Part Number:IWR1642BOOST
Hi,
I'm trying to use a modified configuration with the Traffic Monitoring demo code (v2.0 from the mmWave Industrial Toolbox v2.3), but can't get it to work with the desired parameter values.
I used the mmWave Sensing Estimator to generate configuration parameters, based on the long range default values and the following updated inputs:
- Maximum detectable range = 140 m
- Range resolution = 200 cm
- Maximum velocity = 180 km/h
- Velocity resolution = 1 km/h
The calculated configuration outputs then include:
- Frequency slope = 5.99 MHz/us
- Sampling rate = 6208 ksps
- # samples per chirp = 78
- # chirp loops = 356
- Idle time = 2 us
- ADC valid start time = 4.20 us
- Ramp end time = 17.76 us
And all seems good: "no errors are found".
I then modified the default mmw_tm_demo_longRange.cfg file to update the profileCfg and frameCfg lines as follows:
- profileCfg 0 76 2.0 4.2 17.76 0 0 5.99 1 78 6208 0 0 48
- frameCfg 0 0 356 0 50 1 0
The configuration loads without reporting any errors, but I get no data messages back. The original configuration works fine with frame results messages at 20 Hz as expected.
By trial and error, it seems there are two problems:
- The ramp end time must be greater than approximately 27 us.
- The number of chirp loops must be less than 128.
If I modify the profileCfg and frameCfg lines again so both of these are satisfied, I get data as expected. If the ramp end time is less than 27 us, or the number of chirps per frame is greater than 127, it doesn't work. I've tried e.g. increasing the idle time to balance the reduction in ramp time, but that has no effect.
I can't see anything in the SDK user guide or source code that explains this - please can you help?