Some questions on nRF52811 documentation

[Dmitry]

I'm studying nRF52811 manual, there are moments not clear to me:

1. Is I/Q sampling paused during SWITCHING slots? For example, if I configure 16 1-msec slots (8 switching + 8 sampling) with 125us sampling period, I'll get 64 or 128 samples?
2. TSAMPLEOFFSET is described as "Signed value offset before starting sampling in number of 16M cycles relative to the beginning of the REFERENCE state - 12 us after switching start". I'm completely lost... maybe you could describe this in other words to help me understand?
3. Can I use energy detection feature just for energy detection for custom 1-MBit protocol, not 802.15.4?
4. There is a note in radio electrical specification: "Typical sensitivity applies when ADDR0 is used for receiver address correlation. When ADDR[1...7] are used for receiver address correlation, the typical sensitivity for this mode is degraded by 3 dB". Is this because 1..7 are correlated sequentially? if so, can I be sure that sensitivity won't drop when I fill addresses 1..7 with the same value (I need only two addresses)?

Thanks

[Dmitry]

 Finally got a nRF52811, IQ sampling is awesome ) Still have no transmitter with antenna switch, so now playing with TX pattern.

My DFE configuration:

NRF_RADIO->DFEMODE = 2;
NRF_RADIO->DFECTRL1 = (16 << 0) | (0 << 7) | (2 << 8) | (6 << 12) | (0 << 15) | (6 << 16) | (0 << 24);
NRF_RADIO->DFECTRL2 = (0 << 0) | (0 << 16);

Here what I got with pattern F0 F0 FF F0 FF FF FF FF 00 FF ...

And again questions:

1) Range of I/Q values is about -150..+150, isn't it too low for 12-bit ADC? I use 10056 devkit as transmitter at 2 cm distance, TX power is 0 dbm, ADC backoff gain is 0.

2) I see there is 1-usec skip after 64 samples of reference period (8 usec). After that, a wave is continuous, so receiver does sampling even in switching slots? ok, it's very good for our case, just would like to be sure that it won't change in the next chip revision )

3) Still can't get TSAMPLEOFFSET. I figured out that changing it affects start of reference period (not start of sampling after it), and 0 corresponds something about 16 usec after ADDRESS event. Maybe it worth to update a documentation to make this item more clear?

Thanks!

[Armin_B]

Hi Dmitry

how did get a nrf52811 board to test? and which library you used to configure the DFE and I/Q sampling?

Thanks

[Dmitry]

Hi,

we're developing our own board, and our firmware is ran on bare metal 52811, without SD and libraries (own protocol, not BLE-compatible)

[Armin_B]

thank you for fast response. 

good luck

[Armin_B]

did you ever try to test CTE feature (continuous tone extension) at transmit?