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CDCEL913: How to config the the CDCEL913 correctly?

Intellectual 660 points

Replies: 2

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Part Number: CDCEL913

Hi,

    I am now trying to configuring the CDCEL913 to output the specified clock frequency on the Y1, Y2, and Y3 output.

    By checking the data sheet, the chip will output 27MHz frequency on Y1 ~ Y3 by default if the input clock source is 27MHz after the S0 input is set to 1. I do measure the 27MHz output on the scope after setting S0 to 1. However, none of the clock output on Y2 and Y3 if I write back the register values read from CDCEL913.

    Following are my test procedures by running a small application on the device.

1. Set S0 to 1.

2. Read back the registers(register address, value) through the I2C bus using byte mode(bit7=1 | reg address).

    {0x02, 0xB4},
    {0x03, 0x01},
    {0x04, 0x02},
    {0x05, 0x48},
    {0x06, 0x60},
    {0x10, 0x00},
    {0x11, 0x00},
    {0x12, 0x00},
    {0x13, 0x00},
    {0x14, 0x45},
    {0x15, 0x02},
    {0x16, 0x00},
    {0x17, 0x00},
    {0x18, 0xAF},
    {0x19, 0x50},
    {0x1A, 0x02},
    {0x1B, 0xC9},
    {0x1C, 0x00},
    {0x1D, 0x40},
    {0x1E, 0x02},
    {0x1F, 0x08}

3. Write back these registers with the same values listed above and measure the Y2/Y3 output.

    Is there anything wrong of my testing procedures? Should I set S0 to 1 after the write register operation? Or there is any special rules for the write register operation?

    Thanks.

      Todd

  • Hello,

    I reviewed your configuration and loaded it into ClockPro.

    It appears that you have set the PDiv2 = 0 (reset) and PDiv3 = 0 (reset) and are selecting that PDiv2/3 output for the Y2/Y3 output.

    I loaded the default config, you can see they also did a full bypasses around the PLL for 27 MHz output on all Y1/Y2/Y3.

    I recommend using ClockPro to make the configuration file and then program that config into the device.  Here is the default programming (according to the software Tools --> Go Default menu selection:

    Bit  ==>  76543210
    Byte 00 - 10000001
    Byte 01 - 00000001
    Byte 02 - 10110100
    Byte 03 - 00000001
    Byte 04 - 00000010
    Byte 05 - 01010000
    Byte 06 - 01000000
    Byte 07 - 00000000
    Byte 08 - 00000000
    Byte 09 - 00000000
    Byte 10 - 00000000
    Byte 11 - 00000000
    Byte 12 - 00000000
    Byte 13 - 00000000
    Byte 14 - 00000000
    Byte 15 - 00000000
    Byte 16 - 00000000
    Byte 17 - 00000000
    Byte 18 - 00000000
    Byte 19 - 00000000
    Byte 20 - 11101101
    Byte 21 - 00000010
    Byte 22 - 00000001
    Byte 23 - 00000001
    Byte 24 - 00000000
    Byte 25 - 01000000
    Byte 26 - 00000010
    Byte 27 - 00001000
    Byte 28 - 00000000
    Byte 29 - 01000000
    Byte 30 - 00000010
    Byte 31 - 00001000

    73,
    Timothy

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  • In reply to Timothy T:

    Hi Timothy,

    Thank for your information.

    I had downloaded the ClockPro tool and dump the register value of the default setting. I will apply these register value to see if the Y1/Y2/Y3 outputs are correct.

    Thanks.

    Todd

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