AWR1243: CSI Datarate

Antonio Puglielli

Part Number: AWR1243

I would like to understand the relationship between chirp parameters, and required datarate on the CSI interface.

The average data rate per frame is: (NUM_SAMPLES * NUM_BITS * 2 * NUM_RX * NUM_CHIRPS_PER_FRAME) / (FRAME_TIME)
The peak data rate per chirp is: (NUM_SAMPLES * NUM_BITS * 2 * NUM_RX) / (IDLE_TIME + RAMP_END_TIME)

An example chirp profile:

NUM_SAMPLES = 1024
NUM_BITS = 16
NUM_RX = 4

IDLE_TIME = 35us
RAMP_END_TIME = 65us

CHIRPS_PER_FRAME = 10
FRAME_TIME = 10ms

Based on these numbers, I calculate an average (per-frame) data rate of 131 Mbit/s and a peak (per-chirp) datarate of 1.31 Gbit/s.

My experimentation suggests that the CSI datarate needs to be set to accommodate the higher limit. For example, I observe that using a 1.2 Gbit/s CSI configuration does not return data, while using a 1.8 Gbit/s configuration does. Can you confirm this is the expected behavior?

Thanks for your assistance,
Antonio

over 6 years ago

0 Antonio Puglielli over 6 years ago

Expert 1025 points

To add onto this - the behavior that I see is that when the datarate is too low, some chirps are dropped.

Can you confirm that the CSI datarate should be set based on criterion (2) - peak datarate per chirp - instead of (1)?

0 Kaushal Kukkar over 6 years ago in reply to Antonio Puglielli

TI__Expert 7215 points

Antonio,

Data rate requirement on CSI2 is 1.31gbps, so for each lane it is 1.31/4mbps.

Device supports 150, 225, 300, 450, 600, 900 mbps data rate for each lane. To support above, you need to choose 450 mbps or higher.

Regards,
Kaushal

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AWR1243: CSI Datarate