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AFE031: I have several questions.

SeongMin PARK
Prodigy 30 points
Part Number: AFE031

hello. We are developing using AFE031.

1. What is the BPS of SPI communication? In which document can I find this information? The comments in the example code are confusing.
I would like to see the SPI protocol documentation.

2. Is it necessary to use DMA in DAC mode?

3. Is FSK out-spec if I don't use HRPWM?

  • 0
    TI__Guru 54111 points

    Hi SeongMin,

    SeongMin PARK said:
    1. What is the BPS of SPI communication?

    I think BPS refers to bps, typically is written in lower case, which means bit per second. It is the digital communication data rate unit. bps indicates how fast bits are transmitted in a second. It is determined by the  #_of_bit_transfered*SPI_clock_frequency (bits/second). SPI's clock frequency may be from kHz to several MHz, so this is how fast the data is being transferred in SPI protocol. 

    I replied to a different customer on the SPI topics yesterday. Below is the link of the reply. 

    https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/1313931/afe031-there-is-no-output-using-afe031

    SeongMin PARK said:
    2. Is it necessary to use DMA in DAC mode?

    This is the question for C2000 DSP processor team. I do not know what DSP processor you selected. If the selected DSP has fast clock routine, and able to handle the DAC instructions quickly, then the use of DMA may be not optional. Using DMA in DAC mode is a common practice in microcontroller; it is more efficient to transfer digital data to a DAC without involving the DSP's CPU for each data transfer. 

    I am not DSP firmware engineer and unable to address the specific question. I think that it depends on a DSP processor. FSK is a slow PLC protocol, so it is likely that you may handle the DAC transfer directly using CPU resources. 

    SeongMin PARK said:
    3. Is FSK out-spec if I don't use HRPWM?

    HRPWM stands for High-Resolution Pulse Width Modulation. I recalled that it is used in DSP that allows for a finer control of pulse width modulation signals compared to traditional PWM implementations. 

    I think that you can use regular PWM signals. Please keep in mind, all PWM signals in FSK input side has to be filtered out (use LPFs) to smooth out and generate a specific frequency that is equivalent to digital "0" and digital "1".  The mark frequency represents the binary "1" and space frequency represents the binary "0". It won't be an issue if the DSP/MCU is able to generate PWM signals and reproduce the specific sinusoidal waveform after the LPFs. 

    We have many customers that using AFE031 with ARM instead of DSP processor. So these changes are not the issues for AFE031, which is the PLC controller in hardware. You may do whatever, if your CMU/DSP is capable in encoding and decoding the Tx/Rx signals over the PLC network.

    If you have other questions, please let us know. 

    Best,

    Raymond