[libbladeRF] RXVGA2 DC autocalibration intermittently returns 31 for all values

[jynik]

I'm seeing this occur on some boards, but not others. (However, I only have a very small sample size).

Currently, I'm digging into this and looking to query the Lime folks on their Google group for more info.

[jynik]

While terribly inconvenient, one workaround is to rerun cal dc lms until it stops returning 31's. This generally seems to yield some usable values, but may intermittently cause the LMS to go out to lunch.

I've been swamped with a few other tasks, but will be getting back to this soon.

[jynik]

I've verified this to be a timing issue in the FPGA by comparing transactions on the SPI bus to what the NIOS sees. @bpadalino is hot on the trail.

A temporary workaround is to slow down the LMS SPI bus clock rate. 5 MHz was rock solid for me.

[jynik]

Addressed by FPGA v0.1.1 (9c0bbfe)