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Hi everyone,
I am following the VOXL Emulator documentation to set up my development environment for VOXL 2. However, I am unable to find the specific docker image file qrb5165-emulator_V1.5.tgz mentioned in the guide.
If the documentation is outdated, could someone provide the direct link or the current naming convention for the QRB5165 emulator image?
Thanks!
@Alex-Kushleyev Hi Alex,
Thank you for the clarification.
That makes sense regarding the accel parsing—agreed that a 4 LSB discrepancy on a 20-bit value is negligible compared to in-flight noise, but it’s good to see it will be corrected.
Appreciate you taking the time to investigate and confirm.
Igor
@Alex-Kushleyev Hi Alex,
Thank you for the clear and concise explanation.
@dvz I have faced a similar issue on the VOXL2 Mini. The X and Y axes match the documentation, but the Z axis has the opposite direction to what is described.
While auditing the IMU driver logic for the QRB5165 (icm42688.cpp), I identified two significant logical errors in how the ICM-42688-P FIFO data is retrieved and parsed. These bugs affect data integrity and 20-bit precision.
Bug 1: Incorrect FIFO_COUNT Latching Sequence (Race Condition)
Location: src/drivers/icm42688.c (inside read_imu_fifo)
The current implementation reads fifo_count starting from FIFO_COUNTH (0x2E).
// first read how many bytes are available using the fifo_count register
ret = voxl_spi_read_reg_word(bus, count_address, &fifo_count);
but acording to IMU document we must read FIFO_COUNTL to latch the data
Bug 2: Index Mismatch in 20-bit HiRes Packet Parsing
Location: fifo_read function under #ifdef HIRES_FIFO
Technical Detail:
When parsing Packet 4 (20-byte), the code maps the extension bits (lower 4 bits) incorrectly for the accelerometer.
ax32 = ((int32_t)ax16 << 4) | ((base[11] & 0xF0) >> 4);
ay32 = ((int32_t)ay16 << 4) | ((base[12] & 0xF0) >> 4);
az32 = ((int32_t)az16 << 4) | ((base[13] & 0xF0) >> 4);
It uses byte indices 11, 12, and 13, but these correspond to Gyro Z and Temperature data. The correct indices are 17, 18, and 19.
