AFE5809: I want to see demodulated data by proper SPI setting

Hi Junseong,

Thanks for reaching out and apologies for delayed response!

I went over your code and I found that while writing the data to the respective interface, you are not selecting the sub-chip.

Please refer to Table 2 (register address bit description) and Figure 85 in the datasheet which shows demodulator subchip 0 and subchip 1. It shows that the SPI register address is 8 bits and is made of 2 subchip select bits and 6 register address bits. SPI register data is 16 bits.

The SCID0_SEL enables configuration of channels 1 through 4. SCID1_SEL enables configuration of channels 5 through 8. When performing demodulator SPI write transactions, these SCID bits can be individually or mutually used with a specific register address.

Hence, for example, in your code you are writing 0x0041 in register 1F to set the decimation factor to 1, you should change the address to 0xDF (11011111) to select the sub-chips.

Similarly, 0x0A should be replace with 0xCA and so on.

Please make the necessary modifications and I hope it should work for you. Let me know if you any further questions.

Thanks & regards,

Abhishek

Hi Junseong,

Also, I am assuming while writing the SPI either in the demod or in the ADC/VCA, you are taking care of the DIG_SPI_EN pin. Furthermore, please take care of the EN_DEMOD registor in the VCA (0x16). 

Before making any changes to the demod registors you should make EN_DEMOD = 0 (taking care of DIG_SPI_EN) since the demodulator registers can be reset when 0x16[0] is set as 0. Thus, it is required to reconfigure the demodulator registers after toggling the 0x16[0] from 1 to 0.

Regards,
Abhishek