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Original question:

EMB1428Q: EMB1428 SPI Issue

EMB1428Q: EMB1428 CEXT1 CEXT2 no waveform output

Troy.Tsai
Intellectual 365 points
Part Number: EMB1428Q

Hi,

We've done testing our own board. The SPI is working fine. But we still cannot measure 1MHz square waveform between CEXT1 and CEXT2.

SPI can return what command I just send. Fault code is 0b000. We only connect SDI, SDO, CLK, CS, RESET to our MCU.

DIR, DIR_RT, EN, DONE are all floating. 

Issue:

Does the internal 1MHz clock work after power-on? 12V and 5V is all set. Or I need to setup any GPIO for finish EMB1428 internal clock  initialization?

BR,

Troy

  • 0
    TI__Mastermind 19795 points

    Hi Troy,

    Thank you for your question!

    Just to confirm, are you measuring the CEXT1/2 differential signal from the pins or after other components?

    Also, could you pull nCS low, and measure SCLK from the device to see if the clock is correctly reaching that portion of the circuit?

    The internal 1MHz clock should work after power-on of the device, but the external clock signals (CEXT1/2) are meant to simply provide voltage ripple for the charge pump. Therefore the easier way to measure/ensure operation of the 1MHz clock would be to pull nCS low and measure SCLK.

    Regards,

    Vince

  • 0 in reply to Vince
    Intellectual 365 points

    Hi Vince,

    Thank you for your response!

    Yes,I'm measuring CEXT1/CEXT2 differential signal.

    I connect CS to GND, and measure SCLK. The SCLK onis alway on 3.4V. No waveform output. 

    I only connect 12V and 5V. 5V is driven by 7805.

    PWR pin I connect:

    VDDP:12V

    VDD12V:12V

    VDD5V: 5V

    VDDIO: 5V

    BR,

    Troy

  • 0 in reply to Troy.Tsai
    TI__Mastermind 19795 points

    Hi Troy,

    One additional check to see if the signal is working:

    Please try doing standard SPI communications from the microcontroller to the device, and monitor the SCLK communications. If the device is communicating properly, then you should see SCLK turning on and off with each communication packet.

    If you do not see any clock during either the response or the command request, then please let me know. This will help diagnose where the clock signal configuration issue is coming from (microcontroller or EMB).

    Ideally, if you are able to correctly receive any data, then that would assume that the clock is working correctly on both sides.

    Thanks,

    Vince

  • 0 in reply to Vince
    Intellectual 365 points

    Hi Vince,

    Yes. SPI looks fine.

    I only connect SDI, SDO, SCLK, CS, RESET to MCU. Other GPIO is floating now. e.g. DIR, DIR_RT, EN, DONE...

    EMB1428 can return what command I send. But no fault code.

    The he charge pump output voltage is same to VSTACK. This is why I want to know if internal clock is working! Thanks!

    BR,

    Troy

  • 0 in reply to Troy.Tsai
    TI__Mastermind 19795 points

    Hi Troy,

    This is surprising that there is no fault code being returned, but commands can be received. 

    First, are you looking for the fault code on the EMB1428Q's SDO pin?

    Next:

    Do you mean that (1) the fault code you are receiving is all zeroes? Or do you mean (2) you are receiving no bytes at all where the fault code should be (completely missing bytes the 4 fault bytes on SDO)?

    1. If the former, then this is correct, the device will return all zeroes for the fault code if there are no issues.
    2. If the latter, then this is a communication issue likely sourced from an incorrect transaction (you will need to step through the microcontroller code using a debugger and see if the command frame is being sent properly).

    Unfortunately, we are unable to assist directly with this device software (the software for this device and that of the EM1402/EMB1499 will be "not recommended for new designs" very soon), so other than high-level support, I cannot dig into the issue too much further. I apologize for this inconvenience.

    Regards,

    Vince Toledo