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MSP-EXP430FR4133: MSP-EXP430FR4133

Part Number: MSP-EXP430FR4133
Other Parts Discussed in Thread: ADS7042, MSP430FR4133,


I am running an ADS7042 on the 430FR4133.

My goal is to sample the ADS7042 at around 600ksps. To do that I need to get the clock above 16MHz so I need to enable the enhanced clock. 

Can you provide some guidance on how to setup the enhanced clock mode?


  • Hi Malcolm,

    Can you refer me to where the enhanced clock mode is specified in the MSP430FR4133 data sheet? I only see 16MHz operation specified for this device.



  • Hi Leo,

    I see the reference to to enhanced clock mode in the: 

    "MSP430FR4xx and MSP430FR2xx family User's Guide"

    Table 3-10. CSCTL6 Register Description

    3-2 XT1HFFREQ RW 0h The XT1 high-frequency selection. These bits must be set to appropriate
    frequency for crystal or bypass modes of operation. (1)
    00b = 1 MHz to 4 MHz
    01b = Above 4 MHz to 6 MHz
    10b = Above 6 MHz to 16 MHz
    11b = Above 16 MHz to 24 MHz (available in enhanced clock system only)

    I see the reference to "available in enhanced clock mode" and I would like to understand how to (or if you can) set the clock greater than 16MHz.

    My objective is to get the MSP-EXP430FR4133  communicating with the SPI to sample the ADS7042 at 600-700 ksps. I can get the SPI clock to 1MHz, but appears that I need a higher SPI clock of 1MHz to achieve that 700 ksps.

    If you can shed any light on the enhanced clock, or a coding solution to achieve the 700 ksps that would be appreciated.



  • As far as I know, the Enhanced Clock System is only available on the FR2355 (and siblings). 

    You can run the SPI up to 8MHz [Ref data sheet (SLAS865B) Table 5-13]

    [Edit: I just noticed User Guide (SLAU445I) Table 3-1, which says this explicitly.]

  • Hi Bruce,

    Yes. I did see where the manuals reference the 8MHz clock. The problem that I am running into is that when I try to set the SPI clock above 1MHz, the SPI clock signal becomes distorted (the clock signals are no longer peak to peak and are not clean). So I was wondering if I needed to enable the Enhanced Clock System to produce a faster base clock to feed the SPI clock. Hence my questions was more about the Enhanced Clock Mode.

    So I agree that the manuals do say 8MHz SPI, but I can only get 1MHz.

    Any thoughts?



  • The Enhanced Clock System is something you have or you don't -- you don't need to switch it on.

    How bad are the signals (at 8MHz) actually? I've found most SPI slaves fairly forgiving. How does it look at 4MHz?

    To keep things in perspective, if you could run the SPI at 8MHz (non-stop), you would get 500ksps, which with a 16MHz MCLK gives you 32 CPU clocks, or something like 5-8 instructions, per sample. The FR4133 doesn't have DMA, so you'll need to feed the Tx side and then fetch the Rx bytes and make words out of them , which will easily take up 3/4ths of those instructions. I think you'll find you don't have any time left to do anything with the data. Once you estimate how much CPU your actual data processing will take, you might find that a 4MHz or even 1MHz SPI is adequate.

  • Hi Bruce.

    I was able to get the SPI running at 8MHz and close to 400k samples. I changed the SPI source clock.

    You are correct with your calculations. I knew it would be tight, but had a ADS7042 and wanted to see what I could achieve.

    Do you have any recommendations for dev kits that I might be able to use to achieve the 600ksps to 700ksps?



  • 1) The FR2355 sub-family can run at 24MHz, but SPI is still 8MHz and there's no DMA

    2) The F5529 sub-family can run at 25MHz, with SPI up to Fsystem (25MHz) and has DMA. Keeping the DMA/SPI running continuously is challenging.

    3) The MSP432P4 series can run at 48MHz, with SPI up to 24MHz, and has a fairly sophisticated DMA -- Ping-Pong can keep the DMA/SPI running continuously. It's a Cortex-M4, not an MSP430, but you'll find the peripherals (mostly) familiar.

  • Hi Bruce,

    Thanks you for you help.


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