDIO. JC9 is the
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optional sensor interrupt pin but is deliberately unused here.
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## Hardware bring-up results (2026-07-13)
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The Genesys2/Rocket ELF was loaded over GDB and the UART output was captured
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on `/dev/ttyUSB0`. All eight identity reads returned `0xff` instead of the
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expected `0x6c`. In that trial SCL, SDA, SDO, VDDIO, VDD and GND were connected
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but CS was not. An all-`0xff` response is therefore the expected open/unselected
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SPI-bus result, not a valid sensor sample.
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After CS was connected to JC1, all eight identity reads returned `0x6c` and
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configuration read-back returned `CTRL1_XL=0x40`, `CTRL2_G=0x40`,
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`CTRL3_C=0x44` and `STATUS=0x07`.
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The original FPGA SPI implementation sampled MISO on the data-change edge.
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A first 60-second diagnostic log consequently contained about 68.4% bit-shifted
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samples. The generic SPI control register was extended with independent CPOL
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and CPHA bits while retaining the single/quad-width bit. Mode 0 is selected by
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this driver and has been verified on hardware. A Mode-3 probe returned an
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incorrect identity byte (`0x28`), so the CPHA=1 path is not yet production
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validated.
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One additional LSM6DSOX-specific issue was found: a 14-byte burst crossing the
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`OUT_TEMP_H` to `OUTX_L_G` internal output-block boundary shifted the remaining
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stream by one bit. Delaying between bytes did not help. The permanent readout
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therefore uses a 2-byte temperature burst followed by one coherent 12-byte
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gyro+accelerometer burst. This is not sample filtering or post-processing; it
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matches the sensor's output block structure and preserves BDU coherence.
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The final real-hardware capture is
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`../fusion/logs/steval_mki217v1_clean_60s.csv`:
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- 6349 samples over 59.994462 seconds (105.810 Hz measured)
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- sequence discontinuities: 0
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- bit-shifted, saturated or invalid samples: 0
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- maximum timestamp gap: 4742 CLINT ticks (9.484 ms)
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- acceleration norm: 9.94245 +/- 0.00687 m/s^2
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- gyro mean XYZ: +0.20395, -0.07578, -0.27628 deg/s
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- gyro standard deviation XYZ: 0.02600, 0.02379, 0.02630 deg/s
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- temperature: 25.909 +/- 0.056 degC
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These measurements are for the stationary board in its test orientation. The
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nonzero gyro mean is startup bias to be estimated by stationary calibration,
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not angular motion.
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## Build and load
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From the repository root:
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```sh
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make FPGA_BOARD=genesys2 fpga-elf-flash-image \
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APP=steval_mki217v1_test
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make FPGA_BOARD=genesys2 fpga-debug-load \
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APP=steval_mki217v1_test
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```
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The default run is 104 Hz for 60 seconds. Alternatives can be passed through
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the application directory build:
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```sh
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make -C soc/software/steval_mki217v1_test \
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BUILD_DIR=../../out/software/steval_mki217v1_test \
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LSM6DSOX_ODR_HZ=52 CAPTURE_DURATION_S=60
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```
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Supported smoke-test ODR values are 52, 104 and 208 Hz. At 115200 baud, use
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52 or 104 Hz for loss-free line-oriented logging. The firmware verifies
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`WHO_AM_I=0x6c`, selects SPI mode 0, resets the device, enables
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block-data-update and register auto-increment, and configures +/-2 g and
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+/-250 dps. The FPGA SPI controller exposes CPOL/CPHA independently from its
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single/quad data-width selection.
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## UART/replay format
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Each sample is timestamped from the local CLINT/CPU time domain before its SPI
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burst and emitted without floating-point formatting:
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```text
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IMU_META,LSM6DSOX,tick_hz=500000,odr_hz=104,accel_ug_lsb=61,gyro_udps_lsb=8750,temp_lsb_c=256,temp_offset_millic=25000
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IMU_RAW,LSM6DSOX,0,12345678,ax,ay,az,gx,gy,gz,temp
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```
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Scale factors are 61 ug/LSB, 8750 udps/LSB and 256 LSB/degC with a 25 degC
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offset. `fusion/fusion_eskf.py` accepts this raw format directly, so a captured
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log can be replayed with an existing GPS UART capture. Sequential GPS and IMU
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captures are meaningful only for a stationary test. A moving-platform replay
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requires GPS and IMU samples stamped in the same firmware/run.
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