Nano 2GB camera bandwidth

Hello everyone,

I tried raspberry pi hq (imx477) camera with jetson Nano 2GB dev. board and I got 29-30fps (via argus_camera).

Nano have 2 lane csi at 1.5Gbps, so total bandwidth is 3Gbps.
camera bandwidth = 4032*3040 * 10bpp * 30fps = 3.42Gbps.
So camera bandwidth is higher that allowed jetson bandwidth and it’s working.

Explain me please, how is it possible? Where am I wrong?

hello prapor,

please check Sensor Software Driver Programming Guide, it’s Sensor Pixel Clock to calculate the exposure and frame rate of the sensor.
the sensor resolution is not the final output size. It is the total number of pixels the sensor used to generate the final output size.
assume you’d download this package to enable support for Raspberry Pi IMX477 for Jetson Nano 2GB.
you may disassembler the dtb binary into text file for checking pixel clock settings, it’s pix_clk_hz = "840000000"; in the configuration.
for example,
dtc -I dtb -O dts -o output.txt tegra210-p3448-0003-p3542-0000.dtb

after that,
you’ll need to check frame length and line length for getting this, you may looking into imx477_mode_tbls.h for default settings.
for example, it’s 0x342-0x343 for the line length, and 0x340-0x341 for the frame length.
the calculation formula is shown as…9024 * 3102 * 30 = 839,773,440.
hence, the configure of the sensor pixel clock as 840,000,000, in the device tree property.