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RM48L952: RM48L952 interfacing parallel ADC concepts

Lorenz Gruebler
Prodigy 10 points
Part Number: RM48L952
Other Parts Discussed in Thread: ADS8588S

Dear Forum,

I ‘am developing a signal application with medium computational demand and possible safety relevance. Therefore I need measure several signal simultaneously.

As MCU I am planning to use a Hercules MCU, as ADC I want to attach a high speed parallel interface ADC (propably an ads8588s).

The maximum sample frequency of the channels will not go beyond 100 kHz, but each sampling will result in 8 channel (à 8 Words to transfer).

Because of the signals nature the will slightly wobble by a few percent (probably N2HET will be used to produce the CONVSTA, CONVSTB Signals). The Sampling is ongoing continuously in time.

Each end of conversion will be signalled by the BUSY Signal. From control theory perspective burst of several sampling could be transferred to RAM before they need to be evaluated, so DMA group transfer is possible.

Q: What is the most efficient way to transfer the result to a Hercules MCUs RAM?

Q: could the DMA be used? Does it make sense?

Q: is there any other way to connect a Hercules MCU to a high speed ADC?

Regards,

Lorenz

  • 0
    TI__Guru**** 186196 points

    Hi Lorenz,

    1. You can use DMA to transfer data between EMIF sync or asyc memory to MCU RAM

    2. Yes, 

    3. Does ADC support SPI interface? The MibSPI and SPI of RM48 supports up to 25MBPS.

  • 0 in reply to QJ Wang
    Prodigy 10 points

    Hello QJWang,

    Thank you for your reply,

    I’am walking through the RM48 and the ADC Manual, it seems that a finished ADC cycle of 8 Conversion is indicated by a falling edge of the BUSY Signal (see Diagram “Read After Conversion”). So at the moment I do not understand how to generate a DMA_REQ Signal based on the falling edge of BUSY Signal? Is there a way to drive the DMA by an external Interrupt, because BUSY cannot be connected to the EMIF directly (or may I’am wrong?).

    Q: Can the BUSY signal start a DMA_REQ?

    Q: At which Block should the BUSY signal be connected?

    Regards,

    Lorenz

  • +1 in reply to Lorenz Gruebler
    TI__Guru**** 186196 points

    There is no DMA request from EMIF. I don't know to interface MCU EMIF to ADS8588 ADC. You can start DMA transfer in GIO interrupt routine.

    If you use SPI to read ADC conversion result, when a character (2~16-bit, programmable) is being received, the SPI will signal the DMA via the DMA request signals. The DMA controller will then perform the required data transfer.