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I/Q data on CC253x cont'd

Mario P.
Prodigy 60 points

Hello everyone,

we are currently developing an application with the CC253x and need access to the I/Q data on

output pins. We ask you for a little push in the right direction by answering a few of our questions.


From this thread we learned how to pass data of the RF ADC to particular output pins and did so for the 'rfc_rand_x' values:

e2e.ti.com/.../1325268

Here is what we already did:


    MCU_IO_DIR_OUTPUT(1, 4);
    MCU_IO_DIR_OUTPUT(1, 5);
    RFC_OBS_CTRL0 = 0x18;
    RFC_OBS_CTRL1 = 0x17;
    OBSSEL4 = OBSSEL_OBS_CTRL0;
    OBSSEL5 = OBSSEL_OBS_CTRL1;


However, we still got questions left:
 
- Which is the right value to set to the particular register to obtain I/Q instead of 'rfc_rand_q' and

'rfc_rand_i'? (This is the missing piece of information in the referenced thread)

- And a more generally understanding question: How are the I/Q values represented on the

output pins after finding the right combination? How are they represented in registers? (#bits?)

- In addition, is it possible to access the relevant registers  directly in software? Are the mentioned

'reserved' registers meant to do this? (e.g., access in the ti-mac firmware example trough

existing register access macros)

Thank you very much!

Regards
Mario

  • 0
    Prodigy 60 points
    Hello again,

    we dived a little further into the topic and found some points

    regarding the receiving path that would be helpful to get affirmed.

    - There are two ADC on the receiving path for I and Q

    - Both sample at 8 M samples per second

    - Both have 8 bit resolution


    In addition, we would like to precise some of our questions.

    - Is it possible to read out the internal registers saving these samples?

    - On the other hand, is it possible to route the signals going from the

    antenna to the ADCs to pins P1[0:5]? (Is this the actual debug mode spoken

    of in the other thread?)


    By now, we will start checking out all combinations for RFC_OBS_CTRLx

    and see if we are lucky finding the right one and deal with the ADC test modes.


    We would appreciate your help very much!

    Regards
    Mario